Pacific Operations Manual

![](media/image1.jpeg){width="4.0in" height="2.6465277777777776in"}

Version 2.0

15 August 2003

Intentionally left blank.

Table of Contents

[1 Introduction 1-7](#introduction)

[1.1 Arrangement of the POM 1-7](#arrangement-of-the-pom)

[1.2 Document Management 1-7](#document-management)

[1.3 Copies 1-8](#copies)

[1.4 Changes to the POM 1-8](#changes-to-the-pom)

[1.5 Editing conventions 1-8](#editing-conventions)

[1.6 Request For Change form 1-9](#request-for-change-form)

[1.7 Amendment Record 1-10](#amendment-record)

[2 Acronym List 2-1](#acronym-list)

[3 System Integrity and Monitoring
3-1](#system-integrity-and-monitoring)

[3.1 Introduction 3-1](#introduction-1)

[3.2 Personnel Licensing and Training
3-1](#personnel-licensing-and-training)

[3.3 Reference Documents 3-1](#reference-documents)

[3.4 System Performance Criteria 3-2](#system-performance-criteria)

[3.5 ATC System Validation 3-3](#atc-system-validation)

[3.5.1 System safety assessment 3-3](#system-safety-assessment)

[3.5.2 Integration test 3-3](#integration-test)

[3.5.3 ATS operation manuals 3-3](#ats-operation-manuals)

[3.5.4 ATS SYSTEM INTEGRITY 3-3](#ats-system-integrity)

[3.6 System Monitoring 3-3](#system-monitoring)

[3.6.1 The monitoring process 3-4](#the-monitoring-process)

[3.6.2 Dispatch of confidential information
3-4](#dispatch-of-confidential-information)

[3.6.3 FANS-1/A problem reports 3-4](#fans-1a-problem-reports)

[3.6.4 FANS-1/A periodic status report
3-5](#fans-1a-periodic-status-report)

[3.6.5 Processing of reports 3-5](#processing-of-reports)

[3.7 FANS Interoperability Team 3-5](#fans-interoperability-team)

[3.8 Central Reporting Agency 3-6](#central-reporting-agency)

[3.9 Local Data Recording and Analysis
3-6](#local-data-recording-and-analysis)

[3.9.1 Data recording 3-6](#data-recording)

[3.9.2 Local data collection 3-7](#local-data-collection)

[3.10 FANS-1/A Problem Report 3-8](#fans-1a-problem-report)

[3.10.1 Description of fields 3-9](#description-of-fields)

[3.11 FANS-1/A Periodic Status Report Form
3-10](#fans-1a-periodic-status-report-form)

[4 Connection Management 4-1](#connection-management)

[4.1 Pre-Flight Phase 4-1](#pre-flight-phase)

[4.1.1 Identifying data link aircraft
4-1](#identifying-data-link-aircraft)

[4.1.2 Registration number 4-1](#registration-number)

[4.2 The CPDLC Connection Sequence 4-2](#the-cpdlc-connection-sequence)

[4.3 The AFN Logon 4-2](#the-afn-logon)

[4.3.1 Prerequisite for CPDLC and / or ADS connection
4-2](#prerequisite-for-cpdlc-and-or-ads-connection)

[4.3.2 Initiating an AFN logon 4-2](#initiating-an-afn-logon)

[4.3.3 Purpose of an AFN logon 4-2](#purpose-of-an-afn-logon)

[4.3.4 The initial AFN logon 4-3](#the-initial-afn-logon)

[4.3.4.1 Parameter time for performing the initial AFN logon
4-3](#parameter-time-for-performing-the-initial-afn-logon)

[4.3.4.2 Notification of ATS variations
4-3](#notification-of-ats-variations)

[4.3.4.3 Constructing the FN_CON message
4-3](#constructing-the-fn_con-message)

[4.3.4.4 FMS and ACARS flight identification
4-3](#fms-and-acars-flight-identification)

[4.4 CPDLC Connection 4-3](#cpdlc-connection)

[4.4.1 Purpose CPDLC connection 4-3](#purpose-cpdlc-connection)

[4.4.2 Management Of CPDLC connections
4-4](#management-of-cpdlc-connections)

[4.4.3 CPDLC connection sequence 4-4](#cpdlc-connection-sequence)

[4.4.4 Active and inactive CPDLC connections
4-4](#active-and-inactive-cpdlc-connections)

[4.4.4.1 Determination of an active CPDLC connection
4-4](#__RefHeading___Toc49000507)

[4.5 Next Data Authority Notification
4-5](#next-data-authority-notification)

[4.5.1 Purpose of the NDA message 4-5](#purpose-of-the-nda-message)

[4.5.2 Procedure for the NDA notification
4-5](#procedure-for-the-nda-notification)

[4.5.2.1 Sequence of the NDA and FN_CAD messages
4-5](#sequence-of-the-nda-and-fn_cad-messages)

[4.5.2.2 Change of the NDA 4-5](#change-of-the-nda)

[4.5.3 Abnormal cases relating to the NDA notification
4-6](#abnormal-cases-relating-to-the-nda-notification)

[4.5.3.1 Unsuccessful NDA delivery 4-6](#unsuccessful-nda-delivery)

[4.5.3.2 Duplication of the NDA message
4-6](#duplication-of-the-nda-message)

[4.6 AFN Logon Triggered By Address Forwarding
4-6](#afn-logon-triggered-by-address-forwarding)

[4.6.1 Purpose and procedure 4-6](#purpose-and-procedure)

[4.6.2 An aircraft transferring from one data link area to another
4-6](#an-aircraft-transferring-from-one-data-link-area-to-another)

[4.6.3 Aircraft transiting data link areas
4-7](#aircraft-transiting-data-link-areas)

[4.6.3.1 Options for initiating the AFN logon
4-7](#options-for-initiating-the-afn-logon)

[4.6.3.2 Transferring CPDLC for short transits
4-8](#transferring-cpdlc-for-short-transits)

[4.7 End of Service and CPDLC Connection Transfer
4-8](#end-of-service-and-cpdlc-connection-transfer)

[4.7.1 Purpose and procedure 4-8](#purpose-and-procedure-1)

[[4.7.1.1]{.smallcaps} Uplink messages to be closed before the [End
Service]{.smallcaps}
4-8](#uplink-messages-to-be-closed-before-the-end-service)

[4.7.1.2 Use of Contact/Monitor Uplink Message
4-8](#use-of-contactmonitor-uplink-message)

[4.7.1.3 Synchronizing the CPDLC and voice transfer
4-9](#synchronizing-the-cpdlc-and-voice-transfer)

[4.7.1.4 Timing of the transfer of communications
4-9](#timing-of-the-transfer-of-communications)

[4.7.1.5 Aircraft entering VHF coverage
4-9](#aircraft-entering-vhf-coverage)

[4.7.1.6 Timing of the CPDLC connection
4-9](#timing-of-the-cpdlc-connection)

[4.7.2 Abnormal cases at the time of the connection / disconnection
4-10](#abnormal-cases-at-the-time-of-the-connection-disconnection)

[4.7.2.1 Non-delivery of [End Service]{.smallcaps} message
4-10](#non-delivery-of-end-service-message)

[4.7.2.2 Non-automatic termination of the connection
4-10](#non-automatic-termination-of-the-connection)

[5 CPDLC Procedures 5-1](#cpdlc-procedures)

[5.1 Means of Communication 5-1](#means-of-communication)

[5.1.1 General 5-1](#general)

[5.1.2 Voice communications 5-1](#voice-communications)

[5.1.2.1 Notification of frequencies to the preceding ATSU
5-1](#notification-of-frequencies-to-the-preceding-atsu)

[5.1.2.2 Notification of HF frequencies by CPDLC
5-1](#notification-of-hf-frequencies-by-cpdlc)

[5.2 CPDLC Capability 5-1](#cpdlc-capability)

[5.2.1 Notification of CPDLC capability
5-1](#notification-of-cpdlc-capability)

[5.2.2 Downlink messages 5-1](#downlink-messages)

[5.2.3 Uplink messages 5-2](#uplink-messages)

[5.3 Use of Pre-Formatted and Free Text Messages
5-2](#use-of-pre-formatted-and-free-text-messages)

[5.3.1 Preferred use of pre-formatted messages
5-2](#preferred-use-of-pre-formatted-messages)

[5.3.2 Standardized free text messages
5-2](#standardized-free-text-messages)

[5.3.3 Storing free text messages 5-2](#storing-free-text-messages)

[5.4 Exchange of CPDLC messages 5-2](#exchange-of-cpdlc-messages)

[5.4.1 Message assurance 5-2](#message-assurance)

[5.4.2 Ambiguous dialogues 5-2](#ambiguous-dialogues)

[5.4.3 Interruption of a CPDLC dialogue
5-2](#interruption-of-a-cpdlc-dialogue)

[5.4.4 Approval of request or clearance / instruction
5-3](#approval-of-request-or-clearance-instruction)

[5.4.4.1 Affirmative response to a clearance/instruction
5-3](#affirmative-response-to-a-clearanceinstruction)

[5.4.4.2 Affirmative response to a clearance request
5-3](#affirmative-response-to-a-clearance-request)

[5.4.4.3 Conditions relating to a specific clearance
5-3](#conditions-relating-to-a-specific-clearance)

[5.4.4.4 Affirmative response to a negotiation request
5-3](#affirmative-response-to-a-negotiation-request)

[5.4.5 Negative response to a downlink request
5-3](#negative-response-to-a-downlink-request)

[5.4.5.1 Negative response to a clearance request
5-3](#negative-response-to-a-clearance-request)

[5.4.5.2 Re-statement of a clearance 5-3](#re-statement-of-a-clearance)

[5.4.5.3 Explanation of negative response
5-3](#explanation-of-negative-response)

[5.4.5.4 Offering alternative clearances to downlink requests
5-3](#offering-alternative-clearances-to-downlink-requests)

[5.4.6 Negative response to an uplink request
5-3](#negative-response-to-an-uplink-request)

[5.4.7 Time period between receiving and responding to a message
5-4](#time-period-between-receiving-and-responding-to-a-message)

[5.4.7.1 Delays in responding 5-4](#delays-in-responding)

[5.4.7.2 Delay expected after receiving a "STANDBY" message
5-4](#delay-expected-after-receiving-a-standby-message)

[5.4.8 Re-sending Messages 5-4](#re-sending-messages)

[5.4.8.1 Re-sending of a message when no alert received
5-4](#re-sending-of-a-message-when-no-alert-received)

[5.4.8.2 Re-sending of a message when an alert has been received
5-4](#re-sending-of-a-message-when-an-alert-has-been-received)

[5.4.9 Duplicate requests received 5-4](#duplicate-requests-received)

[5.4.9.1 Second identical request after an uplink "STANDBY" message
5-4](#second-identical-request-after-an-uplink-standby-message)

[5.4.9.2 Multiple identical requests 5-4](#multiple-identical-requests)

[5.4.10 Altitude change clearances 5-4](#altitude-change-clearances)

[5.4.10.1 Issuing conditional altitude change clearances
5-4](#issuing-conditional-altitude-change-clearances)

[5.4.10.2 Level report requirements for climb or descent clearances
5-5](#level-report-requirements-for-climb-or-descent-clearances)

[5.4.10.3 Canceling block altitude clearances
5-5](#canceling-block-altitude-clearances)

[5.4.11 Requesting an aircraft's speed
5-5](#requesting-an-aircrafts-speed)

[5.4.12 Advising a wake turbulence offset
5-5](#advising-a-wake-turbulence-offset)

[5.4.13 Direct Tracking and UPR Aircraft
5-5](#direct-tracking-and-upr-aircraft)

[5.5 Multi-Element Requests 5-6](#multi-element-requests)

[5.5.1 Avoiding multiple element clearance requests
5-6](#avoiding-multiple-element-clearance-requests)

[5.5.2 Responding to multiple element clearance requests
5-6](#responding-to-multiple-element-clearance-requests)

[5.5.2.1 Multiple clearance requests in one message: All approved
5-6](#multiple-clearance-requests-in-one-message-all-approved)

[5.5.2.2 Multiple clearance requests in one message: All not approved
5-6](#multiple-clearance-requests-in-one-message-all-not-approved)

[5.5.2.3 Multiple clearance requests in one message: Some approved /
Some not approved
5-6](#multiple-clearance-requests-in-one-message-some-approved-some-not-approved)

[5.6 Multi-element Uplink Messages 5-7](#multi-element-uplink-messages)

[5.6.1 Combining multiple elements into a single message
5-7](#combining-multiple-elements-into-a-single-message)

[5.6.2 Dependent Clearances 5-7](#dependent-clearances)

[5.7 Message Closure 5-7](#message-closure)

[5.7.1 General 5-7](#general-1)

[5.7.2 Answering an uplink free text
5-8](#answering-an-uplink-free-text)

[5.7.3 Dialogue commenced via CPDLC and continued via voice
5-8](#dialogue-commenced-via-cpdlc-and-continued-via-voice)

[5.8 Position Reporting 5-8](#position-reporting)

[5.8.1 General 5-8](#general-2)

[5.8.2 Downlink of position report 5-8](#downlink-of-position-report)

[5.8.3 Flexible track position reports
5-8](#flexible-track-position-reports)

[5.8.4 First position report 5-8](#first-position-report)

[5.8.5 Sending of ATC waypoints only
5-8](#sending-of-atc-waypoints-only)

[5.8.6 Updating a waypoint estimate 5-8](#updating-a-waypoint-estimate)

[5.8.7 Non-receipt of a scheduled position report
5-9](#non-receipt-of-a-scheduled-position-report)

[5.8.8 Sequencing 'ABEAM' waypoints in excess of FMC parameters
5-9](#sequencing-abeam-waypoints-in-excess-of-fmc-parameters)

[5.8.9 ARINC 424 fix names 5-9](#arinc-424-fix-names)

[5.9 FANS-1/A CPDLC Message Set and Intent
5-9](#fans-1a-cpdlc-message-set-and-intent)

[5.9.1 Response Requirements Key: 5-9](#response-requirements-key)

[5.9.2 Uplink - Responses and Acknowledgements
5-9](#uplink---responses-and-acknowledgements)

[5.9.3 Uplink - Vertical Clearances 5-10](#uplink---vertical-clearances)

[5.9.4 Uplink - Crossing Constraints
5-12](#uplink---crossing-constraints)

[5.9.5 Uplink - Lateral Offsets 5-14](#uplink---lateral-offsets)

[5.9.6 Uplink - Route Modifications 5-15](#uplink---route-modifications)

[5.9.7 Uplink - Speed Changes 5-16](#uplink---speed-changes)

[5.9.8 Uplink - Contact/Monitor/Surveillance Requests
5-17](#uplink---contactmonitorsurveillance-requests)

[5.9.9 Uplink - Report/Confirmation Requests
5-17](#uplink---reportconfirmation-requests)

[5.9.10 Uplink - Negotiation Requests
5-18](#uplink---negotiation-requests)

[5.9.11 Uplink - Air Traffic Advisories
5-19](#uplink---air-traffic-advisories)

[5.9.12 Uplink - System Management Messages
5-19](#uplink---system-management-messages)

[5.9.13 Uplink - Additional Messages
5-19](#uplink---additional-messages)

[5.9.14 Downlink - Responses 5-20](#downlink---responses)

[5.9.15 Downlink - Vertical Requests
5-20](#downlink---vertical-requests)

[5.9.16 Downlink - Lateral Off-Set Requests
5-21](#downlink---lateral-off-set-requests)

[5.9.17 Downlink - Speed Requests 5-21](#downlink---speed-requests)

[5.9.18 Downlink - Voice Contact Requests
5-21](#downlink---voice-contact-requests)

[5.9.19 Downlink - Route Modification Requests
5-21](#downlink---route-modification-requests)

[5.9.20 Downlink - Reports 5-22](#downlink---reports)

[5.9.21 Downlink - Negotiation Requests
5-23](#downlink---negotiation-requests)

[5.9.22 Downlink - Emergency Messages
5-23](#downlink---emergency-messages)

[5.9.23 Downlink -System Management Messages
5-23](#downlink--system-management-messages)

[5.9.24 Downlink -Additional Messages
5-24](#downlink--additional-messages)

[5.10 FANS-1/A CPDLC Standard Free Text Messages
5-24](#fans-1a-cpdlc-standard-free-text-messages)

[5.10.1 Uplink - Free Text Report/ Confirmation Requests
5-25](#uplink---free-text-report-confirmation-requests)

[5.10.2 Uplink - Free Text Instructions
5-26](#uplink---free-text-instructions)

[5.10.3 Uplink - Freetext Advisories
5-26](#uplink---freetext-advisories)

[5.10.4 Uplink - Free Text Speed Messages
5-27](#uplink---free-text-speed-messages)

[5.10.5 Uplink - Free Text Emergency Acknowledgment
5-27](#uplink---free-text-emergency-acknowledgment)

[5.10.6 Downlink - Free Text Advisories
5-28](#downlink---free-text-advisories)

[6 ADS Procedures 6-1](#ads-procedures)

[6.1 Introduction 6-1](#introduction-2)

[6.2 ADS Description 6-1](#ads-description)

[6.2.1 The periodic contract 6-1](#the-periodic-contract)

[6.2.2 The event contract 6-1](#the-event-contract)

[6.2.3 The demand contract 6-2](#the-demand-contract)

[6.2.4 Emergency mode 6-2](#emergency-mode)

[6.3 Factors To Be Considered When Using ADS
6-2](#factors-to-be-considered-when-using-ads)

[6.3.1 Vertical and lateral variations
6-2](#vertical-and-lateral-variations)

[6.3.2 Figure of Merit (FOM) data in ADS reports
6-2](#figure-of-merit-fom-data-in-ads-reports)

[6.3.3 Flight crew modification of active route
6-3](#flight-crew-modification-of-active-route)

[6.4 ADS Connection Management 6-3](#ads-connection-management)

[6.4.1 Priority for the ADS connection
6-3](#priority-for-the-ads-connection)

[6.4.1.1 Allocation of ADS connections
6-3](#allocation-of-ads-connections)

[6.4.2 Near boundary ADS connections
6-3](#near-boundary-ads-connections)

[6.4.2.1 Monitoring of an aircraft operating close to an airspace
boundary
6-3](#monitoring-of-an-aircraft-operating-close-to-an-airspace-boundary)

[6.4.2.2 Other ground facilities requesting ADS contracts
6-4](#other-ground-facilities-requesting-ads-contracts)

[6.4.3 ADS connections not available
6-4](#ads-connections-not-available)

[6.4.4 Ground system termination of ADS connections
6-5](#ground-system-termination-of-ads-connections)

[6.5 Reporting Rates 6-5](#reporting-rates)

[6.5.1 General 6-5](#general-3)

[6.5.2 Appropriate reporting rates 6-5](#appropriate-reporting-rates)

[6.5.3 Avoid high periodic reporting rates
6-5](#avoid-high-periodic-reporting-rates)

[6.5.4 Other factors to be considered
6-5](#other-factors-to-be-considered)

[6.5.5 Default periodic reporting rates
6-5](#default-periodic-reporting-rates)

[6.6 Separation 6-5](#separation)

[6.6.1 Appropriate ADS reporting requirements
6-6](#appropriate-ads-reporting-requirements)

[6.6.2 Appropriate separation standard
6-6](#appropriate-separation-standard)

[6.6.3 Vertical separation 6-6](#vertical-separation)

[6.6.3.1 Vertical tolerance consistency
6-6](#vertical-tolerance-consistency)

[6.6.3.2 Application of vertical tolerances
6-6](#application-of-vertical-tolerances)

[6.6.3.3 ADS level information does not satisfy vertical tolerance
6-6](#ads-level-information-does-not-satisfy-vertical-tolerance)

[6.6.3.4 Use of ADS level information
6-6](#use-of-ads-level-information)

[6.6.3.5 Passing or leaving a level 6-6](#passing-or-leaving-a-level)

[6.6.4 Longitudinal separation 6-6](#longitudinal-separation)

[6.6.4.1 Limitations on the use of tools
6-6](#limitations-on-the-use-of-tools)

[6.6.4.2 Establishing longitudinal separation
6-6](#establishing-longitudinal-separation)

[6.6.4.3 Using extrapolated or interpolated positions
6-7](#using-extrapolated-or-interpolated-positions)

[6.6.4.4 Validity of displayed information
6-7](#validity-of-displayed-information)

[6.6.4.5 Time-based separation 6-7](#time-based-separation)

[6.6.4.6 .Distance-based separation 6-7](#distance-based-separation)

[6.6.5 Lateral separation 6-7](#lateral-separation)

[6.6.5.1 Areas of lateral conflict 6-7](#areas-of-lateral-conflict)

[6.7 Air Traffic Clearance Monitoring
6-7](#air-traffic-clearance-monitoring)

[6.7.1 Deviations from ATC clearances
6-7](#deviations-from-atc-clearances)

[6.8 Coordination 6-7](#coordination)

[6.8.1 Duty of care responsibility 6-7](#duty-of-care-responsibility)

[6.8.2 Coordinated data inconsistent with ADS displayed data
6-8](#coordinated-data-inconsistent-with-ads-displayed-data)

[6.9 Alerting service 6-8](#alerting-service)

[6.9.1 Late or missing ADS Reports 6-8](#late-or-missing-ads-reports)

[6.10 Aircraft Navigation 6-8](#aircraft-navigation)

[6.10.1 Aircraft in heading select mode
6-8](#aircraft-in-heading-select-mode)

[6.10.2 Sequencing subsequent waypoints
6-8](#sequencing-subsequent-waypoints)

[6.11 Position Reporting 6-8](#position-reporting-1)

[6.11.1 Position reporting requirements in ADS airspace
6-8](#position-reporting-requirements-in-ads-airspace)

[6.11.1.1 Publishing reporting requirements
6-8](#publishing-reporting-requirements)

[6.11.1.2 CPDLC report at FIR entry position
6-8](#cpdlc-report-at-fir-entry-position)

[6.11.1.3 Updating waypoint estimates 6-9](#updating-waypoint-estimates)

[6.11.1.4 Non-compulsory waypoints 6-9](#non-compulsory-waypoints)

[6.11.2 Discrepancies between ADS and CPDLC estimates
6-9](#discrepancies-between-ads-and-cpdlc-estimates)

[6.11.2.1 Actions to be followed when there is an estimate discrepancy
6-9](#actions-to-be-followed-when-there-is-an-estimate-discrepancy)

[7 Emergency and Non-routine Procedures
7-1](#emergency-and-non-routine-procedures)

[7.1 Emergency procedures 7-1](#emergency-procedures)

[7.1.1 Response to an emergency message
7-1](#response-to-an-emergency-message)

[7.1.2 Confirmation of emergency activation
7-1](#confirmation-of-emergency-activation)

[7.1.3 Acknowledgement of an emergency message
7-1](#acknowledgement-of-an-emergency-message)

[7.1.4 CPDLC acknowledgment 7-1](#cpdlc-acknowledgment)

[7.1.4.1 Voice contact 7-1](#voice-contact)

[7.1.5 Retaining the active connection
7-1](#retaining-the-active-connection)

[7.1.5.1 Communications responsibility
7-2](#communications-responsibility)

[7.1.5.2 Executive control responsibility
7-2](#executive-control-responsibility)

[7.1.6 Normal emergency procedures 7-2](#normal-emergency-procedures)

[7.1.7 Coordination in the case of emergency
7-2](#coordination-in-the-case-of-emergency)

[7.2 Data Link Connection Failures 7-2](#data-link-connection-failures)

[7.2.1 Detected by the controller 7-2](#detected-by-the-controller)

[7.2.2 Detected by the airborne system
7-2](#detected-by-the-airborne-system)

[7.2.3 Inability to establish the data link connection
7-2](#inability-to-establish-the-data-link-connection)

[7.3 Data link System Shutdowns 7-2](#data-link-system-shutdowns)

[7.3.1 Unexpected data link shutdowns
7-2](#unexpected-data-link-shutdowns)

[7.3.2 Planned data link shutdowns 7-3](#planned-data-link-shutdowns)

[7.3.3 Resumption of data link operations
7-3](#resumption-of-data-link-operations)

[7.3.4 Data link component shutdown 7-3](#data-link-component-shutdown)

[7.3.4.1 ADS only failure 7-3](#ads-only-failure)

[7.3.5 Unexpected communication service provider shutdown
7-3](#unexpected-communication-service-provider-shutdown)

[7.3.6 Unexpected avionics system shutdown
7-4](#unexpected-avionics-system-shutdown)

[7.4 Total Communications Failure 7-4](#total-communications-failure)

[7.5 Using CPDLC to relay messages 7-4](#using-cpdlc-to-relay-messages)

[8 FANS-1/A Implementation 8-1](#fans-1a-implementation)

[8.1 Introduction 8-1](#introduction-3)

[8.2 ATSU Designators 8-1](#atsu-designators)

[8.2.1 ICAO 8-1](#icao)

[8.2.2 ACARS ADDRESSES 8-1](#acars-addresses)

[8.3 HF Voice Communications Requirements
8-1](#hf-voice-communications-requirements)

[8.3.1 Pre-Departure 8-1](#pre-departure)

[8.3.2 Crossing International FIR Boundaries
8-1](#crossing-international-fir-boundaries)

[8.3.3 CPDLC Services Within The Tokyo FIR
8-2](#cpdlc-services-within-the-tokyo-fir)

[8.3.4 Logon Procedures within the Tokyo FIR
8-2](#logon-procedures-within-the-tokyo-fir)

[8.4 Differences of Use of FANS-1/A Messages
8-2](#differences-of-use-of-fans-1a-messages)

[8.5 Position Reporting Requirements: CPDLC and ADS Environments
8-3](#position-reporting-requirements-cpdlc-and-ads-environments)

[8.6 Aircraft Data 8-3](#aircraft-data)

[8.6.1 Verifying registration number
8-3](#verifying-registration-number)

[8.6.2 CPDLC connection requests 8-4](#cpdlc-connection-requests)

[8.6.3 Flight crew display:- response and acknowledgment
8-4](#flight-crew-display--response-and-acknowledgment)

[8.6.4 FMS processing of waypoints 8-5](#fms-processing-of-waypoints)

[8.6.5 Multiple request messages 8-5](#multiple-request-messages)

[8.6.6 Waypoint sequencing 8-6](#waypoint-sequencing)

[8.6.7 Network acknowledgement timer
8-6](#network-acknowledgement-timer)

[8.6.8 Open uplinks at time of transfer of communications
8-6](#open-uplinks-at-time-of-transfer-of-communications)

[8.6.9 Offset using the FMS 8-7](#offset-using-the-fms)

[8.6.10 Duplicate uplink messages 8-7](#duplicate-uplink-messages)

[8.7 FANS Interoperability Team Members
8-8](#fans-interoperability-team-members)

[8.8 Central Reporting Agency Members
8-8](#central-reporting-agency-members)

[8.8.1 North and Central Pacific (IPACG)
8-8](#north-and-central-pacific-ipacg)

[8.8.2 South Pacific (ISPACG) 8-9](#south-pacific-ispacg)

[9 Continental CPDLC Implementation
9-1](#continental-cpdlc-implementation)

[9.1 Introduction 9-1](#introduction-4)

[9.2 Concepts 9-1](#concepts)

[9.2.1 Supplement to Voice 9-1](#supplement-to-voice)

[9.2.2 Reduced Message Set 9-1](#reduced-message-set)

[9.2.3 Airspace 9-1](#airspace)

[9.3 Communications Media 9-1](#communications-media)

[9.3.1 Continental 9-1](#continental)

[[9.3.2]{.smallcaps} Use of CPDLC in Continental Airspace
9-1](#use-of-cpdlc-in-continental-airspace)

[9.3.3 Strategic CPDLC Application 9-1](#strategic-cpdlc-application)

[9.3.4 Tactical Voice 9-2](#tactical-voice)

[9.3.5 Voice Precedence 9-2](#voice-precedence)

[9.3.6 Imposing Voice Communications
9-2](#imposing-voice-communications)

[9.3.7 Change from Strategic to Tactical Situation
9-2](#change-from-strategic-to-tactical-situation)

[9.3.8 Message Compliance and Responses
9-2](#message-compliance-and-responses)

[9.3.9 Climb/Descent Phase 9-2](#climbdescent-phase)

[9.3.10 Crossing CPDLC System Boundaries
9-2](#crossing-cpdlc-system-boundaries)

[9.3.11 Jurisdiction Over Aircraft 9-2](#jurisdiction-over-aircraft)

[9.3.12 Dialogues During CPDLC Transfer
9-2](#dialogues-during-cpdlc-transfer)

[9.4 Message Set 9-2](#message-set)

[9.4.1 Recommended Uplink Message Set
9-3](#recommended-uplink-message-set)

[9.4.2 Recommended Downlink Message Set
9-4](#recommended-downlink-message-set)

[10 Index 10-1](#index)

[11 Endnotes 11-1](#endnotes)

# Introduction

The Pacific Operations Manual (POM) details the FANS-1/A procedures and
requirements applicable in the following Pacific FIRs:

-   Anchorage Oceanic

-   Auckland Oceanic

-   Brisbane

-   Nadi

-   Oakland

-   Tahiti

-   Tokyo (Oceanic Control Airspace only)

## Arrangement of the POM

The POM consists of the following Parts:

  ---------- ------------------------------------------------------------
  Section 1  Introduction and Document Management

  Section 2  Acronyms

  Section 3  System Integrity and Monitoring

  Section 4  Connection Management

  Section 5  Controller Pilot Data Link Procedures

  Section 6  Automatic Dependent Surveillance Procedures

  Section 7  Emergency and Non-Routine Procedures

  Section 8  Pacific FANS-1/A Implementation

  Section 9  Continental CPDLC Implementation

  Section 10 Index

  Section 11 Endnotes
  ---------- ------------------------------------------------------------

## Document Management

This document is owned and managed by the FANS Interoperability Teams
(FITs) of the Informal Pacific ATC Coordinating Group (IPACG), and the
Informal South Pacific ATC Coordinating Group (ISPACG). The POM editor,
working with the ISPACG and IPACG contact points is:

Reed B. Sladen

Special Assistant -- Pacific, Oceanic and Offshore Integrated Product
Team

Federal Aviation Administration (FAA)

Tel: +1 510 745 3328

Fax: +1 510 745 3826

Email: [reed.b.sladen@faa.gov]{.underline}

The IPACG principle contact point is:

Yoshiki Imawaka, IPACG/FIT Co-chair

Special Assistant to the Director, Office of Aeronautical Satellite
Systems

Japan Civil Aviation Bureau (JCAB)

Ministry of Land, Infrastructure and Transport

Tel: +81 3 5253 8743

Fax: +81 3 5253 1663

Email: <imawaka-y2ys@mlit.go.jp>

The ISPACG principle contact point is:

Mark Goodall

Oceanic Service Delivery Manager

Airways Corporation of New Zealand

Tel: +64 9 256 8078

Fax: +64 9 275 3106

Email: <goodallm@airways.co.nz>

## Copies

Paper copies are no longer distributed. There are four "controlled
copies" and they can be found at any of the following web sites:

[http://www.crasa.cra-japan.org](http://www.crasa.cra-japan.org/) (the
JCAB CRASA web page)

<http://www.faa.gov/ats/ato/130.htm> (the FAA's Oceanic Procedures
Branch)

<http://www.faa.gov/ats/ato/ipacg.htm> (the IPACG web page)

<http://www.faa.gov/ats/ato/ispacg.htm> (the ISPACG web site)

Copies may be freely downloaded from the web sites in a zip file, or
electronic copies may be requested from one of the three people above
via e-mail

## Changes to the POM

Whenever a user identifies a need for a change to this document, a
Request for Change Form (RFC) (see Section 1.6 below) should be
completed and submitted to any of the three individuals listed above.

When an RFC has been approved by both the IPACG and ISPACG FITs then a
new version of the POM will be published, with the changes marked by an
"\|" in the margins, and an endnote indicating the relevant RFC, in case
the reader wants to actually see the origin of the change. If the change
is in a table cell, the outside edges of the table will be highlighted:

  ----------------------- ----------------------- -----------------------
                                                  

  ----------------------- ----------------------- -----------------------

In those few cases where a change is initiated by the editor and has to
do with document format rather than functional content, the change may
not have an associated RFC, but the change will be marked and annotated
in the same way.[^1]

## Editing conventions

When referring to CPDLC messages in the text of the document, the
following conventions are used:

  --------------------------------------------------- ---------------------------
  Pre-formatted message elements are represented by   **[contact]{.smallcaps}**
  bold small capitals                                 

  Variable fields in pre-formatted message elements   **\[icaounitname\]**
  are represented by bold lower case characters in    
  square brackets                                     

  Free text message elements are represented by       Select ATC Comm Off
  normal characters:                                  
  --------------------------------------------------- ---------------------------

+----------------------------------------------------+-------+--------+
| ##  Request For Change form                        | **RFC |        |
|                                                    | Nr:** |        |
+----------------------------------------------------+-------+--------+

To be used whenever requesting a change to any part of POM. This form
may be photocopied as required.

  -------------------- --------- --- ---------------------- ----------- -----------
  **1. SUBJECT:**                                                       

                                                                        

  **2. REASON FOR                                                       
  CHANGE:**                                                             

                                                                        

  **3. DESCRIPTION OF                                                   
  PROPOSAL: \[attach                                                    
  additional pages if                                                   
  necessary\]**                                                         

                                                                        

  **4. REFERENCE(S):**                                                  

  **5. PERSON                                               **DATE:**   
  INITIATING:**                                                         

  **ORGANISATION:**                                                     

  **TEL/FAX/EMAIL:**                                                    
  -------------------- --------- --- ---------------------- ----------- -----------

  ---------------- -------------------- -------------------- -------------------- -------------- -- -----------
  **6.                                  **RESPONSE DUE BY                                           
  CONSULTATION**                        DATE:**                                                     

                   **Organisation**     **Name**             **Agree/Disagree**                     **Date**

                                                                                                    

  **7. ACTION                                                                                       
  REQUIRED:**                                                                                       

  **8. POM                                                                        **DATE            
  EDITOR**                                                                        REC'D:**          

  **9. FEEDBACK                                                                   **DATE:**         
  PASSED**                                                                                          
  ---------------- -------------------- -------------------- -------------------- -------------- -- -----------

## Amendment Record

  ------------ ------------- ------------ --------------------------------
  **Version /  **Date**      **Amended    **Comments**
  Amendment                  by**         
  Number**                                

  1.0          07 October                 This is the original version
               2002                       combining Version 2.0 of the
                                          North-Central Pacific Operations
                                          Manual (NCPOM) and Version 3.2
                                          of the South Pacific Operations
                                          Manual (SPOM). The previously
                                          coordinated intent is for
                                          adoption by ISPACG/FIT at their
                                          next meeting in February 2003.

  1.1          06 January    Editor       This version has no substantive
               2003                       changes. It merges the separate
                                          Parts into a single file.

  2.0          15 August     RFCs and     This Version incorporates all
               2003          Editor       the RFCs approved at ISPACG in
                                          March of 2003 and IPACG in July
                                          of 2003.

                                          

                                          

                                          

                                          

                                          

                                          

                                          

                                          

                                          

                                          

                                          

                                          

                                          

                                          

                                          

                                          

                                          
  ------------ ------------- ------------ --------------------------------

[^2]

# Acronym List

  ------------ ----------------------------------------------------------
  ACARS        Aircraft Communications Addressing and Reporting System

  ACAS         Aircraft Collision Avoidance System (ICAO)

  ADS          Automatic Dependent Surveillance

  AEEC         Airline Electronic Engineering Committee

  AFN          ATS Facilities Notification

  AIP          Aeronautical Information Publication

  AOC          Airline Operational Communications

  APANPIRG     Asia/Pacific Air Navigation Planning and Implementation
               Regional Group

  ARINC        Aeronautical Radio Incorporate

  ATC          Air Traffic Control

  ATM          Air Traffic Management

  ATS          Air Traffic Services

  ATSU         ATS unit

  AVICOM       AVICOM Japan Co. LTD

               

  CNS          Communications, Navigation, Surveillance

  CPDLC        Controller Pilot Data Link Communications

  CRA          Central Reporting Agency

  CRASA        CRA Support Agency

               

  DL           Downlink message

               

  EUROCAE      European Organisation for Civil Aviation Equipment

               

  FAA          Federal Aviation Administration

  FANS         Future Air Navigation System

  FIR          Flight Information Region

  FIT          FANS Interoperability Team

  FMC          Flight Management Computer

  FMS          Flight Management System

               

  GES          Ground Earth Station (satellite)

  GPS          Global Positioning System (USA)

               

  HF           High Frequency (3-30 Mhz)

               

  IATA         International Air Transport Association

  ICAO         International Civil Aviation Organisation

  IFATCA       International Federation of Air Traffic Controllers
               Associations

  IFALPA       International Federation of Air Line Pilots' Associations

  IPACG        Informal Pacific ATC Coordinating Group

  ISPACG       Informal South Pacific ATS Coordinating Group

               

  JCAB         Civil Aviation Bureau Japan

               

  MCDU         Multipurpose Control Display Unit (ACARS & FMC)

  MU           Management Unit (ACARS)

               

  NCPOM        North-Central Pacific Operations Manual

  NDA          Next Data Authority

  NOTAM        NOtice To AirMen

               

  OCS          Oceanic Control System (Datalink system for the Auckland
               FIR)

  ODL          Oceanic Data Link (Datalink system for the Oakland FIR)

  ODP          Oceanic Air Traffic Control Data Processing System
               (Datalink system for the Tokyo FIR)

               

  RNP          Required Navigation Performance

  RTCA         RTCA Inc.

  RVSM         Reduced Vertical Separation Minima

               

  SATCOM       Satellite Communication

  SATVOICE     Satellite Voice Communication

  SEAC         Service d'Etat de l'Aviation Civile (French Polynesia)

  SITA         Société Internationale de Télécommunications Aéronautiques

  SPOM         South Pacific Operations Manual

  SR&O         System Requirements and Objectives (FANS-1 document)

               

  TCAS         Traffic Alert and Collision Avoidance System (USA)

               

  UL           Uplink message

               

  VHF          Very High Frequency (30-300 Mhz)

  VIVO         Visualisation des Vols Océaniques (Situation display &
               datalink system for the Tahiti FIR)
  ------------ ----------------------------------------------------------

# System Integrity and Monitoring

## Introduction

The FANS-1/A CNS/ATM environment is an integrated system including
physical systems (hardware, software,[^3]

and communication networks), human elements (pilots and controllers),
and the procedures for use by pilots and controllers.

Because of the integrated nature of the system and the degree of
interaction among its components, end to end system monitoring is
required. The procedures described in this section aim to ensure end to
end system integrity by validation and the identification, reporting and
tracking of problems revealed by monitoring.

These procedures do not replace the ATS incident reporting procedures
and requirements, as specified in *ICAO*

*PANS/ATM*, Appendix 4; *ICAO Air Traffic Services Planning Manual (Doc
9426)*, Chapter 3; or applicable[^4]

State regulations, affecting the parties directly involved in a
potential ATS incident.

## Personnel Licensing and Training

Prior to operating ATC data link communications equipment, pilots and
controllers shall receive appropriate training in accordance with Annex
1 and Annex 6 to the Convention on International Civil Aviation.

Notwithstanding the above requirement, special arrangements may be made
directly between an operator and ATSU for the purposes of undertaking
trials of ATC data link equipment.

## Reference Documents

+---+--------------------------+----------+-------+-----------+-------+
| * | **Name of the document** | **Ref    | **D   | *         | **Dom |
| * |                          | erence** | ate** | *Origin** | ain** |
| I |                          |          |       |           |       |
| d |                          |          |       |           |       |
| * |                          |          |       |           |       |
| * |                          |          |       |           |       |
+---+--------------------------+----------+-------+-----------+-------+
| 1 | Air Traffic Services     | D926U068 | Apr   | Boeing    | CPDLC |
|   | System Requirements and  |          | 97    |           |       |
|   | Objectives - Generation  | R        |       |           | ADS   |
|   | 2 (B747-400)             | evision- |       |           |       |
|   |                          |          |       |           | AFN   |
|   | (ATS SR&O)               |          |       |           |       |
+---+--------------------------+----------+-------+-----------+-------+
| 2 | Interoperability         | DO-258 / | Sep   | RTCA and  | CPDLC |
|   | Requirements for ATS     | ED-100   | 00    | EUROCAE   |       |
|   | Applications using ARINC |          |       |           | ADS   |
|   |                          |          |       |           |       |
|   | 622 Data Communications  |          |       |           | AFN   |
+---+--------------------------+----------+-------+-----------+-------+
| 3 | Air Traffic Services     | MDC      | Jan   | Boeing    | CPDLC |
|   | System Requirements &    | 99K9005  | 00    |           |       |
|   | Objectives for the MD90  |          |       |           | ADS   |
|   | (ATS SR&O)               | Revision |       |           |       |
|   |                          | A        |       |           | AFN   |
+---+--------------------------+----------+-------+-----------+-------+
| 4 | Air Traffic Services     | D        | Nov   | Boeing    | CPDLC |
|   | System Requirements and  | 926T0240 | 98    |           |       |
|   | Objectives - Generation  |          |       |           | ADS   |
|   | 1 (B757/B767)            |          |       |           |       |
|   |                          |          |       |           | AFN   |
|   | (ATS SR&O)               |          |       |           |       |
+---+--------------------------+----------+-------+-----------+-------+
| 5 | Air Traffic Services     | D243     |       | Boeing    | CPDLC |
|   | Systems Requirements and | W018-11, |       |           |       |
|   | Objectives - Generation  | Revision |       |           | ADS   |
|   | 3 (B777)                 | A        |       |           |       |
|   |                          |          |       |           | AFN   |
|   | (ATS SR&O)               |          |       |           |       |
+---+--------------------------+----------+-------+-----------+-------+
| 6 | AIM-FANS System          | 464.0840 | Apr   | Airbus    | CPDLC |
|   | Objectives &             | / 95     | 97    |           |       |
|   | Requirements (South      |          |       |           | ADS   |
|   | Pacific Oceanic          | Issue 4  |       |           |       |
|   | Operations in an AEEC    |          |       |           | AFN   |
|   | 622 Environment)         |          |       |           |       |
+---+--------------------------+----------+-------+-----------+-------+
| 7 | Air Traffic Services     | MDC      | Jan   | Boeing    | CPDLC |
|   | Systems Requirements and | 99K1108  | 00    |           |       |
|   | Objectives for the MD10  | --       |       |           | ADS   |
|   | (ATS SR&O)               | Revision |       |           |       |
|   |                          | -        |       |           | AFN   |
+---+--------------------------+----------+-------+-----------+-------+
| 8 | Air Traffic Services     | MDC      | Aug   | Boeing    | CPDLC |
|   | Systems                  | 00K9010  | 00    |           |       |
|   |                          |          |       |           | ADS   |
|   | Requirements and         | Revision |       |           |       |
|   | Objectives for the B717  | A        |       |           | AFN   |
|   | (ATS SR&O)               |          |       |           |       |
+---+--------------------------+----------+-------+-----------+-------+
| 9 | Air Traffic Services     | MDC      | Not   | Boeing    | CPDLC |
|   | Systems Requirements and | 00K1022  | yet   |           |       |
|   | Objectives for the MD11  |          | is    |           | ADS   |
|   | (ATS SR&O)               | Revision | sued. |           |       |
|   |                          | -        |       |           | AFN   |
+---+--------------------------+----------+-------+-----------+-------+
| 1 | Interoperability         | DO-258/  | Sep   | RTCA and  | CPDLC |
| 0 | Requirements for ATC     |          | 00    | EUROCAE   |       |
|   | Applications using ARINC | ED-100   |       |           | ADS   |
|   | 622 Data Communications  |          |       |           |       |
|   |                          |          |       |           | AFN   |
+---+--------------------------+----------+-------+-----------+-------+
| 1 | Air Traffic Services     |          |       |           |       |
| 1 | Systems Requirements and |          |       |           |       |
|   | Objectives for the C-5B  |          |       |           |       |
|   | (ATS SR&O)               |          |       |           |       |
+---+--------------------------+----------+-------+-----------+-------+
| 1 | Air Traffic Services     |          |       |           |       |
| 2 | Systems Requirements and |          |       |           |       |
|   | Objectives for the       |          |       |           |       |
|   | KC-10A (ATS SR&O)        |          |       |           |       |
+---+--------------------------+----------+-------+-----------+-------+

## System Performance Criteria

The table below defines the minimum values to be met and verified. This
does not prevent the ATS service providers from negotiating more
constraining contractual requirements with their communication service
providers if it is thought necessary.

+------------+------------------------------------------+-------------+
| **         | **Definition**                           | **Values**  |
| Criteria** |                                          |             |
+------------+------------------------------------------+-------------+
| **Perf     | End to end round trip time for uplinks.  | Round trip  |
| ormances** | (sending and reception of MAS)           | time of 2   |
|            |                                          | minutes,    |
|            |                                          | 95% of the  |
|            |                                          | messages.   |
|            |                                          |             |
|            |                                          | Round trip  |
|            |                                          | time of 6   |
|            |                                          | minutes,    |
|            |                                          | 99% of the  |
|            |                                          | messages.   |
+------------+------------------------------------------+-------------+
|            | End to end one way time for downlinks.   | One way     |
|            | (comparison of message time stamp and    | time of 1   |
|            | receipt time)                            | minute, 95% |
|            |                                          | of the      |
|            |                                          | messages.   |
|            |                                          |             |
|            |                                          | One way     |
|            |                                          | time of 3   |
|            |                                          | minutes,    |
|            |                                          | 99% of the  |
|            |                                          | messages    |
+------------+------------------------------------------+-------------+
|            | Uplink messages only: Undelivered        | Less than   |
|            | messages will be determined by:          | 1% of all   |
|            |                                          | attempted   |
|            | -   Message assurance failure is         | messages    |
|            |     received. After trying both VHF and  | undelivered |
|            |     SATCOM. Depending on reason code     |             |
|            |     received, the message might, in      |             |
|            |     fact, have made it to the aircraft.  |             |
|            |                                          |             |
|            | -   No message assurance or flight crew  |             |
|            |     response is received by ATSU after   |             |
|            |     900 seconds                          |             |
+------------+------------------------------------------+-------------+
| **Avai     | The ability of the network data link     | 99.9%       |
| lability** | service to perform a required function   |             |
|            | under given conditions at a given time:  | TBD         |
|            |                                          |             |
|            | The maximum allowed time of continuous   |             |
|            | unavailability or downtime should be     |             |
|            | declared (MTTR) ∗                        |             |
+------------+------------------------------------------+-------------+
| **Rel      | The ability of a data link               | TBD         |
| iability** | application/system to perform a required |             |
|            | function under given conditions for a    |             |
|            | given time interval: it can be expressed |             |
|            | in MTBF (Mean Time Between failure) ∗    |             |
+------------+------------------------------------------+-------------+
| **I        | The probability of an undetected         | 10^-6^/hour |
| ntegrity** | failure, event or occurrence within a    |             |
|            | given time interval.                     |             |
+------------+------------------------------------------+-------------+

∗ Availability = MTBF x 100/(MTBF+MTTR)

*Note: RTCA SC189/EUROCAE WG 53 is defining the performance requirements
for specific operational environments.*

##  ATC System Validation 

To meet system integrity requirements, States shall consider a
validation process that confirms the integrity of their equipment and
procedures. The processes shall include:

a)  A system safety assessment which demonstrates that the ATS
    Provider's system will meet the safety objectives;

b)  Integration test results confirming interoperability for operational
    use of airborne and ground systems; and

c)  Confirmation that the ATS Operation Manuals are compatible with
    those of adjacent providers.

### System safety assessment

The system safety assessment can be achieved through a functional hazard
analysis or a documented system safety case. This should be conducted
for initial implementation as well as for future enhancements and should
include:

a)  Identifying failure conditions;

b)  Assigning levels of criticality;

c)  Determining probabilities for occurrence; and

d)  Identifying mitigating measures.

Following on from the safety assessment, States should institute
measures to offset the identified failure conditions, or reduce the
probability of their occurrence to an acceptable level. This could be
accomplished through automation or procedures.

### Integration test 

States should conduct trials with aircraft to ensure that they meet the
technical requirements for interoperability previously specified in this
document.

### ATS operation manuals

States should coordinate with adjacent States to confirm that their ATS
Operation Manuals contain standard operating procedures.

### ATS SYSTEM INTEGRITY

With the implementation of automated ATS control systems, data changes,
software upgrades, and system failures can impact on adjacent units.

a\) ATSUs shall ensure that suitable procedures are in place to ensure
that data is correct and accurate, including any changes thereto, and
that security of such data is not compromised.

b\) ATSUs shall also formalise procedures for timely notification to
adjacent units of system failures, software upgrades (or downgrades) or
other changes, which may impact on surrounding ATS units. Such
notification procedures will normally be detailed in Letters of
Agreement between adjacent units.[^5]

## System Monitoring

Routine collection of data is necessary in order to ensure that the
system continues to meet its performance, safety and interoperability
requirements, and that operations and procedures are working as planned.
The monitoring program is a two-fold process. First, summary statistical
data should be produced periodically showing the performance of the
system. This is accomplished through FANS-1/A Periodic Status Reports.
In addition, as problems or abnormalities arise, they should be
identified, tracked, analyzed, corrected and information disseminated as
required, utilizing the FANS-1/A Problem Report. This process should
remain in effect until the system conforms as planned.

### The monitoring process

When problems or abnormalities are discovered, the initial analysis
should be performed by the organization(s) identifying the problem. In
addition, a copy of the problem report should be sent to the Central
Reporting Agency (CRA) which will assign a tracking number. As some
problems or abnormalities may involve more than one organization, the
originator should be responsible for follow-up action to rectify the
problem and forward the information to the CRA. It is essential that all
information relating to the problem is documented and recorded and
resolved in a timely manner.

The parties who need to be involved in this monitoring process and
problem tracking for the review and analysis of the data collected are:

a)  ATS service providers or organizations responsible for ATS system
    maintenance (where different from the ATS provider);

b)  State regulatory authorities;

c)  Communication service providers;

d)  Aircraft operators; and

e)  Aircraft and avionics manufacturers.

### Dispatch of confidential information

It is important that information that may have an operational impact on
other parties be distributed to all users as soon as possible. In this
way, each party is made aware of problems already encountered by others,
and may be able to contribute further information to aid in the solution
of these problems. Before dissemination of information, all references
that could identify particular parties are removed by the CRA.

### FANS-1/A problem reports

Problem reports may originate from many sources, but most will fall
within two categories; reports based on observation of one or more
specific events, or reports generated from the routine analysis of data.
For example, a problem report could arise from an incident where there
was confusion about the meaning of a clearance, as the result of
inappropriate use of free text. The user would document the problem,
resolve it with the appropriate party and forward a copy of the report
to the CRA for tracking. This one incident may appear to be an isolated
case, but the receipt of numerous similar reports by the CRA that could
indicate an area that needs more detailed examination.

To effectively resolve problems and track progress, the forms should be
sent to the nominated point of contact at the appropriate organization
and the CRA. The resolution of the identified problems may require:

a)  Re-training of system operators, or revision of training procedures
    to ensure compliance with existing procedures;

b)  Change to operating procedures;

c)  Change to system requirements, including performance and
    interoperability; or

d)  Change to system design.

### FANS-1/A periodic status report

The ATS Providers should complete the FANS-1/A Periodic Status Report at
specified intervals agreed by the regional FANS Interoperability Team
(FIT) for the dissemination of information and as an indication of
system performance. Additionally, the report should identify any trend
discovered in system deficiencies, the resultant operational
implications, and the resolution, if applicable.

Communications service providers are also expected to submit FANS-1/A
Periodic Status Reports on the performance of their networks at
specified intervals. These reports may contain planned or current
upgrades to the systems and may not be required as often as the reports
from ATS providers.

### Processing of reports

Each party to the monitoring process should nominate a single point of
contact for receipt of problem reports and coordination with the other
parties. This list should be distributed to all parties to the
monitoring process.

Each State should establish mechanisms within its ATS provider and
regulatory authority to:

a)  Assess problem reports and refer them to the appropriate technical
    or operational expertise for investigation and resolution;

b)  Coordinate with communication service providers and aircraft
    manufacturers;

c)  Develop interim operational procedures to mitigate the effects of
    problems until such time as the problem is resolved;

d)  Monitor the progress of problem resolution;

e)  Prepare summaries of problems encountered and their operational
    implications and forward these to the central reporting agency; and

f)  Prepare the FANS-1/A periodic status report at pre-determined times
    and forward these to the Central Reporting Agency.

## FANS Interoperability Team

The FANS Interoperability Team (FIT) shall oversee the monitoring
process to ensure the FANS-1/A system continues to meet its performance,
safety, and interoperability requirements and that operations and
procedures are working as planned. The FIT:

a)  Reviews de-identified problem reports and determine appropriate
    resolution;

b)  Develops interim operational procedures to mitigate the effects of
    problems until such time as they are resolved;

c)  Monitors the progress of problem resolution;

d)  Prepares summaries of problems encountered and their operational
    implications;

e)  Assesses system performance based on information in CRA periodic
    reports;

f)  Authorizes and coordinates system testing.

FIT members are listed at Section 8.

## Central Reporting Agency

The Central Reporting Agency (CRA) is an organization tasked with the
regular dissemination of de-identified statistical data based on monthly
status reports received from FIT members. The CRA tracks problem reports
and publishes de-identified information from those reports for
dissemination to FIT members. Problem resolution is the responsibility
of the appropriate FIT members.

The CRA:

a)  Prepares consolidated problem summaries, with references to
    particular States and operators removed, for dissemination to all
    interested parties;

b)  Collects and consolidates FANS-1/A Periodic Status Reports and
    disseminates these to all interested parties;

c)  Examines all data to identify trends; and

d)  Prepares an annual report for the FIT. Following review by the FIT,
    the report will be presented to APANPIRG by the IPACG/ISPACG
    Co-chairs. This report contains:

-   A summary of the system performance based on the periodic status
    reports;

-   A summary of the numbers and categories of problems reported; and

-   A report of progress with rectification of significant problems.

CRA members are listed at Section 8.

## Local Data Recording and Analysis

### Data recording

ATS providers and communication service providers shall retain the
records defined below for at least 15 days to allow for
accident/incident investigation purposes. (The providers are strongly
encouraged to retain the records for at least 30 days.) These records
shall be made available for air safety investigative purposes on demand.

These recordings shall allow replaying of the situation and
identification of the messages that were sent or received by the ATS
system.

### Local data collection

+----------------+-------------+---------------+-----------+---------+
| **             | *           | **            | **Ats     | **Air   |
| Requirements** | *Who/What** | Communication | Pr        | lines** |
|                |             | Service       | oviders** |         |
|                |             | Providers**   |           |         |
+----------------+-------------+---------------+-----------+---------+
| Operational    | Time        | Y (Every      | Y (End    | Y       |
| Procedures     | stamped ATS | message going | System)   |         |
|                | messages    | through)      |           | N       |
|                | with        |               | Y         |         |
|                | ide         | Y             |           | Y       |
|                | ntification |               | Y         |         |
|                | and         | N             |           |         |
|                | reference   |               |           |         |
|                | numbers     |               |           |         |
|                |             |               |           |         |
|                | Message     |               |           |         |
|                | Assurance   |               |           |         |
|                |             |               |           |         |
|                | Anomaly     |               |           |         |
|                | event       |               |           |         |
|                | report      |               |           |         |
+----------------+-------------+---------------+-----------+---------+
| Performance    | A           | Y             | Y (End    | Y       |
|                | vailability |               | System)   | (A      |
|                |             | Y             |           | vionics |
|                | Transit     |               | Y         | / Link  |
|                | times       |               |           | with    |
|                |             |               |           | GES)    |
|                |             |               |           |         |
|                |             |               |           | Y       |
+----------------+-------------+---------------+-----------+---------+
| Safety (i.e.   | Time        | Y (Every      | Y         | Y       |
| operational,   | stamped ATS | message going |           |         |
| performance,   | messages    | through)      | Y         | Y       |
| in             | with        |               |           |         |
| teroperability | ide         | Y             |           |         |
| requirements   | ntification |               |           |         |
| which are used | and         |               |           |         |
| to mitigate    | reference   |               |           |         |
| the effect of  | numbers/MAS |               |           |         |
| a failure      |             |               |           |         |
| condition)     | Anomaly     |               |           |         |
|                | event       |               |           |         |
|                | reports     |               |           |         |
+----------------+-------------+---------------+-----------+---------+
| In             | Time        | Y (Every      | Y         | N       |
| teroperability | stamped ATS | message going |           |         |
|                | messages    | through)      |           |         |
|                | with        |               |           |         |
|                | ide         |               |           |         |
|                | ntification |               |           |         |
|                | and         |               |           |         |
|                | reference   |               |           |         |
|                | numbers/MAS |               |           |         |
+----------------+-------------+---------------+-----------+---------+

+----------------+----------------+----------------+----+------------+
| ## FANS-1/A    |                |                |    | **Number** |
| Problem Report |                |                |    |            |
+----------------+----------------+----------------+----+------------+
|                |                |                |    |            |
+----------------+----------------+----------------+----+------------+
| **Date UTC**   |                | **Time UTC**   |    |            |
+----------------+----------------+----------------+----+------------+
| **             |                | **Flight       |    |            |
| Registration** |                | Number**       |    |            |
+----------------+----------------+----------------+----+------------+
| **Sector**     |                |                |    |            |
+----------------+----------------+----------------+----+------------+
| **Originator** |                | **Aircraft     |    |            |
|                |                | Type**         |    |            |
+----------------+----------------+----------------+----+------------+
| **             |                |                |    |            |
| Organization** |                |                |    |            |
+----------------+----------------+----------------+----+------------+
| **Active       |                | **Next         |    |            |
| Center**       |                | Center**       |    |            |
+----------------+----------------+----------------+----+------------+
| **Position**   |                |                |    |            |
+----------------+----------------+----------------+----+------------+
| *              |                |                |    |            |
| *Description** |                |                |    |            |
+----------------+----------------+----------------+----+------------+

### Description of fields

+-------------+--------------------------------------------------------+
| **Field**   | **Meaning**                                            |
+-------------+--------------------------------------------------------+
| Number      | A unique identification number assigned to this        |
|             | problem report. Organizations writing problem reports  |
|             | are encouraged to maintain their own internal list of  |
|             | these problems for tracking purposes. Once the         |
|             | problems have been reported to the CRA and             |
|             | incorporated in the database, a number will be         |
|             | assigned by the CRA and used for tracking by the FIT.  |
+-------------+--------------------------------------------------------+
| Date UTC    | UTC date when the event occurred.                      |
+-------------+--------------------------------------------------------+
| Time UTC    | UTC time (or range of times) at which the event        |
|             | occurred..                                             |
+-------------+--------------------------------------------------------+
| R           | Registration number (tail number) of the airplane      |
| egistration | involved. This should be in exactly the same format as |
|             | was used for the logon to the ATC Center, including    |
|             | any dashes used.                                       |
+-------------+--------------------------------------------------------+
| Flight      | Flight identifier (call sign) of the flight involved.  |
| Number      | This should be in exactly the same format as was used  |
|             | for the logon to the ATC Center, including any leading |
|             | zeros in the number.                                   |
+-------------+--------------------------------------------------------+
| Sector      | The departure airport and destination airport for the  |
|             | sector being flown by the airplane involved in the     |
|             | event. These should be the ICAO identifiers of those   |
|             | airports.                                              |
+-------------+--------------------------------------------------------+
| Originator  | Point of contact at the originating organization for   |
|             | this report (usually the author).                      |
+-------------+--------------------------------------------------------+
| Aircraft    | The airplane model involved (e.g. B777 or MD11). Where |
| Type        | a dash number records a significant change to the      |
|             | equipment fit (e.g. B747-400), the dash number should  |
|             | be provided as well.                                   |
+-------------+--------------------------------------------------------+
| O           | The name of the organization (airline, ATS provider or |
| rganization | datalink service provider) that created the report.    |
+-------------+--------------------------------------------------------+
| Active      | ICAO identifier of the ATC Center controlling the      |
| Center      | airplane at the time of the event.                     |
+-------------+--------------------------------------------------------+
| Next Center | If the problem involves a handover between ATC         |
|             | Centers, or occurs close to the time of a handover,    |
|             | then this should contain the ICAO identifier of the    |
|             | Center to which control was being handed over.         |
+-------------+--------------------------------------------------------+
| Position    | Location of the airplane at the time of the event.     |
|             | This could be the latitude and longitude, but could    |
|             | also be specified relative to a waypoint on the route  |
|             | or an FIR boundary.                                    |
+-------------+--------------------------------------------------------+
| Description | This should provide as complete a description of the   |
|             | situation leading up to the problem as is possible.    |
|             | Where the organization reporting the problem is not    |
|             | able to provide all the information (e.g. the          |
|             | controller may not know everything that happens on the |
|             | airplane), it would be helpful if they would           |
|             | coordinate with the other parties to obtain the        |
|             | necessary information.                                 |
|             |                                                        |
|             | The description should include:                        |
|             |                                                        |
|             | -   A complete description of the problem that is      |
|             |     being reported                                     |
|             |                                                        |
|             | -   The route contained in the FMS                     |
|             |                                                        |
|             | -   Any flight deck indications, including EICAS       |
|             |     messages that occurred                             |
+-------------+--------------------------------------------------------+
|             | -   Any MCDU scratchpad messages that occurred         |
|             |                                                        |
|             | -   Any indications provided to the controller when    |
|             |     the problem occurred                               |
|             |                                                        |
|             | -   Any problems being experienced with other datalink |
|             |     systems (such as AOC), or indications that those   |
|             |     other systems were unaffected                      |
|             |                                                        |
|             | -   Any additional information that the originator of  |
|             |     the problem report considers might be helpful but  |
|             |     is not included on the list above                  |
|             |                                                        |
|             | [If necessary to contain all the information,          |
|             | additional pages may be added, and if the originator   |
|             | considers it might be helpful, diagrams and other      |
|             | additional information (such as printouts of message   |
|             | logs) may be appended to the report.]{.smallcaps}      |
+-------------+--------------------------------------------------------+

+----------------------------+-------------+-------------+-------------+
| ## FANS-1/A P              |             |             |             |
| eriodic Status Report Form |             |             |             |
+----------------------------+-------------+-------------+-------------+
| **Originating              |             |             |             |
| Organization**             |             |             |             |
+----------------------------+-------------+-------------+-------------+
| **Date of submission**     |             | **O         |             |
|                            |             | riginator** |             |
+----------------------------+-------------+-------------+-------------+
| **Status for               |             |             |             |
| \[Month/Year\]**           |             |             |             |
+----------------------------+-------------+-------------+-------------+
| **Performance Measure**    | **Data**    |             |             |
+----------------------------+-------------+-------------+-------------+
| **[DELAY]{.underline}**    | **All times |             |             |
|                            | will be     |             |             |
|                            | calculated  |             |             |
|                            | "less than" |             |             |
|                            | \< the time |             |             |
|                            | band to the |             |             |
|                            | right.**    |             |             |
+----------------------------+-------------+-------------+-------------+
| **[Uplinks:]{.underline}** | **Number of |             |             |
|                            | messages    |             |             |
| **Round-trip transit delay | with a      |             |             |
| time**                     | round trip  |             |             |
|                            | transit     |             |             |
| (ATS Provider - delay      | delay time  |             |             |
| between the time a message | of less     |             |             |
| is sent and the time the   | than X      |             |             |
| Message Assurance (MAS)    | seconds:**  |             |             |
| referring to this message  |             |             |             |
| is received)               | X= 10s 20s  |             |             |
|                            | 30s 60s 90s |             |             |
| (Network provider - delay  | 120s 180s   |             |             |
| between the time a message | [\>]{.und   |             |             |
| arrives at the router and  | erline}180s |             |             |
| the time the MAS referring |             |             |             |
| to this message arrives    | Total       |             |             |
| back at the router)        | number of   |             |             |
|                            | uplink      |             |             |
|                            | messages:   |             |             |
|                            |             |             |             |
|                            | Total       |             |             |
|                            | number of   |             |             |
|                            | **lost**    |             |             |
|                            | uplink      |             |             |
|                            | messages:   |             |             |
+----------------------------+-------------+-------------+-------------+
| **                         | **Number of |             |             |
| [Downlinks:]{.underline}** | messages    |             |             |
|                            | with a      |             |             |
| (ATS Provider - difference | downlink    |             |             |
| between embedded message   | transit     |             |             |
| time stamp and time        | delay time  |             |             |
| message received from      | of less     |             |             |
| Network provider)          | than Y      |             |             |
|                            | seconds:**  |             |             |
| Lost messages determined   |             |             |             |
| by:                        | Y= 10s 15s  |             |             |
|                            | 30s 45s 60s |             |             |
| -   Message assurance      | 90s         |             |             |
|     failure is received.   | [\>]{       |             |             |
|     After trying both VHF  | .underline} |             |             |
|     and SATCOM. Depending  | 90s         |             |             |
|     on reason code         |             |             |             |
|     received, the message  | Total       |             |             |
|     might, in fact, have   | number of   |             |             |
|     made it to the         | downlink    |             |             |
|     aircraft.              | messages:   |             |             |
|                            |             |             |             |
| ```{=html}                 | Total       |             |             |
| <!-- -->                   | number of   |             |             |
| ```                        | **lost**    |             |             |
| -   No message assurance   | downlink    |             |             |
|     or flight crew         | messages:   |             |             |
|     response is received   |             |             |             |
|     by ATSU after 900      |             |             |             |
|     seconds                |             |             |             |
+----------------------------+-------------+-------------+-------------+

+----------------------------+-----------------------------------------+
| **[UNA                     | For each window of unavailability, list |
| VAILABILITY]{.underline}** | start and end **times and dates**.      |
|                            | Denote if notification was given to     |
| **(Actual time windows of  | operators in each case.                 |
| scheduled outages)**       |                                         |
|                            | **From: To: Notification (Y/N) Partial  |
| **(Actual time windows of  | (Y/N)**                                 |
| unscheduled outages)**     |                                         |
|                            |                                         |
| **(ATS Providers -         |                                         |
| Instances of inability to  |                                         |
| communicate with           |                                         |
| individual aircraft)**     |                                         |
+----------------------------+-----------------------------------------+
| **[OPERATIONAL             | **CPDLC ADS**                           |
| INDICATORS]{.underline}**  |                                         |
|                            |                                         |
| **Total number of aircraft |                                         |
| with connections**         |                                         |
|                            |                                         |
| **Total number of          |                                         |
| successful connections at  |                                         |
| first attempt**            |                                         |
|                            |                                         |
| **Total number of flights  |                                         |
| unable to connect**        |                                         |
|                            |                                         |
| **Significant system       |                                         |
| changes and impact on      |                                         |
| performance.**             |                                         |
+----------------------------+-----------------------------------------+
| **[GENERAL                 |                                         |
| COMMENTS]{.underline}**    |                                         |
+----------------------------+-----------------------------------------+

# Connection Management

## Pre-Flight Phase

### Identifying data link aircraft

ATS systems use Item 10 (Equipment) of the standard ICAO flight plan to
identify an aircraft's data link capabilities. The operator is
responsible for inserting the following items in the ICAO flight plan:

-   Item 10 - The letter "J" to indicate data link capability;

-   Item 10 - The letter "D" in the Surveillance field to indicate ADS
    capability;

-   Item 18 - The letters DAT/ followed by one or more letters as
    appropriate to indicate the type of data link

equipment carried when "J" is entered in Item 10. (Refer ICAO
PANS/ATM)[^6]

Example:

ICAO Item 10: \...\....**J**\...\....**/**...**D**

ICAO Item 18: **REG/**........\...**DAT/SV** (for a satellite and VHF
data link equipped aircraft)

  ----------------------------------- -----------------------------------
  **Letter following DAT/**           **Type of data link**

  S                                   Satellite data link

  H                                   HF data link

  V                                   VHF data link

  M                                   SSR Mode S data link
  ----------------------------------- -----------------------------------

Table 1: Specifying CPDLC Capability in FPL

### Registration number

ATS systems compare the registration number of the aircraft contained in
Field 18 (Other Information) of the ICAO flight plan with the
registration contained in the AFN logon. The operator is responsible for
ensuring that the correct aircraft registration is filed in Field 18 of
the ICAO flight plan.

## The CPDLC Connection Sequence

The life sequence of a CPDLC connection according to the flight phases
is normally as follows:

![](media/image2.wmf){width="6.309722222222222in"
height="3.8583333333333334in"}

Figure 1: Life Sequence of the CPDLC Connection

## The AFN Logon

### Prerequisite for CPDLC and / or ADS connection

The AFN logon is a prerequisite to any CPDLC or ADS connection.

### Initiating an AFN logon

The AFN logon can be initiated:

-   Manually by the pilot during an \"initial logon\", or

-   By an ATSU using the address forwarding process.

### Purpose of an AFN logon

The AFN (ATS Facilities Notification) logon serves the following
purposes:

a)  To provide an ATSU with the data link application context of the
    aircraft, namely:

-   The ATS data link applications supported on board (CPDLC, ADS),

-   Their version numbers, and

-   The associated addresses (in the FANS-1/A context, these are the
    ACARS addresses unique to each aircraft).

b)  To provide an ATSU with information such as the flight
    identification and the registration number. This information will
    allow the correlation of the flight attempting to logon with the
    corresponding flight data held by the ATS system. The aircraft
    logging on will then be positively identified by the ATS system.

c)  To allow ATSUs to establish both ADS and CPDLC connections, where
    applicable.

### The initial AFN logon

The initial AFN logon is performed by the pilot manually sending an
**AFN [contact]{.smallcaps}** message (FN_CON) containing the 4
character ICAO code of the ATSU.

An initial AFN logon is required when the aircraft does not already have
an ADS or CPDLC connection, such as:

-   When the aircraft is preparing to depart from an airport and the
    first logon to a ground system is executed,

-   When the aircraft will enter a CPDLC area from an area where
    [CPDLC]{.smallcaps} services have not been provided, or

[^7]

![](media/image3.wmf)

Figure 2: Initial AFN Logon

#### Parameter time for performing the initial AFN logon

For aircraft that will enter an area where CPDLC services will be
provided and an initial logon is required, the pilot should send an AFN
Contact message (FN_CON) **between 15 and** **45 minutes** prior to
entering the area. ATSUs should ensure that an FN_CON message sent
within this time frame would be accepted by the applicable ground
system.

#### Notification of ATS variations

Any ATSU where the ground system is unable to accept an FN_CON message
sent between 15 and 45 minutes prior to the ETD or the estimate for
entering the FIR shall publish instructions notifying the parameters
during which a logon will be accepted.

#### Constructing the FN_CON message

To avoid an automatic rejection of the logon, the pilot shall ensure
that the flight identification and registration numbers contained in the
FN_CON message are [exactly the same]{.underline} as the flight
identification and registration numbers filed in the flight plan.

#### FMS and ACARS flight identification

When comparing aircraft identifiers to enable flight plan coupling with
the logon, the ATSU shall only use the flight identifier and aircraft
registration as contained within the end system (CRC\'d) portion of AFN
logon message. The flight identifier in the ACARS message header has a
different format to that required by the ground system (i.e. a two alpha
character airline identifier followed by up to four numeric characters)
and should not be used by the pilot to notify aircraft identification.

## CPDLC Connection

### Purpose CPDLC connection

The purpose of a CPDLC connection is to allow the exchange of CPDLC
messages between an aircraft and an ATSU.

### Management Of CPDLC connections

ATSUs shall manage CPDLC connections to ensure that wherever possible
the active CPDLC connection is held by the ATSU with responsibility for
the flight. Connections should be maintained and terminated to support
this requirement, however aircraft may be connected with another ATSU or
sector on occasions such as:

a)  When an aircraft is transiting a CPDLC serviceable FIR subject to
    coordination between ATSUs;

b)  During the CPDLC connection transfer process;

c)  Where the active connection is retained by the transferring ATSU
    subject to prior coordination;

d)  When the aircraft is within a non-serviceable or non-CPDLC FIR and
    logs on to the ATSU responsible for the next FIR; or[^8]

e)  In emergency circumstances.

Care must be taken not to issue clearances or instructions to a flight
via CPDLC when it is under the control of another sector/ATSU.

### CPDLC connection sequence

A CPDLC connection attempt can only occur after the AFN logon has been
completed. The CPDLC connection is initiated by sending the
**[Connection Request]{.smallcaps}** message by the ATSU and is
established when the **[Connection Confirm]{.smallcaps}** message is
received from the aircraft:

a)  If there is no existing connection, the avionics will accept this
    connection as the active connection.

b)  If there is an existing connection, the avionics will check that the
    initiating ATSU has been established as the next data authority. If
    so, the avionics will accept this connection as the non-active
    connection.

c)  In all other situations, the avionics will reject the connection
    request.

![](media/image4.wmf)

Figure 3: CPDLC Connection Sequence

### Active and inactive CPDLC connections

A CPDLC connection established between an aircraft and an ATSU is either
active or non[-]{.smallcaps}active.

a)  A connection is [active]{.underline} when CPDLC messages can be
    exchanged.

b)  A connection is [non[-]{.smallcaps}active]{.underline} when CPDLC
    messages cannot be exchanged.

FANS-1/A aircraft can have two CPDLC connections established, each with
a different ATSU. Only one of these connections can be active at any
given time. A non[-]{.smallcaps}active connection becomes active as soon
as the active connection is terminated.

#### Determination of an active CPDLC connection

When the aircraft had a CPDLC connection with the previous ATSU, there
are two ways for the controller to know if the CPDLC connection is
active:

a)  To send a message with the possibility of receiving a **[Not Current
    Data Authority]{.smallcaps}** error message if the connection is not
    yet active; or[^9]

b)  To wait until a CPDLC message is received from the pilot.

## Next Data Authority Notification

### Purpose of the NDA message 

Definition: The ATSU holding the active connection with the aircraft is
known as the 'Data Authority'.

The purpose of the Next Data Authority (NDA) message is to advise the
avionics of the next ATSU to become the Data Authority. The sending of
the NDA message is the first step in the CPDLC transfer sequence between
an aircraft and two ATSUs. The avionics will only accept a CPDLC
connection request from the ATSU quoted in the NDA message.

### Procedure for the NDA notification

The ATSU with the current active connection notifies the avionics of the
Next Data Authority by sending a **[Next Data Authority]{.smallcaps}
\[icaofacilitydesignation[\] ]{.smallcaps}**message.

![](media/image5.wmf)

Figure 4: Next Data Authority Notification

#### Sequence of the NDA and FN_CAD messages

The CPDLC connection sequence can be initiated by automated systems
immediately following the AFN logon, the NDA message shall be sent prior
to the **AFN [contact advisory]{.smallcaps}** (FN_CAD) to avoid a
rejection of the connection. The avionics must receive the NDA prior to
receiving a connection request message; otherwise the connection request
will be rejected.

#### Change of the NDA

If the next data authority should change after the NDA message has been
sent (e.g. an aircraft re-route due to weather), a new NDA message must
be sent. This new NDA will supersede the original NDA message in the
avionics and will disconnect any inactive connection already established
by the unit that had been previously designated as the Next Data
Authority. In the following diagram, an inactive connection that is
established with ATSU 2 would be dropped when a new NDA designating ATSU
3 is received.

![](media/image6.png)

Figure 5: Subsequent Next Data Authority Notification

### Abnormal cases relating to the NDA notification

If the NDA message (containing the correct Next Data Authority
designation) is not received by the avionics before receiving the
**[Connection Request]{.smallcaps}** message sent by the subsequent
ATSU, the connection request message will be rejected. The pilot has no
indication that the **[Connection Request]{.smallcaps}** has been
rejected.

#### Unsuccessful NDA delivery 

When the NDA delivery has not been successful, the controller's initial
action should be to send another NDA message. If this is also
unsuccessful, the controller shall instruct the pilot to manually
initiate an AFN logon[^10]

with the subsequent ATSU after termination of the CPDLC connection. An
**[End service]{.smallcaps}** message is not required in this case.

The phraseology to be used via CPDLC or voice will be:

+---------+------------------------------------------------------------+
| **Contr | **[Contact]{.smallcaps} \[icaounitname\] \[frequency\]**   |
| oller** |                                                            |
|         | Select ATC Com Off then Logon to \[ATSU name\]             |
|         |                                                            |
|         | ***(Note: When via CPDLC, this last element will be free   |
|         | text)***                                                   |
+---------+------------------------------------------------------------+
| **      | **[Wilco]{.smallcaps}**                                    |
| Pilot** |                                                            |
+---------+------------------------------------------------------------+

*The \[ATSU name\] is the relevant four character ICAO code.*

*Note: Instructing the pilot to Select ATC Com off will result in loss
of CPDLC connectivity. This procedure should only be applied approaching
the FIR boundary of the next ATSU.*[^11]

#### Duplication of the NDA message

Receipt by the aircraft of a second NDA message will disconnect the
non-active CPDLC connection, even if the

NDA message specifies the same (non-active) ATSU that is already
connected. Therefore, under normal circumstances, duplicate NDA messages
shall not be uplinked.[^12]

## AFN Logon Triggered By Address Forwarding

### Purpose and procedure

The Address Forwarding process is initiated by the ground system and
consists of an ATSU sending an **[AFN contact advisory]{.smallcaps}**
message (FN_CAD) to the avionics. The FN_CAD instructs the avionics to
automatically perform an AFN logon to the ATSU address included in the
message. Address Forwarding is used to allow a subsequent ATSU to
establish an inactive CPDLC connection and ADS contracts, and to allow
adjacent ATSUs to establish ADS contracts for monitoring purposes.

*Note: The FN_CAD message should be sent at least 15 minutes prior to
the estimated time of arrival at the FIR boundary.*[^13]

### An aircraft transferring from one data link area to another

![](media/image7.wmf)

Figure 6: Transfer between areas where data link is provided

The address forwarding process is invisible to the flight crew. As a
result, the flight crew does not receive an indication as to whether or
not the FN_CON or FN_AK messages have been delivered correctly. However,
the crew does receive an indication of a change to the active ATSU
following a successful CPDLC connection transfer.

### Aircraft transiting data link areas 

The CRA has found multiple examples of connection transfer failures
attributed to controllers or systems not completing all of the messaging
requirements for the connection transfer during a short transit time
across a portion of the FIR.[^14]

When an ATSU will only have jurisdiction over a data link connected
aircraft for a relatively short duration (e.g.

less than 30 minutes flying time), the requirements for the transfer of
communications for the[^15] aircraft should be coordinated between the
controlling and affected units, or covered in appropriate Letters of
Agreement between all affected ATSUs[^16]. If the ATSU

concerned requires ADS contracts to monitor the transit of the aircraft
across a portion of the FIR, but the transfer of CPDLC is not required,
the controlling unit should perform address forwarding in the order of
priority described by the following diagram.

Figure 7: Transiting data link areas

ATSU 1 should address forward to ATSU 3 (Priority 1) to ensure that a
CPDLC connection and ADS contracts are established prior to address
forwarding to ATSU 2 (Priority 2) so that ADS contracts can be
established for monitoring the transit of the aircraft across the
relevant portion of the FIR.

#### Options for initiating the AFN logon

The AFN logon may be initiated by one of the following options.

a)  *Option 1 - Initial AFN [Logon:]{.smallcaps}* [CPDLC]{.smallcaps}
    shall cease between the aircraft and ATSU 1. The aircraft will enter
    ATSU 2 using voice. Pilots should initiate an initial AFN logon to
    ATSU 3 between 15 and 45 minutes prior to the estimated time at the
    FIR boundary.

b)  *Option 2 - AFN [Logon]{.smallcaps} triggered by address
    forwarding:* Address forwarding may be used to \"jump\" the
    connections over a FIR not requiring a CPDLC connection when agreed
    by the appropriate ATSUs. In this circumstance the controller shall
    inform the pilot of this intention by appending the freetext message
    CONTACT WITH \[ATSU name\] NOT REQUIRED to the frequency transfer
    instructions For example: AT TEKEP MONITOR NADI CENTER 13261.
    CONTACT WITH AUCKLAND NOT REQUIRED.[^17]

#### Transferring CPDLC for short transits

Where an ATS Unit decides to accept the transfer of data link for a
short transit across its FIR, the receiving controller needs to be aware
of whether any automated transfer process to the subsequent unit will be
affected by the relatively short transit period across the FIR.

If so, then the controller must ensure that all messages required to
successfully transfer the connections to the next unit (e.g. NDA,
Address Forwarding, Monitor/Contact information, and End Service
messages) are sent in the proper sequence at the correct time, whether
they are sent automatically by the system or manually by the controller.

Note: The receiving unit must also be the Current Data Authority (CDA)
before any of these messages can be sent successfully. For example, if
the receiving unit tries to send the NDA message prior to becoming the
CDA to account for a short transit time, the messages will fail.[^18]

## End of Service and CPDLC Connection Transfer

### Purpose and procedure 

Under normal conditions, the current ATSU initiates the CPDLC connection
termination sequence by sending an **[End Service]{.smallcaps}** uplink
message. In response to an **[End Service]{.smallcaps}** message:

-   The avionics will downlink a **[Disconnect]{.smallcaps}** message.
    The avionics will consider the aircraft to be disconnected as soon
    as the **[Disconnect]{.smallcaps}** message is sent.

-   The current connection will be terminated, activating the non-active
    connection. The subsequent ATSU will now be able to exchange CPDLC
    messages with the aircraft.

The success of the CPDLC transfer is dependent upon the next ATSU
establishing its own CPDLC connection prior to the **[End
Service]{.smallcaps}** message being received by the aircraft. Failure
of the next ATSU to establish a CPDLC connection before the **[End
Service]{.smallcaps}** reaches the aircraft will leave the aircraft
without CPDLC connectivity.

There are two cases in which the avionics will terminate established
CPDLC connections.

-   Depending on the software load, when any uplink messages remain open
    when the aircraft receives an End Service. [^19]

-   When the **[End Service]{.smallcaps}** element is part of a
    multi-element message where none of the elements require a
    **[Wilco]{.smallcaps}** response.

In both cases an error message will be generated to both ATS systems.

If any downlink messages remain open when the aircraft receives an
**[End Service]{.smallcaps}** message, the avionics will close the
messages and terminate the CPDLC connection with the current ATSU. This
will not affect the CPDLC connection with the next ATSU.

#### Uplink messages to be closed before the [End Service]{.smallcaps}

The controller shall ensure that no open uplink CPDLC messages exist
prior to the uplinking of an **[End]{.smallcaps}**

**[Service]{.smallcaps}** message. In the event that a CPDLC uplink is
unanswered, ATC should uplink the freetext:

CHECK ATC LOG PAGE FOR OPEN MESSAGES[^20]

#### Use of Contact/Monitor Uplink Message

The purpose of the Contact/Monitor uplink messages (UL#117 to UL#122) is
to advise the pilot when (and where) a change to the nominated frequency
is required. When any of the "Monitor" uplink messages are received the
pilot shall change to the nominated frequency at the appropriate time. A
check call is not required on the frequency. When any of the "Contact"
messages are received the pilot shall change to the nominated frequency
at the appropriate time and perform a check call on the frequency.

The sending or receipt of any of the "Contact" uplink messages is not an
indication to the pilot that CPDLC use must be terminated or suspended
once voice contact is established. If termination or suspension of CPDLC
use is intended by the controller when voice contact is established then
the requirement must be specifically stated in addition to the CONTACT
message element.[^21]

#### Synchronizing the CPDLC and voice transfer

If the CPDLC **[Monitor (or Contact) \[]{.smallcaps}icaounitname\]
\[frequency[\]]{.smallcaps}** message element and the **[End
Service]{.smallcaps}** message element are to be sent as separate uplink
messages, the **[End Service]{.smallcaps}** message should be sent as
soon as possible after the receipt of the **[Wilco]{.smallcaps}**
response. This is to ensure synchronization of the CPDLC and the voice
communication transfers.

#### Timing of the transfer of communications

The **[Monitor (or Contact)]{.smallcaps} \[icaounitname\]
\[frequency\]** and **[End Service]{.smallcaps}** message elements
should normally be sent after receipt of the last position report before
crossing the FIR boundary, but not less than 5 minutes prior to the FIR
boundary. This allows the next ATSU's connection to be active when the
aircraft crosses the FIR boundary.

#### Aircraft entering VHF coverage

For aircraft entering airspace where radar and air-ground VHF are
provided, and the aircraft will not cross an FIR boundary, it is not
necessary to send an **[End Service]{.smallcaps}** message to disconnect
CPDLC. In this case, the CPDLC connection will remain active until
termination of flight. If subsequent control sectors within the system
do not have CPDLC capability, and local instructions do not exist to the
contrary, the controller with jurisdiction for CPDLC must ensure that
CPDLC clearances or instructions are not issued to the aircraft while it
is under the control of another sector.

#### Timing of the CPDLC connection

Under normal circumstances the CPDLC connection should be established
with the next data authority prior to the connection between the
aircraft and the current data authority being terminated.

Either of the following options may be utilized to complete the CPDLC
connection transfer process:

a)  *Option 1* the **[Monitor (or Contact)]{.smallcaps} \[icaounitname\]
    \[frequency\]** and **[End Service]{.smallcaps}** message elements
    are sent in the same CPDLC uplink message.

Note. Because the CPDLC connection will be terminated when the pilot
sends the WILCO response, this multi element message should not be sent
more than 10 minutes from the frequency transfer point.[^22]

![](media/image8.wmf){width="3.638888888888889in"
height="1.8034722222222221in"}

Figure 8: CPDLC connection transfer - Option 1

b)  *Option 2:* the **[Monitor (or Contact)]{.smallcaps}
    \[icaounitname\] \[frequency\]** and the **[End
    Service]{.smallcaps}** message elements are sent as separate CPDLC
    uplink messages. The **[End Service]{.smallcaps}** is sent as soon
    as possible after the receipt of the **[Wilco]{.smallcaps}**
    response to the **[Monitor (or Contact)]{.smallcaps}** instruction.

![](media/image9.wmf){width="3.63125in" height="1.8020833333333333in"}

Figure 9: CPDLC connection transfer - Option 2

c)  *Option 3:* the AT \[position\](or AT \[time\]) [Monitor (or
    Contact)]{.smallcaps} \[icaounitname\] \[frequency\] and the [End
    Service]{.smallcaps} message elements are sent as separate CPDLC
    uplink messages. The [End Service]{.smallcaps} is sent after the
    receipt of the [Wilco]{.smallcaps} response to the [Monitor (or
    Contact)]{.smallcaps} instruction, and approaching the FIR boundary.

![](media/image10.wmf){width="3.6458333333333335in" height="1.8125in"}

[^23]

### Abnormal cases at the time of the connection / disconnection

#### Non-delivery of [End Service]{.smallcaps} message

There may be unusual situations where a CPDLC connection cannot be
automatically terminated (e.g. if the **[End Service]{.smallcaps}**
message does not trigger the disconnection, or if the **[End
Service]{.smallcaps}** message is not delivered to the

avionics). If the controller is aware that the **[End
Service]{.smallcaps}** message has been unsuccessful, the controller's
initial action should be to send another END SERVICE message. If this is
also unsuccessful the pilot will be instructed to terminate the CPDLC
connection and logon to the next unit.[^24]

The voice phraseology to be used will be:

  ---------------- ------------------------------------------------------------
  **Controller**   Select ATC Com Off then Logon to \[ATSU name\]

  **Pilot**        Roger
  ---------------- ------------------------------------------------------------

*The \[ATSU name\] is the four character ICAO code.*

#### Non-automatic termination of the connection

If the CPDLC connection with the current ATSU does not terminate
automatically at the appropriate time (i.e.

before the position or time notified in the CONTACT/MONITOR message),
then the pilot shall send the CPDLC report to the current active center.
If receipt of the position report does not prompt the current centre to
send an End Service message, then the pilot should manually disconnect
from the current ATSU and logon to the subsequent ATSU.[^25]

If the CPDLC transfer is intended to be delayed until after the aircraft
has passed the FIR transfer point, the controller shall notify the pilot
of the intended delay with the free text message EXPECT CPDLC TRANSFER
AT \[time\].

If the aircraft crosses the FIR boundary prior to the time notified in
the free text uplink, the boundary position will be sent to the ATSU
with the active connection.

If the CPDLC transfer has not been completed by the time notified in the
uplink message, the pilot is entitled to manually disconnect from the
active ATSU and logon to the subsequent ATSU.

# CPDLC Procedures

## Means of Communication

### General

Generally, when a CPDLC aircraft is operating within a CPDLC airspace
beyond the range of VHF voice communications, and other local rules do
not apply, then:

-   CPDLC will be the primary means of communication, and

-   Voice will be used as the backup communication medium (for example
    VHF, direct HF, third party HF, [Satvoice]{.smallcaps}).

The voice communication system should be capable of initiating emergency
messages.

### Voice communications

#### Notification of frequencies to the preceding ATSU

ATSUs shall advise frequencies to the preceding ATSU, in accordance with
the appropriate letters of agreement.

#### Notification of HF frequencies by CPDLC

The uplink CPDLC frequency transfer message elements can accommodate
only one frequency variable. Due to this limitation, the controller will
insert the primary HF frequency in these messages. This applies to the
following uplinks:

UL#117 CONTACT \[icaounitname\]\[frequency\]

UL#118 AT \[position\] CONTACT \[icaounitname\]\[frequency\]

UL#119 AT \[time\] CONTACT \[icaounitname\]\[frequency\]

UL#120 MONITOR \[icaounitname\]\[frequency\]

UL#121 AT \[position\] MONITOR \[icaounitname\]\[frequency\]

UL#122 AT \[time\] MONITOR \[icaounitname\]\[frequency\]

In areas of poor HF coverage, the controller may consider appending free
text nominating a secondary HF frequency. The format of this message is
described in Part 5.9. In the **[Contact]{.smallcaps}** and
**[Monitor]{.smallcaps}** messages RADIO is not an option within the
**\[icaounitname\]** field. Therefore CENTER will be used to identify a
RADIO facility.[^26]

## CPDLC Capability

### Notification of CPDLC capability

An AIP Supplement, or similar, shall be published to advise the CPDLC
capability of an ATS system and its AFN logon address. An aircraft's
CPDLC capability shall be notified in the flight plan.

### Downlink messages

ATS systems that allow the use of all elements contained in the FANS-1/A
message set should be capable of correctly processing all the FANS-1/A
downlink message elements. However, where specific CPDLC implementations
do not include all message set elements, such as domestic airspace or
initial and temporary situations, the ATSUs involved should publish the
reduced message set with appropriate explanatory material. Where these
reduced implementations occur across a group of adjoining ATSUs, every
attempt should be made to ensure that the message set chosen is common
to all applicable airspace within the implementation boundaries. ATSUs
should exercise caution when specifying reduced message sets, ensuring
that the messages handled are adequate for all envisaged scenarios in
the airspace to be served by CPDLC.

If the ground system receives a downlink message that is not supported
by the implemented message set, then the free text uplink message
(UL#169) MESSAGE NOT SUPPORTED BY THIS FACILITY should be sent rather
than terminating the connection.[^27]

### Uplink messages

For various reasons some States may not have implemented specific
FANS-1/A uplink message elements

contained in the message set in Section 5.8 (e.g. UL#33
**[Cruise]{.smallcaps}** **\[altitude\]**).[^28] These individual
implementations

shall not impact overall operations.

## Use of Pre-Formatted and Free Text Messages

### Preferred use of pre-formatted messages

Free text messages shall be used only when an appropriate pre-formatted
message element does not exist. In particular, the creation of a
clearance request and the issuing of a clearance shall be performed by
the use of pre-formatted message elements only. The use of pre-formatted
message elements allows on board data processing such as the automatic
insertion of the clearance information into the FMC. It also allows the
controller to respond more quickly when the ATS system has the
capability to automatically link a pre-formatted request to a
pre-formatted response. Additionally, this process minimizes the risk of
input errors.

When a free text message is required, standard ATC phraseology and
format shall be used. Non-essential words and phrases should be avoided.
Abbreviations should only be included in free text messages when they
form part of standard ICAO phraseology, e.g. ETA.

### Standardized free text messages

While pre-formatted message elements are required to be used whenever
possible, there are occasions where frequent use of freetext allows the
meaning and appropriate response to be standardized. The Standard Free
text message set is shown in Section 5.10.

### Storing free text messages

ATSUs capable of storing free text messages should select those message
elements from the standard free text message set (Section 5.10)
appropriate to their particular environments. When the storage of free
text messages is not possible, controllers shall use the same message
formats when typing free text messages.

## Exchange of CPDLC messages

### Message assurance

The FANS-1/A system does not provide for [end-to-end]{.underline}
message assurance. Therefore, there can be no guarantee provided by the
ground system or the avionics that the message has been delivered to the
controller or pilot. However:

-   The ATS system will receive a network acknowledgment (MAS Message
    Assurance) to an uplink message indicating that the message has been
    delivered to the aircraft's ACARS MU, and

-   The avionics will receive a network acknowledgment to a downlink
    message indicating that the message has been delivered to the
    communication service provider's system.

### Ambiguous dialogues

In the case of a controller or pilot having any doubt as to the intent
of a message, or if any other ambiguity exists, clarification shall be
sought through the use of voice communication.

### Interruption of a CPDLC dialogue

If a CPDLC dialogue is interrupted by a system shutdown, the entire
dialogue shall be re-commenced by voice communication.

### Approval of request or clearance / instruction

#### Affirmative response to a clearance/instruction 

The [**Wilco**]{.smallcaps} downlink message indicates that the pilot
will comply fully with the clearance/instruction contained in the
associated uplink message. The readback of a clearance or instruction
issued by CPDLC is not required.

#### Affirmative response to a clearance request

[T]{.smallcaps}he **[Roger]{.smallcaps}** or **[Affirm]{.smallcaps}**
uplinks are not appropriate responses to a clearance request and shall
not be used for this purpose. The controller shall only approve a
clearance request by uplinking a message containing an actual clearance.

#### Conditions relating to a specific clearance

Terms or conditions relating to a specific clearance shall be included
in the clearance uplink message. They shall not be sent as a separate
message.

#### Affirmative response to a negotiation request 

**[Affirm]{.smallcaps}** is an appropriate response to an uplinked
negotiation request message that is acceptable (e.**[g. Can You Accept
\[]{.smallcaps}altitude[\] At
\[]{.smallcaps}time[\]]{.smallcaps}**[)]{.smallcaps}.

### Negative response to a downlink request

#### Negative response to a clearance request

When a clearance request is denied, the controller shall use the element
**[Unable]{.smallcaps}** (not **[Negative]{.smallcaps}**) in the uplink
response.

#### Re-statement of a clearance

When a change to a clearance requested by the pilot is unable to be
accommodated by the controller, the request will be denied by the use of
the **[Unable]{.smallcaps}** response. The aircraft's current clearance
[shall not be]{.underline} re-stated.

#### Explanation of negative response

Pre-formatted elements such as **[Due to traffic]{.smallcaps}** (or a
free text element) should be added to the response message if
clarification is considered necessary. Additional elements (including
free text elements) in the form of an explanation must be included when
responding to a multiple clearance request where some, but not all
clearance requests can be granted.

#### Offering alternative clearances to downlink requests

If the clearance contained in a downlink request is not available, but
an alternative (similar) clearance is available, ATC must not simply
respond to the downlink request with the alternative uplink clearance.
An UNABLE must be uplinked to close the original clearance request.
Depending on workload and traffic, ATC may then uplink an alternative
clearance.

Example:

Pilot REQUEST CLIMB TO F370

Controller UNABLE. DUE TO TRAFFIC

CLIMB TO AND MAINTAIN F350. REPORT LEVEL F350

The ATC response in the following example is incorrect and should not be
used

Pilot REQUEST CLIMB TO F370

Controller ~~UNABLE. CLIMB TO AND MAINTAIN F350. REPORT LEVEL
F350~~[^29]

### Negative response to an uplink request

**[Negative]{.smallcaps}** is an appropriate response to an uplink
negotiation request that is not acceptable (e.g. **[Can you accept
\[]{.smallcaps}altitude[\] at
\[]{.smallcaps}time[\]]{.smallcaps}**[).]{.smallcaps}

### Time period between receiving and responding to a message

The controller and the pilot shall respond to incoming requests as soon
as practicable to avoid duplicate messages entering the system.

#### Delays in responding

The controller and the pilot should consider that it takes up to one
minute for a message to be received, time for the pilot (or the
controller) to take action and respond, and up to one minute for the
reply to be received. Nevertheless, they should be aware that extra
delays could occur in the transmission of any response to a CPDLC
message.

Note. Transmission times for messages may vary depending on the
transmission media.[^30]

#### Delay expected after receiving a "STANDBY" message

If the [**Standby**]{.smallcaps} response is received, a further
response can be expected within 10 minutes. The message remains open. If
the pilot (or the controller) does not respond within this time, the
next message should be in the form of an inquiry, not a duplicated
request.

### Re-sending Messages

#### Re-sending of a message when no alert received

When the pilot (or the controller) elects to re-send a message after a
reasonable period of time has passed and no error message has been
received indicating the non-delivery of the message, the message shall
be sent as a query message. Alternatively, voice communication may be
used.

Example:

  ----------- ------------------------------------------------------------
  **Pilot**   [Request climb]{.smallcaps} \[level[\]]{.smallcaps}

  ----------- ------------------------------------------------------------

  ----------- ------------------------------------------------------------
  **Pilot**   [When can I expect]{.smallcaps} \[level[\]]{.smallcaps}

  ----------- ------------------------------------------------------------

#### Re-sending of a message when an alert has been received

When an error message indicating the non-delivery of the message has
been received at the flight deck or at the controller work station, the
pilot (or the controller) may elect to re-send an identical message.
Alternatively, voice may be used.

### Duplicate requests received

#### Second identical request after an uplink "STANDBY" message

If a second identical downlink request is sent by the pilot after a
reasonable period (more than 10 minutes) has passed since receiving a
**[Standby]{.smallcaps}** response to an earlier request, the controller
should respond with [**Unable** **Request Deferred**]{.smallcaps}. This
will close out the second message, inform the pilot that the reply will
take longer, and will leave only one open message requiring a response.

#### Multiple identical requests 

All messages requiring a response must be answered. If the controller
(or the pilot) receives a second identical CPDLC request prior to having
answered the first, they shall respond to both of the messages to ensure
message closure. On rare occasions, the first uplink message may
generate an "invalid reference number" error message, in the avionics.

### Altitude change clearances

#### Issuing conditional altitude change clearances

The potential exists for the restriction "**[At]{.smallcaps}**"
contained at the beginning of the following conditional clearances to be
missed by aircrew and consequently the clearance may be executed
prematurely.

-   UL#21 **[At]{.smallcaps} \[time\] [Climb to and
    maintain]{.smallcaps} \[altitude\]**

-   UL#22 **[At]{.smallcaps} \[position\] [Climb to and
    maintain]{.smallcaps} \[altitude\]**

-   UL#24 **[At]{.smallcaps} \[time\] [Descend to and
    maintain]{.smallcaps} \[altitude\]**

-   UL#25 **[At]{.smallcaps} \[position\] [Descend to and
    maintain]{.smallcaps} \[altitude\]**

Controllers shall precede UL#21, UL#22, UL#24 and UL#25 with UL#19
**[Maintain]{.smallcaps}** **\[altitude\]** indicating to aircrew to
maintain their present altitude until the condition of the clearance is
satisfied.

#### Level report requirements for climb or descent clearances 

If a CPDLC level report [is required]{.underline}, controllers shall
append UL#129 **[Report level]{.smallcaps}** **\[altitude\]** to any
vertical change clearance to a single altitude so that flight crews have
access to the pre-formatted downlink report.

If no **[Report level]{.smallcaps}** **\[altitude\]** is received, the
crew has no requirement to report maintaining the cleared flight level.

*Example clearance issued to a flight currently cruising at FL310
requesting climb to FL350 when the climb can not be executed until the
aircraft is at 150W*

Maintain FL310, At MICKY Climb To and Maintain FL350, report level fl350

*Notes:*

1.  *Aircraft maintaining a level other than the level assigned has been
    identified as a significant problem in some regions. Using uplink
    message UL#129, REPORT LEVEL (altitude) is seen as one means of
    attempting to mitigate against such occurrences.*

2.  *Some States do not require this report in ADS airspace.*

[^31]

#### Canceling block altitude clearances

When a controller wishes to cancel a previously issued block clearance
and limit the aircraft to one specific level within the block; the
controller shall issue an appropriate vertical instruction such as:

-   UL#19 **[Maintain]{.smallcaps} \[altitude\];**

-   UL#20 **[Climb to and maintain]{.smallcaps} \[altitude\];** or

-   UL#28 **[Descend to reach]{.smallcaps} \[altitude\] [by]{.smallcaps}
    \[time\].**

The controller should also add UL#129 **[Report level]{.smallcaps}**
**\[altitude\]**.[^32]

The **[Wilco]{.smallcaps}** response to the vertical clearance uplink
cancels any previously issued block clearance.

### Requesting an aircraft's speed 

When the aircraft's Mach number or indicated airspeed is requested, the
controller shall use the pre-formatted message element **[Confirm
speed]{.smallcaps}**.

### Advising a wake turbulence offset

In the event of a pilot initiating a wake turbulence offset (up to 2nm
either side of track) in RVSM airspace for which the controller is not
required to issue a clearance, the pilot shall advise the controller.
The following data or voice phraseology shall be used:

+------------+---------------------------------------------------------+
| **Pilot**  | Wake Dev \[direction\]                                  |
|            |                                                         |
|            | *Direction L or R (left or right) as appropriate*       |
+------------+---------------------------------------------------------+

### Direct Tracking and UPR Aircraft

UPRs are calculated by airline flight planning systems as being the
optimal route clearance for the specific aircraft taking into account
the latest available weather information. As such, controllers should
not offer unsolicited direct tracking to aircraft flying a UPR as the
direct route may be less optimal than the aircraft's current route.[^33]

## Multi-Element Requests

### Avoiding multiple element clearance requests

To avoid potential ambiguity, pilots should, where possible, avoid
sending multiple clearance requests in the one downlink message.

### Responding to multiple element clearance requests

#### Multiple clearance requests in one message: All approved

Where a multiple clearance request [is]{.underline} received and all
clearance request elements can be approved, each clearance request
element shall be specifically addressed in the response.

Example

+---------+------------------------------------------------------------+
| **      | [Request climb to]{.smallcaps} \[level\]                   |
| Pilot** |                                                            |
|         | [Request direct to]{.smallcaps} \[position\]               |
+---------+------------------------------------------------------------+
| **Contr | [Climb to and maintain]{.smallcaps}                        |
| oller** | \[level[\]]{.smallcaps}                                    |
|         |                                                            |
|         | [Proceed direct to]{.smallcaps} \[position\]               |
+---------+------------------------------------------------------------+

#### Multiple clearance requests in one message: All not approved 

If the response to a multi-element message is **[Unable]{.smallcaps}**
then the reply applies to [all]{.underline} elements of the original
message.

Example

+---------+------------------------------------------------------------+
| **      | [Request climb to]{.smallcaps} \[level\]                   |
| Pilot** |                                                            |
|         | [Request direct to]{.smallcaps} \[position\]               |
+---------+------------------------------------------------------------+
| **Contr | [Unable]{.smallcaps}                                       |
| oller** |                                                            |
+---------+------------------------------------------------------------+

#### Multiple clearance requests in one message: Some approved / Some not approved

When a multi-element clearance request is received and part of it can be
granted and part of it cannot, the uplink [shall not]{.underline}
contain the single word **[Unable]{.smallcaps}** and a clearance. If
**[Unable]{.smallcaps}** is used within a clearance message, it must
contain a qualifier to remove any ambiguity.

The following examples illustrate **correct** ATC responses.

First correct example:

+---------+------------------------------------------------------------+
| **      | [Request climb to]{.smallcaps} \[level\]                   |
| Pilot** |                                                            |
|         | [Request direct to]{.smallcaps} \[position\]               |
+---------+------------------------------------------------------------+
| **Contr | [Unable]{.smallcaps}                                       |
| oller** |                                                            |
|         | Higher altitude                                            |
+---------+------------------------------------------------------------+

  ---------------- ------------------------------------------------------------
  **Controller**   [Proceed direct to]{.smallcaps} \[position\]

  ---------------- ------------------------------------------------------------

Second correct example:

+---------+------------------------------------------------------------+
| **      | [Request climb to]{.smallcaps} \[level\]                   |
| Pilot** |                                                            |
|         | [Request direct to]{.smallcaps} \[position\]               |
+---------+------------------------------------------------------------+
| **Contr | [Unable\                                                   |
| oller** | ]{.smallcaps}Higher altitude[\                             |
|         | Proceed direct to]{.smallcaps} \[position\]                |
+---------+------------------------------------------------------------+

The ATC response in the following example is **incorrect and shall never
be used**:

+---------+------------------------------------------------------------+
| **      | [Request climb to]{.smallcaps} \[level\]                   |
| Pilot** |                                                            |
|         | [Request direct to]{.smallcaps} \[position\]               |
+---------+------------------------------------------------------------+
| **Contr | [~~Unable~~]{.smallcaps}                                   |
| oller** |                                                            |
|         | ~~[Proceed direct to]{.smallcaps} \[position\]~~           |
+---------+------------------------------------------------------------+

## Multi-element Uplink Messages

### Combining multiple elements into a single message

Only uplink elements that are related to the overall message should be
combined into a single message. Messages that contain unrelated elements
could either cause confusion or result in the crew rejecting the entire
message when one of the elements on its own could have been acceptable.
The following multi-element uplink is an example of a clearance that can
be unambiguously sent as a single message.

WHEN READY

DESCEND TO AND MAINTAIN FL280

REPORT LEVEL FL280

When the elements are not dependent on each other, controllers should
send a single element clearance and wait for the response before sending
a subsequent instruction.

### Dependent Clearances

A dependent clearance is a message consisting of more than one clearance
element, where the pilot must comply with each of the elements. A
rejection of any of the elements, either singly or in combination,
renders the entire clearance invalid. The following multi-element uplink
is an example of a dependent clearance:

CLIMB TO AND MAINTAIN FL330

AT FL330 PROCEED DIRECT TO TUNTO

REPORT LEVEL FL330.

In this example the aircraft must complete a change of level in order to
be issued with an amended route clearance.

Whenever possible, all elements of a dependent clearance should be sent
in a single uplink message. Sending the elements as individual messages
may compromise safety or separation if the pilot accepts the first
uplink of a dependent clearance, complies with the instruction, and then
responds UNABLE to the next message when received. By the time that the
controller has received the UNABLE response, the aircraft could have
begun executing the first instruction of a clearance that is invalid if
the pilot cannot comply with the second element.

The response to a multi-element uplink message will either be a WILCO or
UNABLE that refers to the entire message. It is not possible for the
pilot to respond to individual elements of a multi-element message.

NOTE: Care must be taken in the construction of dependent clearances to
ensure that there is no ambiguity present in the message. In the example
above, the second element has been carefully chosen to reinforce the
requirement instead of using the word THEN followed by the route
clearance PROCEED DIRECT TO TUNTO.

The following message is an example of poor message construction as it
does not unambiguously convey to the pilot that the climb clearance must
be completed prior to commencing the route clearance component. This
format SHOULD NOT be used for dependent clearances:

~~CLIMB TO AND MAINTAIN FL330~~

~~THEN~~

~~PROCEED DIRECT TO TUNTO~~[^34]

## Message Closure

### General

Definitions:

-   A message requiring a response remains **open** until a referenced
    response is received.

```{=html}
<!-- -->
```
-   A message is **closed** when either a response is not technically
    required, or after a referenced response other than
    **[Standby]{.smallcaps}** or **[Request Deferred]{.smallcaps}** has
    been received.

A normal downlink free text message (based on downlink message element
DL#67) does not require a response from the controller to close the
CPDLC exchange. However, a downlink free text message based on downlink
message element DL#68 (Distress attribute) does require a response and
the message will remain open until a referenced response is received.

Any uplink message containing only free text requires a
**[Roger]{.smallcaps}** response. The message will remain open until a
referenced response containing [**Roger**]{.smallcaps} is received.

### Answering an uplink free text

When the controller sends a message containing only free text, or a free
text element combined with elements that do not require a response, the
pilot must respond to the free text with a [**Roger**]{.smallcaps}
response before responding to the actual contents of the message.

### Dialogue commenced via CPDLC and continued via voice

If a [CPDLC]{.smallcaps} message requiring a closure response is
subsequently negotiated by voice, a [CPDLC]{.smallcaps} closure response
message is still necessary to ensure the proper synchronization of
ground and aircraft systems.

## Position Reporting

### General

To harmonize waypoint position reports by either voice or data, the
"Position" and "Next Position" shall only contain compulsory reporting
points unless requested otherwise by ATC. The "Ensuing Significant
Point" may be either the compulsory or non-compulsory reporting point
after the "Next Position" (Refer AIREP form

PANS/ATM, Appendix 1). [^35]

### Downlink of position report

When a CPDLC connection exists in a procedural, non-ADS environment,
pilots shall ensure that position

reporting is conducted via CPDLC. A CPDLC position report shall be sent
manually by the pilot[^36] whenever an

ATC waypoint is passed over, (or passed abeam when offset flight is in
progress). ATC expects position reports based on downlink message
DL#48 - **[Position report]{.smallcaps}**.

### Flexible track position reports

All waypoints published for an independent flex track or user preferred
route (UPR) are compulsory reporting points. However, when the track
follows a published ATS route, position reports are not required at any
non-compulsory waypoints defined for that ATS route.[^37]

### First position report 

Pilots shall downlink a CPDLC position report (ATC waypoint) to the next
ATSU after the completion of:

-   An initial CPDLC connection (when inbound from an area not providing
    CPDLC services);

-   A CPDLC connection transfer; or

-   When crossing an FIR boundary.

### Sending of ATC waypoints only

Additional non-ATC waypoints may be sequenced by the FMC, however
information relating to these waypoints is not of interest to ATC. It is
the pilot's responsibility to report only at ATC waypoints.

### Updating a waypoint estimate

When it is necessary to update a waypoint ETA a free text message shall
be sent in the form of -- Revised [ETA]{.smallcaps} \[position\]
\[time[\].]{.smallcaps}

### Non-receipt of a scheduled position report

If a scheduled position report is not received via CPDLC, the use of
voice communication by the controller is not mandatory. The controller
may obtain the report by uplinking message UL#147 - **[Request position
report]{.smallcaps}**.

### Sequencing 'ABEAM' waypoints in excess of FMC parameters 

When an aircraft passes abeam a waypoint in excess of the defined
sequencing parameter for the aircraft type the FMC will not sequence the
active waypoint on the Legs and Position Report pages. Operators shall
develop appropriate airborne procedures to ensure correct waypoint
sequencing.

*Note: **Some** ATS systems use current GPS position that is included in
the ATC position report to update their ground systems.*

### ARINC 424 fix names

Crews should be aware that ATC ground systems can not process latitudes
and longitudes encoded as fix names in the ARINC 424 format. Example
10N40 (indicates lat/long of 10N140W).

Downlinks containing such fix names may be rejected by ATC systems.[^38]

## FANS-1/A CPDLC Message Set and Intent

This Appendix contains a complete listing of the message intent for all
FANS-1/A CPDLC messages as defined

by the OPLINK Panel. Additional comments provided by the ISPACG forum
are displayed in Italics.[^39]

### Response Requirements Key:

  ---------- ----------------------------------------------------------------
  **TYPE**   **CLOSURE RESPONSES**

  W/U        WILCO, UNABLE, will close the uplink message.

  A/N        AFFIRM, NEGATIVE, will close the uplink message.

  R          ROGER, will close the uplink message.

  NE         Most messages with an NE attribute require an operational
             response. Only the correct operational response is presented to
             the pilot. The uplink message is considered to be closed on
             sending and does not require a response to close the dialogue.
             The WILCO, UNABLE, AFFIRM, NEGATIVE, ROGER, and STANDBY
             responses are not enabled for pilot selection.

  Y          Response required.

  N          Response not required
  ---------- ----------------------------------------------------------------

*Note: Under some circumstances, an ERROR message will also close an
uplink message.*

Multi element uplink messages require only a single closure response.
The response required for a multi element message is the highest
priority response out of each of the elements in the message. When
determining the highest priority, the following priority order is used:

W/U

A/N

R

NE

For example, the uplink CLIMB TO AND MAINTAIN FL370. REPORT LEVEL FL370
contains two elements. The first element requires a "W/U" response, the
second an "R" response. The highest priority response is W/U, therefore
this is the response required for closure.[^40]

### Uplink - Responses and Acknowledgements

+---+--------------------------+------------------------------+--------+
| * | **[Message               | **[Message                   | **     |
| * | Element]{.smallcaps}**   | Intent]{.smallcaps}**        | [Respo |
| [ |                          |                              | nse]{. |
| U |                          |                              | smallc |
| L |                          |                              | aps}** |
| ] |                          |                              |        |
| { |                          |                              |        |
| . |                          |                              |        |
| s |                          |                              |        |
| m |                          |                              |        |
| a |                          |                              |        |
| l |                          |                              |        |
| l |                          |                              |        |
| c |                          |                              |        |
| a |                          |                              |        |
| p |                          |                              |        |
| s |                          |                              |        |
| } |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | UNABLE                   | Indicates that ATS cannot    | NE     |
| * |                          | comply with the request.     |        |
| 0 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | STANDBY                  | Indicates that ATS has       | NE     |
| * |                          | received the message and     |        |
| 1 |                          | will respond.                |        |
| * |                          |                              |        |
| * |                          | *The pilot is informed that  |        |
|   |                          | the request is being         |        |
|   |                          | assessed and there will be a |        |
|   |                          | [short-term                  |        |
|   |                          | delay]{.underline} (within   |        |
|   |                          | 10 minutes). The exchange is |        |
|   |                          | not closed and the request   |        |
|   |                          | will be responded to when    |        |
|   |                          | conditions allow.*           |        |
+---+--------------------------+------------------------------+--------+
| * | REQUEST DEFERRED         | Indicates that ATS has       | NE     |
| * |                          | received the request but it  |        |
| 2 |                          | has been deferred until      |        |
| * |                          | later.                       |        |
| * |                          |                              |        |
|   |                          | *The pilot is informed that  |        |
|   |                          | the request is being         |        |
|   |                          | assessed and a [long-term    |        |
|   |                          | delay]{.underline} can be    |        |
|   |                          | expected. The exchange is    |        |
|   |                          | not closed and the request   |        |
|   |                          | will be responded to when    |        |
|   |                          | conditions allow.*           |        |
+---+--------------------------+------------------------------+--------+
| * | ROGER                    | Indicates that ATS has       | NE     |
| * |                          | received and understood the  |        |
| 3 |                          | message.*.*                  |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | AFFIRM                   | Yes                          | NE     |
| * |                          |                              |        |
| 4 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | NEGATIVE                 | No                           | NE     |
| * |                          |                              |        |
| 5 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+

### Uplink - Vertical Clearances

+---+--------------------------+------------------------------+-------+
| * | **[Message               | **[Message                   | *     |
| * | Element]{.smallcaps}**   | Intent]{.smallcaps}**        | *[Res |
| [ |                          |                              | ponse |
| U |                          |                              | ]{.sm |
| L |                          |                              | allca |
| ] |                          |                              | ps}** |
| { |                          |                              |       |
| . |                          |                              |       |
| s |                          |                              |       |
| m |                          |                              |       |
| a |                          |                              |       |
| l |                          |                              |       |
| l |                          |                              |       |
| c |                          |                              |       |
| a |                          |                              |       |
| p |                          |                              |       |
| s |                          |                              |       |
| } |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | EXPECT \[altitude\]      | Notification that a level    | R     |
| * |                          | change instruction should be |       |
| 6 |                          | expected.                    |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | EXPECT CLIMB AT \[time\] | Notification that an         | R     |
| * |                          | instruction should be        |       |
| 7 |                          | expected for the aircraft to |       |
| * |                          | commence climb at the        |       |
| * |                          | specified time.              |       |
+---+--------------------------+------------------------------+-------+
| * | EXPECT CLIMB AT          | Notification that an         | R     |
| * | \[position\]             | instruction should be        |       |
| 8 |                          | expected for the aircraft to |       |
| * |                          | commence climb at the        |       |
| * |                          | specified position.          |       |
+---+--------------------------+------------------------------+-------+
| * | EXPECT DESCENT AT        | Notification that an         | R     |
| * | \[time\]                 | instruction should be        |       |
| 9 |                          | expected for the aircraft to |       |
| * |                          | commence descent at the      |       |
| * |                          | specified time.              |       |
+---+--------------------------+------------------------------+-------+
| * | EXPECT DESCENT AT        | Notification that an         | R     |
| * | \[position\]             | instruction should be        |       |
| 1 |                          | expected for the aircraft to |       |
| 0 |                          | commence descent at the      |       |
| * |                          | specified position.          |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | EXPECT CRUISE CLIMB AT   | Notification that an         | R     |
| * | \[time\]                 | instruction should be        |       |
| 1 |                          | expected for the aircraft to |       |
| 1 |                          | commence cruise climb at the |       |
| * |                          | specified time.              |       |
| * |                          |                              |       |
|   |                          | *Due to different            |       |
|   |                          | interpretations between the  |       |
|   |                          | various ATS units this       |       |
|   |                          | element should be avoided.*  |       |
+---+--------------------------+------------------------------+-------+
| * | EXPECT CRUISE CLIMB AT   | Notification that an         | R     |
| * | \[position\]             | instruction should be        |       |
| 1 |                          | expected for the aircraft to |       |
| 2 |                          | commence cruise climb at the |       |
| * |                          | specified position.          |       |
| * |                          |                              |       |
|   |                          | *Due to different            |       |
|   |                          | interpretations between the  |       |
|   |                          | various ATS units this       |       |
|   |                          | element should be avoided*   |       |
+---+--------------------------+------------------------------+-------+
| * | AT \[time\] EXPECT CLIMB | Notification that an         | R     |
| * | TO \[altitude\]          | instruction should be        |       |
| 1 |                          | expected for the aircraft to |       |
| 3 |                          | commence climb at the        |       |
| * |                          | specified time to the        |       |
| * |                          | specified level.             |       |
+---+--------------------------+------------------------------+-------+
| * | AT \[position\] EXPECT   | Notification that an         | R     |
| * | CLIMB TO \[altitude\]    | instruction should be        |       |
| 1 |                          | expected for the aircraft to |       |
| 4 |                          | commence climb at the        |       |
| * |                          | specified position to the    |       |
| * |                          | specified level.             |       |
+---+--------------------------+------------------------------+-------+
| * | AT \[time\] EXPECT       | Notification that an         | R     |
| * | DESCENT TO \[altitude\]  | instruction should be        |       |
| 1 |                          | expected for the aircraft to |       |
| 5 |                          | commence descent at the      |       |
| * |                          | specified time to the        |       |
| * |                          | specified level.             |       |
+---+--------------------------+------------------------------+-------+
| * | AT \[position\] EXPECT   | Notification that an         | R     |
| * | DESCENT TO \[altitude\]  | instruction should be        |       |
| 1 |                          | expected for the aircraft to |       |
| 6 |                          | commence descent at the      |       |
| * |                          | specified position to the    |       |
| * |                          | specified level.             |       |
+---+--------------------------+------------------------------+-------+
| * | AT \[time\] EXPECT       | Notification that an         | R     |
| * | CRUISE CLIMB TO          | instruction should be        |       |
| 1 | \[altitude\]             | expected for the aircraft to |       |
| 7 |                          | commence cruise climb at the |       |
| * |                          | specified time to the        |       |
| * |                          | specified level.             |       |
|   |                          |                              |       |
|   |                          | *Due to different            |       |
|   |                          | interpretations between the  |       |
|   |                          | various ATS units, this      |       |
|   |                          | element should be avoided.*  |       |
+---+--------------------------+------------------------------+-------+
| * | AT \[position\] EXPECT   | Notification that an         | R     |
| * | CRUISE CLIMB TO          | instruction should be        |       |
| 1 | \[altitude\]             | expected for the aircraft to |       |
| 8 |                          | commence cruise climb at the |       |
| * |                          | specified position to the    |       |
| * |                          | specified level.             |       |
|   |                          |                              |       |
|   |                          | *Due to different            |       |
|   |                          | interpretations between the  |       |
|   |                          | various ATS units, this      |       |
|   |                          | element should be avoided.*  |       |
+---+--------------------------+------------------------------+-------+
| * | MAINTAIN \[altitude\]    | Instruction to maintain the  | W/U   |
| * |                          | specified level.             |       |
| 1 |                          |                              |       |
| 9 |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | CLIMB TO AND MAINTAIN    | Instruction that a climb to  | W/U   |
| * | \[altitude\]             | the specified level is to    |       |
| 2 |                          | commence and the level is to |       |
| 0 |                          | be maintained when reached.  |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | AT \[time\] CLIMB TO AND | Instruction that at the      | W/U   |
| * | MAINTAIN \[altitude\]    | specified time, a climb to   |       |
| 2 |                          | the specified level is to    |       |
| 1 |                          | commence and once reached    |       |
| * |                          | the specified level is to be |       |
| * |                          | maintained.                  |       |
+---+--------------------------+------------------------------+-------+
| * | AT \[position\] CLIMB TO | Instruction that at the      | W/U   |
| * | AND MAINTAIN             | specified position, a climb  |       |
| 2 | \[altitude\]             | to the specified level is to |       |
| 2 |                          | commence and once reached    |       |
| * |                          | the specified level is to be |       |
| * |                          | maintained.                  |       |
+---+--------------------------+------------------------------+-------+
| * | DESCEND TO AND MAINTAIN  | Instruction that a descent   | W/U   |
| * | \[altitude\]             | to the specified level is to |       |
| 2 |                          | commence and the level is to |       |
| 3 |                          | be maintained when reached.  |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | AT \[time\] DESCEND TO   | Instruction that at the      | W/U   |
| * | AND MAINTAIN             | specified time a decent to   |       |
| 2 | \[altitude\]             | the specified level is to    |       |
| 4 |                          | commence and once reached    |       |
| * |                          | the specified level is to be |       |
| * |                          | maintained.                  |       |
+---+--------------------------+------------------------------+-------+
| * | AT \[position\] DESCEND  | Instruction that at the      | W/U   |
| * | TO AND MAINTAIN          | specified position a descent |       |
| 2 | \[altitude\]             | to the specified level is to |       |
| 5 |                          | commence and when the        |       |
| * |                          | specified level is reached   |       |
| * |                          | it is to be maintained.      |       |
+---+--------------------------+------------------------------+-------+
| * | CLIMB TO REACH           | Instruction that a climb is  | W/U   |
| * | \[altitude\] BY \[time\] | to commence at a rate such   |       |
| 2 |                          | that the specified level is  |       |
| 6 |                          | reached at or before the     |       |
| * |                          | specified time.              |       |
| * |                          |                              |       |
|   |                          | *When this element is        |       |
|   |                          | **not** combined with        |       |
|   |                          | another vertical clearance   |       |
|   |                          | the altitude specified is    |       |
|   |                          | the assigned level.*         |       |
+---+--------------------------+------------------------------+-------+
| * | CLIMB TO REACH           | Instruction that a climb is  | W/U   |
| * | \[altitude\] BY          | to commence at a rate such   |       |
| 2 | \[position\]             | that the specified level is  |       |
| 7 |                          | reached at or before the     |       |
| * |                          | specified position.          |       |
| * |                          |                              |       |
|   |                          | *When this element is        |       |
|   |                          | **not** combined with        |       |
|   |                          | another vertical clearance   |       |
|   |                          | the altitude specified is    |       |
|   |                          | the assigned level.*         |       |
+---+--------------------------+------------------------------+-------+
| * | DESCEND TO REACH         | Instruction that a descent   | W/U   |
| * | \[altitude\] BY \[time\] | is to commence at a rate     |       |
| 2 |                          | such that the specified      |       |
| 8 |                          | level is reached at or       |       |
| * |                          | before the specified time.   |       |
| * |                          |                              |       |
|   |                          | *When this element is        |       |
|   |                          | **not** combined with        |       |
|   |                          | another vertical clearance   |       |
|   |                          | the altitude specified is    |       |
|   |                          | the assigned level.*         |       |
+---+--------------------------+------------------------------+-------+
| * | DESCEND TO REACH         | Instruction that a descent   | W/U   |
| * | \[altitude\] BY          | is to commence at a rate     |       |
| 2 | \[position\]             | such that the specified      |       |
| 9 |                          | level is reached at or       |       |
| * |                          | before the specified         |       |
| * |                          | position.                    |       |
|   |                          |                              |       |
|   |                          | *When this element is        |       |
|   |                          | **not** combined with        |       |
|   |                          | another vertical clearance   |       |
|   |                          | the altitude specified is    |       |
|   |                          | the assigned level.*         |       |
+---+--------------------------+------------------------------+-------+
| * | MAINTAIN BLOCK           | A level within the specified | W/U   |
| * | \[altitude\] TO          | vertical range is to be      |       |
| 3 | \[altitude\]             | maintained.                  |       |
| 0 |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | CLIMB TO AND MAINTAIN    | Instruction that a climb to  | W/U   |
| * | BLOCK \[altitude\] TO    | a level within the specified |       |
| 3 | \[altitude\]             | vertical range is to         |       |
| 1 |                          | commence.                    |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | DESCEND TO AND MAINTAIN  | Instruction that a descent   | W/U   |
| * | BLOCK \[altitude\] TO    | to a level within the        |       |
| 3 | \[altitude\]             | specified vertical range is  |       |
| 2 |                          | to commence.                 |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | CRUISE \[altitude\]      | Instruction that authorizes  |       |
| * |                          | a pilot to conduct flight at |       |
| 3 |                          | any altitude from the        |       |
| 3 |                          | minimum altitude up to and   |       |
| * |                          | including the altitude       |       |
| * |                          | specified in the clearance.  |       |
|   |                          | further, it is approval for  |       |
|   |                          | the pilot to proceed to and  |       |
|   |                          | make an approach at the      |       |
|   |                          | destination airport.         |       |
|   |                          |                              |       |
|   |                          | *Due to different            |       |
|   |                          | interpretations between the  |       |
|   |                          | various ATS units, this      |       |
|   |                          | element should be avoided.*  |       |
+---+--------------------------+------------------------------+-------+
| * | CRUISE CLIMB TO          | A cruise climb is to         | W/U   |
| * | \[altitude\]             | commence and continue until  |       |
| 3 |                          | the specified level is       |       |
| 4 |                          | reached.                     |       |
| * |                          |                              |       |
| * |                          | *Due to different            |       |
|   |                          | interpretations between the  |       |
|   |                          | various ATS units, this      |       |
|   |                          | element should be avoided.*  |       |
+---+--------------------------+------------------------------+-------+
| * | CRUISE CLIMB ABOVE       | A cruise climb can commence  | W/U   |
| * | \[altitude\]             | once above the specified     |       |
| 3 |                          | level.                       |       |
| 5 |                          |                              |       |
| * |                          | *Due to different            |       |
| * |                          | interpretations between the  |       |
|   |                          | various ATS units, this      |       |
|   |                          | element should be avoided.*  |       |
+---+--------------------------+------------------------------+-------+
| * | EXPEDITE CLIMB TO        | The climb to the specified   | W/U   |
| * | \[altitude\]             | level should be made at the  |       |
| 3 |                          | aircraft\'s best rate.       |       |
| 6 |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | EXPEDITE DESCENT TO      | The descent to the specified | W/U   |
| * | \[altitude\]             | level should be made at the  |       |
| 3 |                          | aircraft\'s best rate.       |       |
| 7 |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | IMMEDIATELY CLIMB TO     | Urgent instruction to        | W/U   |
| * | \[altitude\]             | immediately climb to the     |       |
| 3 |                          | specified level.             |       |
| 8 |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | IMMEDIATELY DESCEND TO   | Urgent instruction to        | W/U   |
| * | \[altitude\]             | immediately descend to the   |       |
| 3 |                          | specified level.             |       |
| 9 |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | IMMEDIATELY STOP CLIMB   | Urgent instruction to        | W/U   |
| * | AT \[altitude\]          | immediately stop a climb     |       |
| 4 |                          | once the specified level is  |       |
| 0 |                          | reached.                     |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | IMMEDIATELY STOP DESCENT | Urgent instruction to        | W/U   |
| * | AT \[altitude\]          | immediately stop a descent   |       |
| 4 |                          | once the specified level is  |       |
| 1 |                          | reached.                     |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | CLIMB AT \[vertical      | Instruction to climb at not  | W/U   |
| * | rate\] MINIMUM           | less than the specified      |       |
| 1 |                          | rate.                        |       |
| 7 |                          |                              |       |
| 1 |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | CLIMB AT \[vertical      | Instruction to climb at not  | W/U   |
| * | rate\] MAXIMUM           | above the specified rate.    |       |
| 1 |                          |                              |       |
| 7 |                          |                              |       |
| 2 |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | DESCEND AT \[vertical    | Instruction to descend at    | W/U   |
| * | rate\] MINIMUM           | not less than the specified  |       |
| 1 |                          | rate.                        |       |
| 7 |                          |                              |       |
| 3 |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+
| * | DESCEND AT \[vertical    | Instruction to descend at    | W/U   |
| * | rate\] MAXIMUM           | not above the specified      |       |
| 1 |                          | rate.                        |       |
| 7 |                          |                              |       |
| 4 |                          |                              |       |
| * |                          |                              |       |
| * |                          |                              |       |
+---+--------------------------+------------------------------+-------+

### Uplink - Crossing Constraints

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[UL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **42**                 EXPECT TO CROSS            Notification that a level       R
                         \[position\] AT            change instruction should be    
                         \[altitude\]               expected which will require the 
                                                    specified position to be        
                                                    crossed at the specified level. 

  **43**                 EXPECT TO CROSS            Notification that a level       R
                         \[position\] AT OR ABOVE   change instruction should be    
                         \[altitude\]               expected which will require the 
                                                    specified position to be        
                                                    crossed at or above the         
                                                    specified level.                

  **44**                 EXPECT TO CROSS            Notification that a level       R
                         \[position\] AT OR BELOW   change instruction should be    
                         \[altitude\]               expected which will require the 
                                                    specified position to be        
                                                    crossed at or below the         
                                                    specified level.                

  **45**                 EXPECT TO CROSS            Notification that a level       R
                         \[position\] AT AND        change instruction should be    
                         MAINTAIN \[altitude\]      expected which will require the 
                                                    specified position to be        
                                                    crossed at the specified level  
                                                    which is to be maintained       
                                                    subsequently.                   

  **46**                 CROSS \[position\] AT      The specified position is to be W/U
                         \[altitude\]               crossed at the specified level. 
                                                    This may require the aircraft   
                                                    to modify its climb or descent  
                                                    profile.                        

  **47**                 CROSS \[position\] AT OR   The specified position is to be W/U
                         ABOVE \[altitude\]         crossed at or above the         
                                                    specified level.                

  **48**                 CROSS \[position\] AT OR   The specified position is to be W/U
                         BELOW \[altitude\]         crossed at or below the         
                                                    specified level.                

  **49**                 CROSS \[position\] AT AND  Instruction that the specified  W/U
                         MAINTAIN \[altitude\]      position is to be crossed at    
                                                    the specified level and that    
                                                    level is to be maintained when  
                                                    reached.                        

  **50**                 CROSS \[position\] BETWEEN The specified position is to be W/U
                         \[altitude\] AND           crossed at a level between the  
                         \[altitude\]               specified levels.               

  **51**                 CROSS \[position\] AT      The specified position is to be W/U
                         \[time\]                   crossed at the specified time.  

  **52**                 CROSS \[position\] AT OR   The specified position is to be W/U
                         BEFORE \[time\]            crossed at or before the        
                                                    specified time.                 

  **53**                 CROSS \[position\] AT OR   The specified position is to be W/U
                         AFTER \[time\]             crossed at or after the         
                                                    specified time.                 

  **54**                 CROSS \[position\] BETWEEN The specified position is to be W/U
                         \[time\] AND \[time\]      crossed at a time between the   
                                                    specified times.                

  **55**                 CROSS \[position\] AT      The specified position is to be W/U
                         \[speed\]                  crossed at the specified speed  
                                                    and the specified speed is to   
                                                    be maintained until further     
                                                    advised.                        

  **56**                 CROSS \[position\] AT OR   The specified position is to be W/U
                         LESS THAN \[speed\]        crossed at a speed equal to or  
                                                    less than the specified speed   
                                                    and the specified speed or less 
                                                    is to be maintained until       
                                                    further advised.                

  **57**                 CROSS \[position\] AT OR   The specified position is to be W/U
                         GREATER THAN \[speed\]     crossed at a speed equal to or  
                                                    greater than the specified      
                                                    speed and the specified speed   
                                                    or greater is to be maintained  
                                                    until further advised.          

  **58**                 CROSS \[position\] AT      The specified position is to be W/U
                         \[time\] AT \[altitude\]   crossed at the specified time   
                                                    and the specified level.        

  **59**                 CROSS \[position\] AT OR   The specified position is to be W/U
                         BEFORE \[time\] AT         crossed at or before the        
                         \[altitude\]               specified time and at the       
                                                    specified level.                

  **60**                 CROSS \[position\] AT OR   The specified position is to be W/U
                         AFTER \[time\] AT          crossed at or after the         
                         \[altitude\]               specified time and at the       
                                                    specified level.                

  **61**                 CROSS \[position\] AT AND  Instruction that the specified  W/U
                         MAINTAIN \[altitude\] AT   position is to be crossed at    
                         \[speed\]                  the specified level and speed   
                                                    and the level and speed are to  
                                                    be maintained.                  

  **62**                 AT \[time\] CROSS          Instruction that at the         W/U
                         \[position\] AT AND        specified time the specified    
                         MAINTAIN \[altitude\]      position is to be crossed at    
                                                    the specified level and the     
                                                    level is to be maintained.      

  **63**                 AT \[time\] CROSS          Instruction that at the         W/U
                         \[position\] AT AND        specified time the specified    
                         MAINTAIN \[altitude\] AT   position is to be crossed at    
                         \[speed\]                  the specified level and speed   
                                                    and the level and speed are to  
                                                    be maintained.                  
  ---------------------- -------------------------- ------------------------------- ----------------------------

### Uplink - Lateral Offsets

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[UL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **64**                 OFFSET \[direction\]       Instruction to fly a parallel   W/U
                         \[distance offset\] OF     track to the cleared route at a 
                         ROUTE                      displacement of the specified   
                                                    distance in the specified       
                                                    direction.                      

  **65**                 AT \[position\] OFFSET     Instruction to fly a parallel   W/U
                         \[direction\] \[distance   track to the cleared route at a 
                         offset\] OF ROUTE          displacement of the specified   
                                                    distance in the specified       
                                                    direction and commencing at the 
                                                    specified position.             

  **66**                 AT \[time\] OFFSET         Instruction to fly a parallel   W/U
                         \[direction\] \[distance   track to the cleared route at a 
                         offset\] OF ROUTE          displacement of the specified   
                                                    distance in the specified       
                                                    direction and commencing at the 
                                                    specified time.                 

  **67**                 PROCEED BACK ON ROUTE      The cleared flight route is to  W/U
                                                    be rejoined.                    

  **68**                 REJOIN ROUTE BY            The cleared flight route is to  W/U
                         \[position\]               be rejoined at or before the    
                                                    specified position.             

  **69**                 REJOIN ROUTE BY \[time\]   The cleared flight route is to  W/U
                                                    be rejoined at or before the    
                                                    specified time.                 

  **70**                 EXPECT BACK ON ROUTE BY    Notification that a clearance   R
                         \[position\]               may be issued to enable the     
                                                    aircraft to rejoin the cleared  
                                                    route at or before the          
                                                    specified position.             

  **71**                 EXPECT BACK ON ROUTE BY    Notification that a clearance   R
                         \[time\]                   may be issued to enable the     
                                                    aircraft to rejoin the cleared  
                                                    route at or before the          
                                                    specified time.                 
  ---------------------- -------------------------- ------------------------------- ----------------------------

  -------- -------------------------- ------------------------------- --------
  **72**   RESUME OWN NAVIGATION      Instruction to resume own       W/U
                                      navigation following a period   
                                      of tracking or heading          
                                      clearances. May be used in      
                                      conjunction with an instruction 
                                      on how or where to rejoin the   
                                      cleared route.                  

  -------- -------------------------- ------------------------------- --------

### Uplink - Route Modifications

  ---------------------- --------------------------- ------------------------------- ----------------------------
  **[UL]{.smallcaps}**   **[Message                  **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**      Intent]{.smallcaps}**           

  **73**                 \[predepartureclearance\]   Notification to the aircraft of W/U
                                                     the instructions to be followed 
                                                     from departure until the        
                                                     specified clearance limit.      

  **74**                 PROCEED DIRECT TO           Instruction to proceed directly W/U
                         \[position\]                from the present position to    
                                                     the specified position.         

  **75**                 WHEN ABLE PROCEED DIRECT TO Instruction to proceed, when    W/U
                         \[position\]                able, directly to the specified 
                                                     position.                       

  **76**                 AT \[time\] PROCEED DIRECT  Instruction to proceed, at the  W/U
                         TO \[position\]             specified time, directly to the 
                                                     specified position.             

  **77**                 AT \[position\] PROCEED     lnstruction to proceed, at the  W/U
                         DIRECT TO \[position\]      specified position, directly to 
                                                     the next specified position.    

  **78**                 AT \[altitude\] PROCEED     Instruction to proceed, upon    W/U
                         DIRECT TO \[position\]      reaching the specified level,   
                                                     directly to the specified       
                                                     position.                       

  **79**                 CLEARED TO \[position\] VIA Instruction to proceed to the   W/U
                         \[route clearance\]         specified position via the      
                                                     specified route.                

  **80**                 CLEARED \[route clearance\] Instruction to proceed via the  W/U
                                                     specified route.                

  **81**                 CLEARED \[procedure name\]  Instruction to proceed in       W/U
                                                     accordance with the specified   
                                                     procedure.                      

  **82**                 CLEARED TO DEVIATE UP TO    Approval to deviate up to the   W/U
                         \[direction\] \[distance    specified distance from the     
                         offset\] OF ROUTE           cleared route in the specified  
                                                     direction.                      

  **83**                 AT \[position\] CLEARED     Instruction to proceed from the W/U
                         \[route clearance\]         specified position via the      
                                                     specified route.                

  **84**                 AT \[position\] CLEARED     Instruction to proceed from the W/U
                         \[procedure name\]          specified position via the      
                                                     specified procedure.            

  **85**                 EXPECT \[route clearance\]  Notification that a clearance   R
                                                     to fly on the specified route   
                                                     may be issued.                  

  **86**                 AT \[position\] EXPECT      Notification that a clearance   R
                         \[route clearance\]         to fly on the specified route   
                                                     from the specified position may 
                                                     be issued.                      

  **87**                 EXPECT DIRECT TO            Notification that a clearance   R
                         \[position\]                to fly directly to the          
                                                     specified position may be       
                                                     issued.                         

  **88**                 AT \[position\] EXPECT      Notification that a clearance   R
                         DIRECT TO \[position\]      to fly directly from the first  
                                                     specified position to the next  
                                                     specified position may be       
                                                     issued.                         

  **89**                 AT \[time\] EXPECT DIRECT   Notification that a clearance   R
                         TO \[position\]             to fly directly to the          
                                                     specified position commencing   
                                                     at the specified time may be    
                                                     issued.                         

  **90**                 AT \[altitude\] EXPECT      Notification that a clearance   R
                         DIRECT TO \[position\]      to fly directly to the          
                                                     specified position commencing   
                                                     when the specified level is     
                                                     reached may be issued.          

  **91**                 HOLD AT \[position\]        Instruction to enter a holding  W/U
                         MAINTAIN \[altitude\]       pattern with the specified      
                         INBOUND TRACK               characteristics at the          
                         \[degrees\]\[direction\]    specified position and level.   
                         TURN LEG TIME \[leg type\]                                  

  **92**                 HOLD AT \[position\] AS     Instruction to enter a holding  W/U
                         PUBLISHED MAINTAIN          pattern with the published      
                         \[altitude\]                characteristics at the          
                                                     specified position and level.   

  **93**                 EXPECT FURTHER CLEARANCE AT Notification that an onwards    R
                         \[time\]                    clearance may be issued at the  
                                                     specified time.                 

  **94**                 TURN \[direction\] HEADING  Instruction to turn left or     W/U
                         \[degrees\]                 right as specified onto the     
                                                     specified heading.              

  **95**                 TURN \[direction\] GROUND   Instruction to turn left or     W/U
                         TRACK \[degrees\]           right as specified onto the     
                                                     specified track.                

  **96**                 FLY PRESENT HEADING         Instruction to continue to fly  W/U
                                                     on the current heading.         

  **97**                 AT \[position\] FLY HEADING Instruction to fly on the       W/U
                         \[degrees\]                 specified heading from the      
                                                     specified position.             

  **98**                 IMMEDIATELY TURN            Instruction to turn immediately W/U
                         \[direction\] HEADING       left or right as specified onto 
                         \[degrees\]                 the specified heading.          

  **99**                 EXPECT \[procedure name\]   Notification that a clearance   R
                                                     may be issued for the aircraft  
                                                     to fly the specified procedure. 

  **178**                TRACK DETAIL MESSAGE        *Message not defined.*          
  ---------------------- --------------------------- ------------------------------- ----------------------------

### Uplink - Speed Changes

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[UL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **100**                AT \[time\] EXPECT         Notification that a speed       R
                         \[speed\]                  instruction may be issued to be 
                                                    effective at the specified      
                                                    time.                           

  **101**                AT \[position\] EXPECT     Notification that a speed       R
                         \[speed\]                  instruction may be issued to be 
                                                    effective at the specified      
                                                    position.                       

  **102**                AT \[altitude\] EXPECT     Notification that a speed       R
                         \[speed\]                  instruction may be issued to be 
                                                    effective at the specified      
                                                    level.                          

  **103**                AT \[time\] EXPECT         Notification that a speed range R
                         \[speed\] TO \[speed\]     instruction may be issued to be 
                                                    effective at the specified      
                                                    time.                           

  **104**                AT \[position\] EXPECT     Notification that a speed range R
                         \[speed\] TO \[speed\]     instruction may be issued to be 
                                                    effective at the specified      
                                                    position.                       

  **105**                AT \[altitude\] EXPECT     Notification that a speed range R
                         \[speed\] TO \[speed\]     instruction may be issued to be 
                                                    effective at the specified      
                                                    level.                          

  **106**                MAINTAIN \[speed\]         The specified speed is to be    W/U
                                                    maintained.                     

  **107**                MAINTAIN PRESENT SPEED     The present speed is to be      W/U
                                                    maintained.                     

  **108**                MAINTAIN \[speed\] OR      The specified speed or a        W/U
                         GREATER                    greater speed is to be          
                                                    maintained.                     

  **109**                MAINTAIN \[speed\] OR LESS The specified speed or a lesser W/U
                                                    speed is to be maintained.      

  **110**                MAINTAIN \[speed\] TO      A speed within the specified    W/U
                         \[speed\]                  range is to be maintained.      

  **111**                INCREASE SPEED TO          The present speed is to be      W/U
                         \[speed\]                  increased to the specified      
                                                    speed and maintained until      
                                                    further advised.                

  **112**                INCREASE SPEED TO          The present speed is to be      W/U
                         \[speed\] OR GREATER       increased to the specified      
                                                    speed or greater, and           
                                                    maintained at or above the      
                                                    specified speed until further   
                                                    advised.                        

  **113**                REDUCE SPEED TO \[speed\]  The present speed is to be      W/U
                                                    reduced to the specified speed  
                                                    and maintained until further    
                                                    advised.                        
  ---------------------- -------------------------- ------------------------------- ----------------------------

  --------- -------------------------- ------------------------------- --------
  **114**   REDUCE SPEED TO \[speed\]  The present speed is to be      W/U
            OR LESS                    reduced to the specified speed  
                                       or less and maintained at or    
                                       below the specified speed until 
                                       further advised.                

  **115**   DO NOT EXCEED \[speed\]    The specified speed is not to   W/U
                                       be exceeded.                    

  **116**   RESUME NORMAL SPEED        Notification that the aircraft  W/U
                                       need no longer comply with the  
                                       previously issued speed         
                                       restriction.                    
  --------- -------------------------- ------------------------------- --------

### Uplink - Contact/Monitor/Surveillance Requests

+---+--------------------------+------------------------------+--------+
| * | **[Message               | **[Message                   | **     |
| * | Element]{.smallcaps}**   | Intent]{.smallcaps}**        | [Respo |
| [ |                          |                              | nse]{. |
| U |                          |                              | smallc |
| L |                          |                              | aps}** |
| ] |                          |                              |        |
| { |                          |                              |        |
| . |                          |                              |        |
| s |                          |                              |        |
| m |                          |                              |        |
| a |                          |                              |        |
| l |                          |                              |        |
| l |                          |                              |        |
| c |                          |                              |        |
| a |                          |                              |        |
| p |                          |                              |        |
| s |                          |                              |        |
| } |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONTACT                  | The pilot is required to     | W/U    |
| * | \[ica                    | call the ATS facility on the |        |
| 1 | ounitname\]\[frequency\] | specified frequency.         |        |
| 1 |                          |                              |        |
| 7 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | AT \[position\] CONTACT  | At the specified position    | W/U    |
| * | \[icaounitname\]         | the ATS unit with the        |        |
| 1 | \[frequency\]            | specified ATS unit name is   |        |
| 1 |                          | to be contacted on the       |        |
| 8 |                          | specified frequency.         |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | AT \[time\] CONTACT      | At the specified time the    | W/U    |
| * | \[icaounitname\]         | ATS unit with the specified  |        |
| 1 | \[frequency\]            | ATS unit name is to be       |        |
| 1 |                          | contacted on the specified   |        |
| 9 |                          | frequency.                   |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | MONITOR                  | The pilot is required to     | W/U    |
| * | \[ica                    | monitor the specified ATS    |        |
| 1 | ounitname\]\[frequency\] | facility on the specified    |        |
| 2 |                          | frequency. *The Pilot is not |        |
| 0 |                          | required to check in.*       |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | AT \[position\] MONITOR  | At the specified position    | W/U    |
| * | \[icaounitname\]         | the ATS unit with the        |        |
| 1 | \[frequency\]            | specified ATS unit name is   |        |
| 2 |                          | to be monitored on the       |        |
| 1 |                          | specified frequency.         |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | AT \[time\] MONITOR      | At the specified time the    | W/U    |
| * | \[icaounitname\]         | ATS unit with the specified  |        |
| 1 |                          | ATS unit name is to be       |        |
| 2 | \[frequency\]            | monitored on the specified   |        |
| 2 |                          | frequency.                   |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | SQUAWK \[beacon code\]   | The specified code (SSR      | W/U    |
| * |                          | code) is to be selected.     |        |
| 1 |                          |                              |        |
| 2 |                          |                              |        |
| 3 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | STOP SQUAWK              | The SSR transponder          | W/U    |
| * |                          | responses are to be          |        |
| 1 |                          | disabled.                    |        |
| 2 |                          |                              |        |
| 4 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | SQUAWK ALTITUDE          | The SSR transponder          | W/U    |
| * |                          | responses should include     |        |
| 1 |                          | level information.           |        |
| 2 |                          |                              |        |
| 5 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | STOP ALTITUDE SQUAWK     | The SSR transponder          | W/U    |
| * |                          | responses should no longer   |        |
| 1 |                          | include level information.   |        |
| 2 |                          |                              |        |
| 6 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | SQUAWK IDENT             | The \'ident\' function on    | W/U    |
| * |                          | the SSR transponder is to be |        |
| 1 |                          | actuated.                    |        |
| 7 |                          |                              |        |
| 9 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+

### Uplink - Report/Confirmation Requests

+---+--------------------------+------------------------------+--------+
| * | **[Message               | **[Message                   | **     |
| * | Element]{.smallcaps}**   | Intent]{.smallcaps}**        | [Respo |
| [ |                          |                              | nse]{. |
| U |                          |                              | smallc |
| L |                          |                              | aps}** |
| ] |                          |                              |        |
| { |                          |                              |        |
| . |                          |                              |        |
| s |                          |                              |        |
| m |                          |                              |        |
| a |                          |                              |        |
| l |                          |                              |        |
| l |                          |                              |        |
| c |                          |                              |        |
| a |                          |                              |        |
| p |                          |                              |        |
| s |                          |                              |        |
| } |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | REPORT BACK ON ROUTE     | Instruction to report when   | R      |
| * |                          | the aircraft is back on the  |        |
| 1 |                          | cleared route.               |        |
| 2 |                          |                              |        |
| 7 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | REPORT LEAVING           | Instruction to report when   | R      |
| * | \[altitude\]             | the aircraft has left the    |        |
| 1 |                          | specified level.             |        |
| 2 |                          |                              |        |
| 8 |                          | *Either a level that has     |        |
| * |                          | been maintained, or a level  |        |
| * |                          | passed through on climb or   |        |
|   |                          | descent.*                    |        |
+---+--------------------------+------------------------------+--------+
| * | REPORT LEVEL             | Instruction to report when   | R      |
| * | \[altitude\]             | the aircraft is in level     |        |
| 1 |                          | flight at the specified      |        |
| 2 |                          | level.                       |        |
| 9 |                          |                              |        |
| * |                          | *Some States do not to use   |        |
| * |                          | this message in order to     |        |
|   |                          | avoid confusion because it   |        |
|   |                          | does not comply with         |        |
|   |                          | existing voice phraseology*  |        |
+---+--------------------------+------------------------------+--------+

+---+--------------------------+------------------------------+--------+
| * | REPORT REACHING          | Instruction to report when   | R      |
| * | \[altitude\]             | the aircraft has reached the |        |
| 1 |                          | specified level.             |        |
| 7 |                          |                              |        |
| 5 |                          | *To be interpreted as        |        |
| * |                          | "Report reaching an assigned |        |
| * |                          | level."*                     |        |
+---+--------------------------+------------------------------+--------+
| * | REPORT REACHING BLOCK    | Instruction to report when   | R      |
| * | \[altitude\] TO          | the aircraft is within the   |        |
| 1 | \[altitude\]             | specified vertical range.    |        |
| 8 |                          |                              |        |
| 0 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | REPORT PASSING           | Instruction to report when   | R      |
| * | \[position\]             | the aircraft has passed the  |        |
| 1 |                          | specified position.          |        |
| 3 |                          |                              |        |
| 0 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | REPORT DISTANCE          | Instruction to report the    | NE     |
| * | \[to/from\] \[position\] | present distance to or from  |        |
| 1 |                          | the specified position.      |        |
| 8 |                          |                              |        |
| 1 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | REPORT REMAINING FUEL    | Instruction to report the    | NE     |
| * | AND SOULS ON BOARD       | amount of fuel remaining and |        |
| 1 |                          | the number of persons on     |        |
| 3 |                          | board.                       |        |
| 1 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM POSITION         | Instruction to report the    | NE     |
| * |                          | present position.            |        |
| 1 |                          |                              |        |
| 3 |                          |                              |        |
| 2 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM ALTITUDE         | Instruction to report the    | NE     |
| * |                          | present level.               |        |
| 1 |                          |                              |        |
| 3 |                          |                              |        |
| 3 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM SPEED            | Instruction to report the    | NE     |
| * |                          | present speed.               |        |
| 1 |                          |                              |        |
| 3 |                          |                              |        |
| 4 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM ASSIGNED         | Instruction to confirm and   | NE     |
| * | ALTITUDE                 | acknowledge the currently    |        |
| 1 |                          | assigned level.              |        |
| 3 |                          |                              |        |
| 5 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM ASSIGNED SPEED   | Instruction to confirm and   | NE     |
| * |                          | acknowledge the currently    |        |
| 1 |                          | assigned speed.              |        |
| 3 |                          |                              |        |
| 6 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM ASSIGNED ROUTE   | Instruction to confirm and   | NE     |
| * |                          | acknowledge the currently    |        |
| 1 |                          | assigned route.              |        |
| 3 |                          |                              |        |
| 7 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM TIME OVER        | Instruction to confirm the   | NE     |
| * | REPORTED WAYPOINT        | previously reported time     |        |
| 1 |                          | over the last reported       |        |
| 3 |                          | waypoint.                    |        |
| 8 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM REPORTED         | Instruction to confirm the   | NE     |
| * | WAYPOINT                 | identity of the previously   |        |
| 1 |                          | reported waypoint.           |        |
| 3 |                          |                              |        |
| 9 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM NEXT WAYPOINT    | lnstruction to confirm the   | NE     |
| * |                          | identity of the next         |        |
| 1 |                          | waypoint.                    |        |
| 4 |                          |                              |        |
| 0 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM NEXT WAYPOINT    | Instruction to confirm the   | NE     |
| * | ETA                      | previously reported          |        |
| 1 |                          | estimated time at the next   |        |
| 4 |                          | waypoint.                    |        |
| 1 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM ENSUING WAYPOINT | Instruction to confirm the   | NE     |
| * |                          | identity of the next plus    |        |
| 1 |                          | one waypoint.                |        |
| 4 |                          |                              |        |
| 2 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM REQUEST          | The request was not          | NE     |
| * |                          | understood. It should be     |        |
| 1 |                          | clarified and resubmitted.   |        |
| 4 |                          |                              |        |
| 3 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM SQUAWK           | Instruction to report the    | NE     |
| * |                          | currently selected           |        |
| 1 |                          | transponder code.            |        |
| 4 |                          |                              |        |
| 4 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM HEADING          | Instruction to report the    | NE     |
| * |                          | present heading.             |        |
| 1 |                          |                              |        |
| 4 |                          |                              |        |
| 5 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM GROUND TRACK     | Instruction to report the    | NE     |
| * |                          | present ground track.        |        |
| 1 |                          |                              |        |
| 4 |                          |                              |        |
| 6 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CONFIRM ATIS CODE        | Instruction to report the    | NE     |
| * |                          | identification code of the   |        |
| 1 |                          | last ATIS received.          |        |
| 8 |                          |                              |        |
| 2 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | REQUEST POSITION REPORT  | Instruction to make a        | NE     |
| * |                          | position report.             |        |
| 1 |                          |                              |        |
| 4 |                          | *To be used if the           |        |
| 7 |                          | controller does not receive  |        |
| * |                          | a scheduled position         |        |
| * |                          | report.*                     |        |
+---+--------------------------+------------------------------+--------+

### Uplink - Negotiation Requests

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[UL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **148**                WHEN CAN YOU ACCEPT        Request for the earliest time   NE
                         \[altitude\]               at which the specified level    
                                                    can be accepted.                

  **149**                CAN YOU ACCEPT             Instruction to report whether   A/N
                         \[altitude\] AT            or not the specified level can  
                         \[position\]               be accepted at the specified    
                                                    position.                       

  **150**                CAN YOU ACCEPT             Instruction to report whether   A/N
                         \[altitude\] AT \[time\]   or not the specified level can  
                                                    be accepted at the specified    
                                                    time.                           

  **151**                WHEN CAN YOU ACCEPT        Instruction to report the       NE
                         \[speed\]                  earliest time when the          
                                                    specified speed can be          
                                                    accepted.                       

  **152**                WHEN CAN YOU ACCEPT        Instruction to report the       NE
                         \[direction\] \[distance   earliest time when the          
                         offset\] OFFSET            specified offset track can be   
                                                    accepted.                       
  ---------------------- -------------------------- ------------------------------- ----------------------------

### Uplink - Air Traffic Advisories

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[UL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **153**                ALTIMETER \[altimeter\]    ATS advisory that the altimeter R
                                                    setting should be the specified 
                                                    setting.                        

  **154**                RADAR SERVICES TERMINATED  ATS advisory that the radar     R
                                                    service is terminated.          

  **155**                RADAR CONTACT \[position\] ATS advisory that radar contact R
                                                    has been established at the     
                                                    specified position.             

  **156**                RADAR CONTACT LOST         ATS advisory that radar contact R
                                                    has been lost.                  

  **157**                CHECK STUCK MICROPHONE     A continuous transmission is    R
                         \[frequency\]              detected on the specified       
                                                    frequency. Check the microphone 
                                                    button.                         

  **158**                ATIS \[atis code\]         ATS advisory that the ATIS      R
                                                    information identified by the   
                                                    specified code is the current   
                                                    ATIS information.               
  ---------------------- -------------------------- ------------------------------- ----------------------------

### Uplink - System Management Messages

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[UL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **159**                ERROR \[error              A system generated message that NE
                         information\]              the ground system has detected  
                                                    an error.                       

  **160**                NEXT DATA AUTHORITY        Notification to the avionics    NE
                         \[facility designation\]   that the next data authority is 
                                                    the specified ATSU.             

  **161**                END SERVICE                Notification to the avionics    NE
                                                    that the data link connection   
                                                    with the current data authority 
                                                    is being terminated.            

  **162**                SERVICE UNAVAILABLE        Notification that the ground    NE
                                                    system does not support this    
                                                    message.                        

  **163**                \[icao facility            Notification to the pilot of an NE
                         designation\] \[tp4Table\] ATSU identifier.                
  ---------------------- -------------------------- ------------------------------- ----------------------------

### Uplink - Additional Messages

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[UL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **164**                WHEN READY                 The associated instruction may  NE
                                                    be complied with at any future  
                                                    time.                           

  **165**                THEN                       Used to link two messages,      NE
                                                    indicating the proper order of  
                                                    execution of clearances/        
                                                    instructions.                   

  **166**                DUE TO TRAFFIC             The associated instruction is   NE
                                                    issued due to traffic           
                                                    considerations.                 

  **167**                DUE TO AIRSPACE            The associated instruction is   NE
                         RESTRICTION                issued due to airspace          
                                                    restrictions.                   
  ---------------------- -------------------------- ------------------------------- ----------------------------

+---+--------------------------+------------------------------+--------+
| * | DISREGARD                | The indicated communication  | R      |
| * |                          | should be ignored.           |        |
| 1 |                          |                              |        |
| 6 |                          | *The previously sent uplink  |        |
| 8 |                          | CPDLC message shall be       |        |
| * |                          | ignored. DISREGARD should    |        |
| * |                          | not refer to a clearance or  |        |
|   |                          | instruction. If DISREGARD is |        |
|   |                          | used, another element shall  |        |
|   |                          | be added to clarify which    |        |
|   |                          | message is to be             |        |
|   |                          | disregarded.*                |        |
+---+--------------------------+------------------------------+--------+
| * | MAINTAIN OWN SEPARATION  | Notification that the pilot  | W/U    |
| * | AND VMC                  | is responsible for           |        |
| 1 |                          | maintaining separation from  |        |
| 7 |                          | other traffic and is also    |        |
| 6 |                          | responsible for maintaining  |        |
| * |                          | Visual Meteorological        |        |
| * |                          | Conditions.                  |        |
+---+--------------------------+------------------------------+--------+
| * | AT PILOTS DISCRETION     | Used in conjunction with a   | N      |
| * |                          | clearance or instruction to  |        |
| 1 |                          | indicate that the pilot may  |        |
| 7 |                          | execute when prepared to do  |        |
| 7 |                          | so.                          |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | \[free text\]            | *Normal urgency attribute*   | R      |
| * |                          |                              |        |
| 1 |                          |                              |        |
| 6 |                          |                              |        |
| 9 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | \[free text\]            | *Distress urgency attribute* | R      |
| * |                          |                              |        |
| 1 |                          |                              |        |
| 7 |                          |                              |        |
| 0 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+

### Downlink - Responses

+---+--------------------------+------------------------------+--------+
| * | **[Message               | **[Message                   | **     |
| * | Element]{.smallcaps}**   | Intent]{.smallcaps}**        | [Respo |
| [ |                          |                              | nse]{. |
| D |                          |                              | smallc |
| L |                          |                              | aps}** |
| ] |                          |                              |        |
| { |                          |                              |        |
| . |                          |                              |        |
| s |                          |                              |        |
| m |                          |                              |        |
| a |                          |                              |        |
| l |                          |                              |        |
| l |                          |                              |        |
| c |                          |                              |        |
| a |                          |                              |        |
| p |                          |                              |        |
| s |                          |                              |        |
| } |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | WILCO                    | The instruction is           | N      |
| * |                          | understood and will be       |        |
| 0 |                          | complied with.               |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | UNABLE                   | The instruction cannot be    | N      |
| * |                          | complied with.               |        |
| 1 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | STANDBY                  | Wait for a reply.            | N      |
| * |                          |                              |        |
| 2 |                          | *The controller is informed  |        |
| * |                          | that the request is being    |        |
| * |                          | assessed and there will be a |        |
|   |                          | [short term]{.underline}     |        |
|   |                          | delay (within 10 minutes).   |        |
|   |                          | The exchange is not closed   |        |
|   |                          | and the request will be      |        |
|   |                          | responded to when conditions |        |
|   |                          | allow.*                      |        |
+---+--------------------------+------------------------------+--------+
| * | ROGER                    | Message received and         | N      |
| * |                          | understood.                  |        |
| 3 |                          |                              |        |
| * |                          | *R[OGER]{.smallcaps} is the  |        |
| * |                          | only correct response to an  |        |
|   |                          | uplink free text message.    |        |
|   |                          | Under no circumstances will  |        |
|   |                          | ROGER be used instead of     |        |
|   |                          | AFFIRM.*                     |        |
+---+--------------------------+------------------------------+--------+
| * | AFFIRM                   | Yes                          | [N]    |
| * |                          |                              | {.smal |
| 4 |                          | *[Affirm]{.smallcaps} is an  | lcaps} |
| * |                          | appropriate response to an   |        |
| * |                          | uplinked negotiation request |        |
|   |                          | message (e.g. [Can you       |        |
|   |                          | accept                       |        |
|   |                          | \[]{.smallcaps}altitude[\]   |        |
|   |                          | at \[]{.smallcaps}time\]).*  |        |
+---+--------------------------+------------------------------+--------+
| * | NEGATIVE                 | No                           | [N]    |
| * |                          |                              | {.smal |
| 5 |                          | *[Negative]{.smallcaps} is   | lcaps} |
| * |                          | an appropriate response to   |        |
| * |                          | an uplinked negotiation      |        |
|   |                          | request message (e.g. [Can   |        |
|   |                          | you accept                   |        |
|   |                          | \[]{.smallcaps}altitude[\]   |        |
|   |                          | at                           |        |
|   |                          | \[]{.small                   |        |
|   |                          | caps}time[\])]{.smallcaps}.* |        |
+---+--------------------------+------------------------------+--------+

### Downlink - Vertical Requests

+---+--------------------------+------------------------------+--------+
| * | **[Message               | **[Message                   | **     |
| * | Element]{.smallcaps}**   | Intent]{.smallcaps}**        | [Respo |
| [ |                          |                              | nse]{. |
| D |                          |                              | smallc |
| L |                          |                              | aps}** |
| ] |                          |                              |        |
| { |                          |                              |        |
| . |                          |                              |        |
| s |                          |                              |        |
| m |                          |                              |        |
| a |                          |                              |        |
| l |                          |                              |        |
| l |                          |                              |        |
| c |                          |                              |        |
| a |                          |                              |        |
| p |                          |                              |        |
| s |                          |                              |        |
| } |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | REQUEST \[altitude\]     | Request to fly at the        | Y      |
| * |                          | specified level.             |        |
| 6 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | REQUEST BLOCK            | Request to fly at a level    | Y      |
| * | \[altitude\] TO          | within the specified         |        |
| 7 | \[altitude\]             | vertical range.              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | REQUEST CRUISE CLIMB TO  | Request to cruise climb to   | Y      |
| * | \[altitude\]             | the specified level.         |        |
| 8 |                          |                              |        |
| * |                          | *Due to different            |        |
| * |                          | interpretations between the  |        |
|   |                          | various ATS units, this      |        |
|   |                          | element should be avoided.*  |        |
+---+--------------------------+------------------------------+--------+
| * | REQUEST CLIMB TO         | Request to climb to the      | Y      |
| * | \[altitude\]             | specified level.             |        |
| 9 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | REQUEST DESCENT TO       | Request to descend to the    | Y      |
| * | \[altitude\]             | specified level.             |        |
| 1 |                          |                              |        |
| 0 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | AT \[position\] REQUEST  | Request that at the          | Y      |
| * | CLIMB TO \[altitude\]    | specified position a climb   |        |
| 1 |                          | to the specified level be    |        |
| 1 |                          | approved.                    |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | AT \[position\] REQUEST  | Request that at the          | Y      |
| * | DESCENT TO \[altitude\]  | specified position a descent |        |
| 1 |                          | to the specified level be    |        |
| 2 |                          | approved.                    |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | AT \[time\] REQUEST      | Request that at the          | Y      |
| * | CLIMB TO \[altitude\]    | specified time a climb to    |        |
| 1 |                          | the specified level be       |        |
| 3 |                          | approved.                    |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | AT \[time\] REQUEST      | Request that at the          | Y      |
| * | DESCENT TO \[altitude\]  | specified time a descent to  |        |
| 1 |                          | the specified level be       |        |
| 4 |                          | approved.                    |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+

### Downlink - Lateral Off-Set Requests

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[DL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **15**                 REQUEST OFFSET             Request that a parallel track,  Y
                         \[direction\] \[distance   offset from the cleared track   
                         offset\] OF ROUTE          by the specified distance in    
                                                    the specified direction, be     
                                                    approved.                       

  **16**                 AT \[position\] REQUEST    Request that a parallel track,  Y
                         OFFSET \[direction\]       offset from the cleared track   
                         \[distance offset\] OF     by the specified distance in    
                         ROUTE                      the specified direction, be     
                                                    approved from the specified     
                                                    position.                       

  **17**                 AT \[time\] REQUEST OFFSET Request that a parallel track,  Y
                         \[direction\] \[distance   offset from the cleared track   
                         offset\] OF ROUTE          by the specified distance in    
                                                    the specified direction, be     
                                                    approved from the specified     
                                                    time.                           
  ---------------------- -------------------------- ------------------------------- ----------------------------

### Downlink - Speed Requests

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[DL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **18**                 REQUEST \[speed\]          Request to fly at the specified Y
                                                    speed.                          

  **19**                 REQUEST \[speed\] TO       Request to fly within the       Y
                         \[speed\]                  specified speed range.          
  ---------------------- -------------------------- ------------------------------- ----------------------------

### Downlink - Voice Contact Requests

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[DL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **20**                 REQUEST VOICE CONTACT      Request for voice contact.      Y

  **21**                 REQUEST VOICE CONTACT      Request for voice contact on    Y
                         \[frequency\]              the specified frequency.        
  ---------------------- -------------------------- ------------------------------- ----------------------------

### Downlink - Route Modification Requests

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[DL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **22**                 REQUEST DIRECT TO          Request to track from the       Y
                         \[position\]               present position direct to the  
                                                    specified position.             

  **23**                 REQUEST \[procedure name\] Request for the specified       Y
                                                    procedure clearance.            

  **24**                 REQUEST \[route            Request for a route clearance.  Y
                         clearance\]                                                

  **25**                 REQUEST CLEARANCE          Request for either a            Y
                                                    pre-departure or route          
                                                    clearance.                      

  **26**                 REQUEST WEATHER DEVIATION  Request for a weather deviation Y
                         TO \[position\] VIA        to the specified position via   
                         \[route clearance\]        the specified route.            

  **27**                 REQUEST WEATHER DEVIATION  Request for a weather deviation Y
                         UP TO \[direction\]        up to the specified distance    
                         \[distance offset\] OF     off track in the specified      
                         ROUTE                      direction.                      

  **70**                 REQUEST HEADING            Request a clearance to adopt    Y
                         \[degrees\]                the specified heading.          

  **71**                 REQUEST GROUND TRACK       Request a clearance to adopt    Y
                         \[degrees\]                the specified ground track.     
  ---------------------- -------------------------- ------------------------------- ----------------------------

### Downlink - Reports

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[DL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **28**                 LEAVING \[altitude\]       Notification of leaving the     N
                                                    specified level.                

  **29**                 CLIMBING TO \[altitude\]   Notification of climbing to the N
                                                    specified level.                

  **30**                 DESCENDING TO \[altitude\] Notification of descending to   N
                                                    the specified level.            

  **31**                 PASSING \[position\]       Notification of passing the     N
                                                    specified position.             

  **78**                 AT \[time\] \[distance\]   At the specified time, the      N
                         \[to/from\] \[position\]   aircraft\'s position was as     
                                                    specified.                      

  **32**                 PRESENT ALTITUDE           Notification of the present     N
                         \[altitude\]               level.                          

  **33**                 PRESENT POSITION           Notification of the present     N
                         \[position\]               position.                       

  **34**                 PRESENT SPEED \[speed\]    Notification of the present     N
                                                    speed.                          

  **35**                 PRESENT HEADING            Notification of the present     N
                         \[degrees\]                heading in degrees.             

  **36**                 PRESENT GROUND TRACK       Notification of the present     N
                         \[degrees\]                ground track in degrees.        

  **37**                 LEVEL \[altitude\]         Notification that the aircraft  N
                                                    is maintaining the specified    
                                                    level.                          

  **72**                 REACHING \[altitude\]      Notification that the aircraft  N
                                                    has reached the specified       
                                                    level.                          

  **76**                 REACHING BLOCK             Notification that the aircraft  N
                         \[altitude\] TO            has reached a level within the  
                         \[altitude\]               specified vertical range.       

  **38**                 ASSIGNED ALTITUDE          Read-back of the assigned       N
                         \[altitude\]               level.                          

  **77**                 ASSIGNED BLOCK             Read-back of the assigned       N
                         \[altitude\] TO            vertical range.                 
                         \[altitude\]                                               

  **39**                 ASSIGNED SPEED \[speed\]   Read-back of the assigned       N
                                                    speed.                          

  **40**                 ASSIGNED ROUTE \[route     Read-back of the assigned       N
                         clearance\]                route.                          

  **41**                 BACK ON ROUTE              The aircraft has regained the   N
                                                    cleared route.                  

  **42**                 NEXT WAYPOINT \[position\] The next waypoint is the        N
                                                    specified position.             

  **43**                 NEXT WAYPOINT ETA \[time\] The ETA at the next waypoint is N
                                                    as specified.                   

  **44**                 ENSUING WAYPOINT           The next plus one waypoint is   N
                         \[position\]               the specified position.         

  **45**                 REPORTED WAYPOINT          Clarification of previously     N
                         \[position\]               reported waypoint passage.      

  **46**                 REPORTED WAYPOINT \[time\] Clarification of time over      N
                                                    previously reported waypoint.   

  **47**                 SQUAWKING \[beacon code\]  The specified (SSR) code has    N
                                                    been selected.                  
  ---------------------- -------------------------- ------------------------------- ----------------------------

+---+--------------------------+------------------------------+--------+
| * | POSITION REPORT          | Reports the current position | N      |
| * | \[position report\]      | of the aircraft when the     |        |
| 4 |                          | pilot presses the button to  |        |
| 8 |                          | send this message.           |        |
| * |                          |                              |        |
| * |                          | *ATC expects position        |        |
|   |                          | reports based on this        |        |
|   |                          | downlink message*            |        |
+---+--------------------------+------------------------------+--------+
| * | ATIS \[atis code\]       | The code of the latest ATIS  | N      |
| * |                          | received is as specified.    |        |
| 7 |                          |                              |        |
| 9 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | DEVIATING \[direction\]  | Notification that the        | N      |
| * | \[distance offset\] OF   | aircraft is deviating from   |        |
| 8 | ROUTE                    | the cleared route by the     |        |
| 0 |                          | specified distance in the    |        |
| * |                          | specified direction.         |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+

### Downlink - Negotiation Requests

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[DL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **49**                 WHEN CAN WE EXPECT         Request for the earliest time   Y
                         \[speed\]                  at which a clearance to the     
                                                    specified speed can be          
                                                    expected.                       

  **50**                 WHEN CAN WE EXPECT         Request for the earliest time   Y
                         \[speed\] TO \[speed\]     at which a clearance to a speed 
                                                    within the specified range can  
                                                    be expected.                    

  **51**                 WHEN CAN WE EXPECT BACK ON Request for the earliest time   Y
                         ROUTE                      at which a clearance to regain  
                                                    the planned route can be        
                                                    expected.                       

  **52**                 WHEN CAN WE EXPECT LOWER   Request for the earliest time   Y
                         ALTITUDE                   at which a clearance to descend 
                                                    can be expected.                

  **53**                 WHEN CAN WE EXPECT HIGHER  Request for the earliest time   Y
                         ALTITUDE                   at which a clearance to climb   
                                                    can be expected.                

  **54**                 WHEN CAN WE EXPECT CRUISE  Request for the earliest time   Y
                         CLIMB TO \[altitude\]      at which a clearance to cruise  
                                                    climb to the specified level    
                                                    can be expected.                
  ---------------------- -------------------------- ------------------------------- ----------------------------

### Downlink - Emergency Messages

+---+--------------------------+------------------------------+--------+
| * | **[Message               | **[Message                   | **     |
| * | Element]{.smallcaps}**   | Intent]{.smallcaps}**        | [Respo |
| [ |                          |                              | nse]{. |
| D |                          |                              | smallc |
| L |                          |                              | aps}** |
| ] |                          |                              |        |
| { |                          |                              |        |
| . |                          |                              |        |
| s |                          |                              |        |
| m |                          |                              |        |
| a |                          |                              |        |
| l |                          |                              |        |
| l |                          |                              |        |
| c |                          |                              |        |
| a |                          |                              |        |
| p |                          |                              |        |
| s |                          |                              |        |
| } |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | PAN PAN PAN              | Urgency prefix.              | N      |
| * |                          |                              |        |
| 5 |                          |                              |        |
| 5 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | MAYDAY MAYDAY MAYDAY     | Distress prefix.             | N      |
| * |                          |                              |        |
| 5 |                          |                              |        |
| 6 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | \[remaining fuel\] OF    | Notification of fuel         | N      |
| * | FUEL REMAINING AND       | remaining and number of      |        |
| 5 | \[souls on board\] SOULS | persons on board.            |        |
| 7 | ON BOARD                 |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | CANCEL EMERGENCY         | Notification that the pilot  | N      |
| * |                          | wishes to cancel the         |        |
| 5 |                          | emergency condition.         |        |
| 8 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | DIVERTING TO             | Notification that the        | N      |
| * | \[position\] or          | aircraft is diverting to the |        |
| 5 |                          | specified position via the   |        |
| 9 | DIVERTING TO             | specified route.             |        |
| * | \[position\] VIA \[x\]   |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+
| * | OFFSETTING \[direction\] | Notification that the        | N      |
| * | \[distance offset\] OF   | aircraft is deviating the    |        |
| 6 | ROUTE                    | specified distance in the    |        |
| 0 |                          | specified direction off the  |        |
| * |                          | cleared route and            |        |
| * |                          | maintaining a parallel       |        |
|   |                          | track.                       |        |
+---+--------------------------+------------------------------+--------+
| * | DESCENDING TO            | Notification that the        | N      |
| * | \[altitude\]             | aircraft is descending to    |        |
| 6 |                          | the specified level.         |        |
| 1 |                          |                              |        |
| * |                          |                              |        |
| * |                          |                              |        |
+---+--------------------------+------------------------------+--------+

### Downlink -System Management Messages

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[DL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **62**                 ERROR \[error              A system generated message that N
                         information\]              the avionics has detected an    
                                                    error.                          
  ---------------------- -------------------------- ------------------------------- ----------------------------

  -------- -------------------------- ------------------------------- --------
  **63**   NOT CURRENT DATA AUTHORITY A system generated denial to    N
                                      any CPDLC message sent from a   
                                      ground facility that is not the 
                                      Current Data Authority.         

  **64**   \[icao facility            Notification to the ground      N
           designation\]              system that the specified ATSU  
                                      is the current data authority.  

  **73**   \[version number\]         A system generated message      N
                                      indicating the software version 
                                      number.                         
  -------- -------------------------- ------------------------------- --------

### Downlink -Additional Messages

  ---------------------- -------------------------- ------------------------------- ----------------------------
  **[DL]{.smallcaps}**   **[Message                 **[Message                      **[Response]{.smallcaps}**
                         Element]{.smallcaps}**     Intent]{.smallcaps}**           

  **65**                 DUE TO WEATHER             Used to explain reasons for     N
                                                    aircraft operator's message.    

  **66**                 DUE TO AIRCRAFT            Used to explain reasons for     N
                         PERFORMANCE                aircraft operator\'s message.   

  **74**                 MAINTAIN OWN SEPARATION    States a desire by the pilot to N
                         AND VMC                    provide his/her own separation  
                                                    and remain in VMC.              

  **75**                 AT PILOTS DISCRETION       Used in conjunction with        N
                                                    another message to indicate     
                                                    that the pilot wishes to        
                                                    execute the request when the    
                                                    pilot is prepared to do so.     

  **67**                 \[free text\]              *Normal urgency attribute*      N

  **67b**                WE CAN ACCEPT \[altitude\] We can accept the specified     N
                         AT \[time\]                level at the specified time.    

  **67c**                WE CAN ACCEPT \[speed\] AT We can accept the specified     N
                         \[time\]                   speed at the specified time.    

  **67d**                WE CAN ACCEPT              We can accept a parallel track  N
                         \[direction\] \[distance   offset the specified distance   
                         offset\] AT \[time\]       in the specified direction at   
                                                    the specified time.             

  **67e**                WE CANNOT ACCEPT           We cannot accept the specified  N
                         \[altitude\]               level.                          

  **67f**                WE CANNOT ACCEPT \[speed\] We cannot accept the specified  N
                                                    speed.                          

  **67g**                WE CANNOT ACCEPT           We cannot accept a parallel     N
                         \[direction\] \[distance   track offset the specified      
                         offset\]                   distance in the specified       
                                                    direction.                      

  **67h**                WHEN CAN WE EXPECT CLIMB   Request for the earliest time   N
                         TO \[altitude\]            at which a clearance to climb   
                                                    to the specified level can be   
                                                    expected.                       

  **67i**                WHEN CAN WE EXPECT DESCENT Request for the earliest time   N
                         TO \[altitude\]            at which a clearance to descend 
                                                    to the specified level can be   
                                                    expected.                       

  **68**                 \[free text\]              *Distress urgency attribute*    Y
  ---------------------- -------------------------- ------------------------------- ----------------------------

## FANS-1/A CPDLC Standard Free Text Messages

This Appendix contains a complete listing of the standard free text
messages and intent for FANS-1/A CPDLC.

When a free text uplink message has been received, the pilot shall
respond with the [Quick Response]{.smallcaps} from the table before
responding to the message.

### Uplink - Free Text Report/ Confirmation Requests

+-----------+---------------------------------------------+------------+
|           | **[Free Text Message]{.smallcaps}**         | **[Quick   |
|           |                                             | Res        |
|           |                                             | ponse]{.sm |
|           |                                             | allcaps}** |
+-----------+---------------------------------------------+------------+
| **Con     | REPORT SIGHTING AND PASSING OPPOSITE        |            |
| troller** | DIRECTION \[traffic description\] ETP       |            |
|           | \[time\]                                    |            |
|           |                                             |            |
|           | *The traffic description is to be inserted  |            |
|           | by the controller and shall include the     |            |
|           | aircraft identification (callsign), flight  |            |
|           | level and aircraft type. ETP = Estimated    |            |
|           | Time of Passing.*                           |            |
|           |                                             |            |
|           | *Example of the traffic description: SIA228 |            |
|           | B747 FL370*                                 |            |
+-----------+---------------------------------------------+------------+
| **Pilot   | \[traffic identification\] SIGHTED AND      | **ROGER**  |
| R         | PASSED                                      |            |
| esponse** |                                             |            |
|           | *Example - SIA228 SIGHTED AND PASSED*       |            |
|           |                                             |            |
|           | **or**                                      |            |
|           |                                             |            |
|           | \[traffic identification\] NOT SIGHTED      |            |
+-----------+---------------------------------------------+------------+
| **Message | The controller is requesting that the pilot |            |
| Intent**  | notify when the specified traffic has been  |            |
|           | seen by visual contact and passed. The      |            |
|           | level specified in the traffic description  |            |
|           | is the level being maintained by the        |            |
|           | opposite direction aircraft.                |            |
+-----------+---------------------------------------------+------------+

+-----------+---------------------------------------------+------------+
|           | **[Free Text Message]{.smallcaps}**         | **[Quick   |
|           |                                             | Res        |
|           |                                             | ponse]{.sm |
|           |                                             | allcaps}** |
+-----------+---------------------------------------------+------------+
| **Con     | REPORT GROUND SPEED                         |            |
| troller** |                                             |            |
+-----------+---------------------------------------------+------------+
| **Pilot   | GS \[speed\]                                | **ROGER**  |
| R         |                                             |            |
| esponse** | *Example - GS 490*                          |            |
+-----------+---------------------------------------------+------------+
| **Message | The controller is requesting that the pilot |            |
| Intent**  | report the present ground speed.            |            |
+-----------+---------------------------------------------+------------+

+-----------+---------------------------------------------+------------+
|           | **[Free Text Message]{.smallcaps}**         | **[Quick   |
|           |                                             | Res        |
|           |                                             | ponse]{.sm |
|           |                                             | allcaps}** |
+-----------+---------------------------------------------+------------+
| **Con     | STATE PREFERRED LEVEL                       |            |
| troller** |                                             |            |
|           | (Ref: ICAO UM231)                           |            |
+-----------+---------------------------------------------+------------+
| **Pilot   | FL \[altitude\]                             | **ROGER**  |
| R         |                                             |            |
| esponse** | *Example - FL 350*                          |            |
+-----------+---------------------------------------------+------------+
| **Message | The controller is requesting that the pilot |            |
| Intent**  | advise the preferred flight level for the   |            |
|           | flight.                                     |            |
+-----------+---------------------------------------------+------------+

[^41]

+-----------+---------------------------------------------+------------+
|           | **[Free Text Message]{.smallcaps}**         | **[Quick   |
|           |                                             | Res        |
|           |                                             | ponse]{.sm |
|           |                                             | allcaps}** |
+-----------+---------------------------------------------+------------+
| **Con     | REPORT ETA \[position\]                     |            |
| troller** |                                             |            |
|           | *Example - REQUEST ESTIMATE BILBO*          |            |
|           |                                             |            |
|           | (Ref: ICAO UM228)                           |            |
+-----------+---------------------------------------------+------------+
| **Pilot   | \[position\] \[time\]                       | **ROGER**  |
| R         |                                             |            |
| esponse** | *Example - BILBO 0413*                      |            |
+-----------+---------------------------------------------+------------+
| **Message | The controller is requesting an estimate    |            |
| Intent**  | for the specified waypoint.                 |            |
+-----------+---------------------------------------------+------------+

[^42]

+-----------+---------------------------------------------+------------+
|           | **[Free Text Message]{.smallcaps}**         | **[Quick   |
|           |                                             | Res        |
|           |                                             | ponse]{.sm |
|           |                                             | allcaps}** |
+-----------+---------------------------------------------+------------+
| **Con     | WHEN WILL YOU MAINTAIN FL \[altitude\]      |            |
| troller** |                                             |            |
+-----------+---------------------------------------------+------------+
| **Pilot   | FL \[altitude\] AT \[time\]                 | **ROGER**  |
| R         |                                             |            |
| esponse** | *Example - FL 350 AT 2317*                  |            |
+-----------+---------------------------------------------+------------+
| **Message | The controller is requesting from the pilot |            |
| Intent**  | the time at which the aircraft will         |            |
|           | maintain the specified level.               |            |
+-----------+---------------------------------------------+------------+

+-----------+---------------------------------------------+------------+
|           | **[Free Text Message]{.smallcaps}**         | **[Quick   |
|           |                                             | Res        |
|           |                                             | ponse]{.sm |
|           |                                             | allcaps}** |
+-----------+---------------------------------------------+------------+
| **Con     | AT WHAT DISTANCE \[position / waypoint\]    |            |
| troller** | WILL YOU MAINTAIN FL \[altitude\]           |            |
+-----------+---------------------------------------------+------------+
| **Pilot   | FL \[altitude\] AT \[distance\] NM          | **ROGER**  |
| R         | \[direction\] \[position / waypoint\]       |            |
| esponse** |                                             |            |
|           | *Example - FL 350 AT 26 NM W IPEMA*         |            |
+-----------+---------------------------------------------+------------+
| **Message | The controller is requesting the distance   |            |
| Intent**  | from the specified position or waypoint at  |            |
|           | which the aircraft will maintain the        |            |
|           | specified level. The pilot shall include    |            |
|           | the direction from the waypoint as a        |            |
|           | cardinal point, e.g. N, NE, NW, S, SW, SE,  |            |
|           | E or W.                                     |            |
+-----------+---------------------------------------------+------------+

+-----------+---------------------------------------------+------------+
|           | **[Free Text Message]{.smallcaps}**         | **[Quick   |
|           |                                             | Res        |
|           |                                             | ponse]{.sm |
|           |                                             | allcaps}** |
+-----------+---------------------------------------------+------------+
| **Con     | REPORT RADIAL AND DISTANCE \[to/from\]      |            |
| troller** | \[position\]                                |            |
+-----------+---------------------------------------------+------------+
| **Pilot   | \[radial\] R \[distance\] NM \[to/from\]    | **ROGER**  |
| R         | \[position\]                                |            |
| esponse** |                                             |            |
|           | *Example - 320 R 26 NM FROM MCY*            |            |
+-----------+---------------------------------------------+------------+
| **Message | The controller is requesting that the pilot |            |
| Intent**  | report the radial on which the aircraft is  |            |
|           | proceeding and the distance from the        |            |
|           | specified VOR.                              |            |
+-----------+---------------------------------------------+------------+

  ---------------- --------------------------------------------- -------------------------
                   **[Free Text Message]{.smallcaps}**           **[Quick
                                                                 Response]{.smallcaps}**

  **Controller**   REQUEST VOICE CONTACT \[frequency\]           

  **Pilot                                                        **ROGER**
  Response**                                                     

  **Message        The controller is requesting that the pilot   
  Intent**         makes voice contact / radio check call on the 
                   specified frequency.                          
  ---------------- --------------------------------------------- -------------------------

### Uplink - Free Text Instructions

  ---------------- --------------------------------------------- -------------------------
                   **[Free Text Message]{.smallcaps}**           **[Quick
                                                                 Response]{.smallcaps}**

  **Controller**   CHECK ATC LOG PAGE FOR OPEN MESSAGES          

  **Pilot                                                        **ROGER**
  Response**                                                     

  **Message        The controller has detected that uplink       
  Intent**         messages exist that the pilot has not yet     
                   responded to. The pilot is required to check  
                   the ATC log page and to respond to unanswered 
                   uplink messages.                              
  ---------------- --------------------------------------------- -------------------------

### Uplink - Freetext Advisories

  ---------------- --------------------------------------------- -------------------------
                   **[Free Text Message]{.smallcaps}**           **[Quick
                                                                 Response]{.smallcaps}**

  **Controller**   EXPECT SELCAL CHECK HF \[frequency\]          

  **Pilot                                                        **ROGER**
  Response**                                                     

  **Message        The controller is notifying the pilot that a  
  Intent**         selcal check will be made on the specified HF 
                   frequency.                                    
  ---------------- --------------------------------------------- -------------------------

  ---------------- --------------------------------------------- -------------------------
                   **[Free Text Message]{.smallcaps}**           **[Quick
                                                                 Response]{.smallcaps}**

  **Controller**   EXPECT CPDLC TRANSFER AT \[time\]             

  **Pilot                                                        **ROGER**
  Response**                                                     

  **Message        The controller is notifying the pilot that    
  Intent**         the CPDLC transfer process will not be        
                   completed at the FIR boundary and will be     
                   delayed until the specified time. If the      
                   CPDLC transfer is not completed by the        
                   specified time, the pilot shall manually      
                   disconnect and logon to the next centre.      
  ---------------- --------------------------------------------- -------------------------

  ---------------- --------------------------------------------- -------------------------
                   **[Free Text Message]{.smallcaps}**           **[Quick
                                                                 Response]{.smallcaps}**

  **Controller**   EXPECT NEXT CENTER \[ATSU name\]. CONTACT     
                   WITH \[ATSU name\] NOT REQUIRED               

  **Pilot                                                        **ROGER**
  Response**                                                     

  **Message        The controller is notifying the pilot that    
  Intent**         CPDLC connection is not required by the next  
                   FIR (where the flight\'s transition time of   
                   that FIR is short) and CPDLC connection will  
                   be transferred to the subsequent FIR.         
  ---------------- --------------------------------------------- -------------------------

*The \[ATSU name\] is the relevant four character ICAO code.*

  ---------------- --------------------------------------------- -------------------------
                   **[Free Text Message]{.smallcaps}**           **[Quick
                                                                 Response]{.smallcaps}**

  **Controller**   TRAFFIC IS \[traffic description\]            

  **Pilot          (optional) TRAFFIC SIGHTED                    **ROGER**
  Response**                                                     

  **Message        The controller is notifying the pilot of      
  Intent**         traffic significant to the flight. The        
                   description will include the aircraft type    
                   and any other relevant information to assist  
                   the pilot in sighting the traffic. The pilot  
                   may respond that the traffic has been         
                   sighted.                                      
  ---------------- --------------------------------------------- -------------------------

  ---------------- --------------------------------------------- -------------------------
                   **[Free Text Message]{.smallcaps}**           **[Quick
                                                                 Response]{.smallcaps}**

  **Controller**   SECONDARY HF \[frequency\]                    

  **Pilot                                                        **ROGER**
  Response**                                                     

  **Message        The controller is notifying the pilot of the  
  Intent**         secondary HF frequency for the area.          
  ---------------- --------------------------------------------- -------------------------

### Uplink - Free Text Speed Messages

  ---------------- --------------------------------------------- -------------------------
                   **[Free Text Message]{.smallcaps}**           **[Quick
                                                                 Response]{.smallcaps}**

  **Controller**   EXPECT TO MAINTAIN \[speed\] UNTIL \[time /   
                   position\]                                    

  **Pilot                                                        **ROGER**
  Response**                                                     

  **Message        The controller is notifying the pilot that a  
  Intent**         speed instruction may be issued to be         
                   effective until the specified time.           
  ---------------- --------------------------------------------- -------------------------

### Uplink - Free Text Emergency Acknowledgment

  ---------------- --------------------------------------------- -------------------------
                   **[Free Text Message]{.smallcaps}**           **[Quick
                                                                 Response]{.smallcaps}**

  **Controller**   ROGER MAYDAY                                  

  **Pilot                                                        **ROGER**
  Response**                                                     

  **Message        The controller has acknowledged receipt of a  
  Intent**         MAYDAY downlink message. The controller shall 
                   attempt to make voice contact with the pilot. 
                   The pilot should only respond with ROGER if   
                   or when able to do so. If the aircraft is     
                   inbound to an airport within the FIR, a ROGER 
                   response is not required.                     
  ---------------- --------------------------------------------- -------------------------

  ---------------- --------------------------------------------- -------------------------
                   **[Free Text Message]{.smallcaps}**           **[Quick
                                                                 Response]{.smallcaps}**

  **Controller**   ROGER PAN                                     

  **Pilot                                                        **ROGER**
  Response**                                                     

  **Message        The controller has acknowledged receipt of a  
  Intent**         PAN downlink message. The controller shall    
                   attempt to make voice contact with the pilot. 
                   The pilot should only respond with ROGER if   
                   or when able to do so. If the aircraft is     
                   inbound to an airport within the FIR, a ROGER 
                   response is not required.                     
  ---------------- --------------------------------------------- -------------------------

### Downlink - Free Text Advisories

+----------------+---------------------------------------+------------+
|                | **[Free Text Message]{.smallcaps}**   | **[Res     |
|                |                                       | ponse]{.sm |
|                |                                       | allcaps}** |
+----------------+---------------------------------------+------------+
| **Pilot**      | [Wake Dev]{.smallcaps} \[direction\]  |            |
|                |                                       |            |
|                | *Direction L or R (left or right) as  |            |
|                | appropriate*                          |            |
+----------------+---------------------------------------+------------+
| **Controller   |                                       | **ROGER**  |
| Response**     |                                       |            |
+----------------+---------------------------------------+------------+
| **Message      | The pilot is offsetting due wake      |            |
| Intent**       | turbulence in accordance with RVSM    |            |
|                | procedures (offset will not exceed    |            |
|                | 2nm). The controller is not required  |            |
|                | to respond or issue a clearance.      |            |
+----------------+---------------------------------------+------------+

  ----------------- ---------------------------------------- ----------------------------
                    **[Free Text Message]{.smallcaps}**      **[Response]{.smallcaps}**

  **Pilot**         [Revised ETA]{.smallcaps} \[position\]   
                    \[time[\]]{.smallcaps}                   

  **Controller                                               **ROGER**
  Response**                                                 

  **Message         The pilot is advising ATC of an update a 
  Intent**          waypoint ETA.                            
  ----------------- ---------------------------------------- ----------------------------

# ADS Procedures

## Introduction

In the CNS/ATM environment, surveillance may be provided by Automatic
Dependent Surveillance (ADS).[^43]

ADS allows the establishment of communication contracts between ground
systems and an aircraft\'s avionics

system. An ADS contract contains the ATC data requirements for ADS
reporting as well as[^44] frequency of the

ADS reports.

The implementation of ADS provides surveillance capability in oceanic
and en-route continental airspace and is intended to replace CPDLC and
verbal position reporting in areas where non-radar separation is
currently applied.

In non-radar airspace, the effective use of ADS in the provision of air
traffic services enhances flight safety, facilitates the reduction of
separation minima and better accommodates user-preferred flight
profiles.

## ADS Description

Three types of ADS contracts can be established with an aircraft. Each
of these contracts operates independently from the others. These
contracts are the:

-   Periodic;

-   Event; and

-   Demand.

The establishment of ADS contracts is initiated by the ground system and
does not require pilot action providing that the airborne system is
armed. The pilot has the ability to cancel all contracts by selecting
ADS off.

### The periodic contract 

The periodic contract allows an ATSU to specify the reporting frequency,
to request that optional data groups be added to the basic ADS report,
and to specify the frequency at which the optional groups are to be
included in the reports.

The periodic reporting rate can generally be altered by the controller
to allow for situations such as a reduced separation standard[^45] where
a higher reporting rate may be required. Only one periodic contract can
be

established between a ground system and a particular aircraft at any one
time. Whenever a new periodic contract is established, the previous
periodic contract is replaced. The periodic contract will remain in
effect until it is modified or cancelled.

### The event contract

An event contract specifies a request for reports to be transmitted by
the aircraft whenever a defined "event" occurs. Only one event contract
can be established between a ground system and a particular aircraft at
any one time, however the event contract can contain multiple event
types.

Note that multiple ATSUs with ADS connections can each establish their
own event contracts with an aircraft.[^46]

Once an event contract has been established, it remains in effect until
the specific event requests are fulfilled, or it is cancelled by the
ground system.

The **Vertical Rate Change Event** is triggered when the aircraft's
vertical rate is either less than or greater than a parameter defined in
the contract.

The **Lateral Deviation Change Event** is triggered when the aircraft's
actual position exceeds a lateral distance parameter from the aircraft's
expected position on the active flight plan.

The **Altitude Range Change Event** is triggered when the aircraft's
altitude exceeds the altitude ceiling or floor defined in the contract
by the ground system.

Once a vertical rate change, lateral deviation change, or altitude range
event trigger has occurred, a recurrence of this event no longer
triggers an event report. The ground system must initiate a new event
contract every time that one of these specific events occurs.

The **Waypoint Change Event** is triggered by a change to the next or
the next-plus-one waypoints. Such a

change normally occurs due to routine waypoint sequencing. However, it
will also be triggered by occurrences such as a change to a non-ATS
waypoint entered by the pilot for operational reasons, or execution of a
new route affecting the next or next-plus-one waypoints.[^47] Unlike the
other event contracts, the waypoint change event

trigger remains in effect for all waypoint changes.

### The demand contract

The demand contract is a "one-off" request from the ground system for
the FMS to provide an ADS report containing specific data as defined in
the request. A demand contract can be requested by the ground system at
any time. The demand contract request will not affect any existing
contracts.

### Emergency mode

The emergency mode can only be activated by the pilot and is normally
cancelled by the pilot. While it is possible for some ground systems to
cancel the emergency mode status, most ground systems do not have this
capability although some ground systems can control the "display" of the
emergency mode status to the controller. The pilot normally activates
the ADS emergency mode automatically by sending a CPDLC

MAYDAY message, although the ADS emergency mode can also be set
independently. When the ADS emergency mode is set, the aircraft
immediately sends an ADS report containing an emergency flag that
is[^48]

interpreted by all ground systems that currently have periodic or event
contracts established with that aircraft. The aircraft does not
automatically send an ADS report at the time that the emergency mode is
set.

When the pilot cancels the emergency mode, the aircraft will send an
emergency mode cancellation message to each ground station receiving the
emergency mode reports with the next periodic report, whenever it may be
due. The cancellation message will remove the emergency flag from the
periodic contract, but the data contents will remain the same as per the
emergency contract. Any previously existing data groups requested by the
ground system will not be restored unless the ground system
re-negotiates the periodic contract following receipt of the emergency
cancellation message. Existing event contracts are unaffected by the
emergency cancellation.[^49]

Note: the Boeing B717 and B737 models will send the ADS emergency
cancellation message immediately after being selected by the pilot.[^50]

## Factors To Be Considered When Using ADS

### Vertical and lateral variations 

Where the Altitude Range Change Event and Lateral Deviation Event
contracts are established, the controller will only be specifically
alerted to vertical or lateral variations that exceed the associated
tolerances.

Note: If a regular periodic report is sent as the aircraft is deviating
from cleared level or route (but still within the level or lateral
tolerances) the controller will still be alerted to the variation
despite no event report having been sent. [^51]

### Figure of Merit (FOM) data in ADS reports

ADS reports contain FMS information relating to the Figure of Merit
(FOM), ACAS/TCAS and the aircraft\'s navigational redundancy. Some
automated ground systems use the FOM value received in an ADS report to
determine whether to display the report to controllers, or to display a
\"high\" or \"low\" quality ADS symbol.

FOM data is **not** required for the use of current separation
standards. However, where the separation standard being applied requires
specific navigational accuracy, such as RNP, controllers shall rely on
pilot advice as to the extent of any navigational degradation and shall
adjust separation accordingly.

### Flight crew modification of active route

The flight crew will often insert non-ATS waypoints into the active
flight plan in the FMS for flight system

monitoring, or will modify the active route for planning purposes. Once
the change is activated, a Waypoint Change Event report may be
triggered. If so, non-ATS waypoints included in the active flight plan
will be reflected in the Predicted Route Group, as well as the
Intermediate and Fixed Projected Intent Groups,[^52] which

may result in the next, or the next-plus-one waypoints from the report
not being waypoints expected in the ATS flight plan or flight data
record.

## ADS Connection Management

### Priority for the ADS connection 

FANS-1/A equipped aircraft can have up to five ADS connections. One of
the five connections is reserved for use by the AOC. The aircraft has
the capacity to report to four different ATSUs simultaneously using ADS.

The FANS-1/A system does not assign any technical priority to ADS
connections; therefore the controlling ATSU may not be aware of other
connections established with the aircraft. As a result, a procedural
hierarchy controlled by the Address Forwarding process (FN_CAD message)
has been established.

#### Allocation of ADS connections

Using the Address Forwarding process, the current controlling authority
shall allocate ADS connection priority to the next ATSU that will have
air traffic control responsibility for the aircraft. The priority for
the allocation of ADS connections shall be in accordance with the
following list:

1.  The Current Data Authority,

2.  The Next Data Authority,

3.  An ATSU requiring a connection for monitoring operations close to a
    boundary,

4.  Airline AOC

5.  Other miscellaneous connections.

### Near boundary ADS connections

#### Monitoring of an aircraft operating close to an airspace boundary

When an aircraft will operate within the defined coordination parameter
of the boundary with an adjacent ADS-capable FIR, controllers shall
determine during coordination whether that ATSU requires an ADS contract
to monitor the aircraft's progress near the boundary.

![](media/image11.wmf)

Figure 10: Priorities for ADS connections

*An ADS contract is required by ATSU 2 to monitor the aircraft's
progress near the FIR boundary. To ensure that the next unit with direct
control responsibility for the aircraft has priority over the ADS
connections, Address Forwarding to ATSU 3 will be initiated by ATSU 1
prior to Address Forwarding to ATSU 2.*

#### Other ground facilities requesting ADS contracts

All ground facilities, without having direct control or monitoring
requirements for that aircraft, seeking an ADS contract with a specific
aircraft (e.g. for ADS test purposes) must coordinate with the
controlling authorities and the operator prior to the departure of the
flight.

### ADS connections not available

When all available ADS connections with a particular aircraft have been
established (see Figure 2), any other ATSUs attempting to connect with
the aircraft will receive an ADS DISCONNECT REQUEST message with
\"reason code 1\" (Congestion).

When an ADS DISCONNECT REQUEST is received by an ATSU, which would
normally have priority for an ADS connection, the current controlling
authority should be notified. The controlling authority shall resolve
the situation.

The controlling authority has a number of options available, such as
coordination with the previous ATSU or other adjacent ATSUs to ensure
that existing ADS connections are still required, or when considered
absolutely necessary, instructing the pilot to turn the ADS application
off and turn it on again. The latter option will terminate all current
ADS contracts; therefore, the controlling authority should consider the
operational effect on other ATSUs prior to employing this method.

Once all contracts have been terminated, the controlling authority shall
allocate priority for the connections to other ATSUs via the Address
Forwarding process. Only ATSUs with direct control or monitoring
responsibilities shall re-establish contracts with the aircraft.

![](media/image12.wmf)

Figure 11: ADS connection not available

*The aircraft has ADS connections with four ground facilities and the
airline AOC:*

*Connection: 1 - with ATSU 1,*

*2 - with ATSU 2,*

*3 - with the previous controlling authority,*

*4 - with the airline AOC,*

> *5 - with a ground facility collecting test data.*

*ATSU 3, the next controlling authority, is unable to establish an ADS
connection with the aircraft due to congestion.*

### Ground system termination of ADS connections

The termination of ADS contracts with an aircraft, whether performed
automatically or manually, should be strictly monitored to avoid
situations leading to congestion. ADS contracts and connections should
be terminated by the ground system when the:

-   Aircraft has crossed an FIR boundary and has passed beyond the
    normal "back coordination" parameter; or

-   Aircraft's flight plan has been cancelled or has finished; or

-   Previous ATSU, the controlling authority or an adjacent ATSU has no
    further surveillance or monitoring requirements for a particular
    flight.

## Reporting Rates

### General

There are a number of situations where a controller may consider the use
of a reporting rate other than that used as the default in the periodic
reporting contract. Some automated systems have the capability of
defining reporting rates that can automatically change from one area to
another along the route segment to take into account changes in traffic
density along the route.

Where the ground system does not contain the ability to automatically
change the reporting rate, the controller should take action, where
possible, to manually change the periodic reporting rate when
operationally required. Some examples where a change to the rate may be
required are:

-   When the aircraft is approaching a crossing route on which there is
    other traffic;

-   When the aircraft is approaching areas of known significant weather;

-   During periods of turbulence; or

-   When an unauthorized deviation from the clearance is detected.

### Appropriate reporting rates

ATSUs should ensure that the periodic reporting rate in use is in
accordance with the position reporting requirements of the separation
standards being used. When not required for the application of
separation, or other factors, ATSUs should consider using less frequent
periodic reporting rates for individual aircraft to reduce overall costs
to the system.

### Avoid high periodic reporting rates

Arbitrarily selecting high periodic reporting rates adds undue economic
costs and unnecessarily loads the data link system.

### Other factors to be considered

Depending on individual circumstances the controlling authority should
limit the periodic reporting rate to not more frequently than five (5)
minutes. Adjacent ATSUs with ADS contracts established with the same
aircraft should restrict the periodic reporting rate to not more
frequently than 15 minutes unless coordination is performed with the
controlling authority and the controlling authority agrees to reduce any
relatively high reporting rate currently in effect.

### Default periodic reporting rates

When setting a default periodic reporting rate, ATSUs should take into
account factors such as conformance with ATC clearance requirements,
traffic levels, alerting service requirements, and separation standard
requirements.

## Separation 

ADS may be used for the application of procedural separation within a
mixed surveillance environment, such as airspace where position reports
are provided by a mixture of ADS, CPDLC and voice.

For example, ADS may be used to determine separation between two or more
aircraft reporting by ADS, between ADS and non-ADS aircraft, between ADS
aircraft and an aircraft identified on radar, and to ensure separation
between ADS aircraft and special use airspace, such as military
restricted areas.

### Appropriate ADS reporting requirements

When position reporting is being provided via ADS, to ensure that
estimates being used for the application of separation are accurate
ATSUs should establish appropriate:

-   ADS contracts; and

-   Periodic reporting frequencies.

### Appropriate separation standard

A separation standard to be applied in a mixed surveillance environment
must be appropriate to the communications and navigational capability of
the relevant aircraft. In the case of separation being applied between
ADS and non-ADS aircraft, the separation standard must be appropriate to
the capabilities of the non-ADS aircraft.

### Vertical separation

#### Vertical tolerance consistency 

Where practical, the tolerances used to determine whether a specific
level is occupied by an ADS reporting aircraft within the airspace of a
specific ATSU should be consistent with other tolerances used throughout
the airspace. For example, the vertical tolerances for ADS should be
consistent with vertical tolerances used for level adherence monitoring
by other forms of surveillance, such as radar.

#### Application of vertical tolerances

Where other vertical tolerances do not exist, the vertical tolerances to
be applied for ADS shall be (±) 300 feet. However, an individual ATSU
may specify in local instructions and the AIP that a tolerance of not
less than (±) 200 feet will be used to provide consistency with other
vertical tolerances applied within the FIR.

#### ADS level information does not satisfy vertical tolerance

If displayed ADS level information does not satisfy the required
tolerance for an individual ATSU then the pilot shall be advised
accordingly and requested to confirm the aircraft\'s level. If following
confirmation of the level the displayed ADS level information is still
beyond the required tolerance, another method of separation or another
method of determining level information may need to be applied.

#### Use of ADS level information

When displayed ADS level information is within the specified tolerance
of the expected or cleared flight level, the ADS level information may
be used for the application of vertical separation, and to determine
that an aircraft has reached or is maintaining a specified level.

#### Passing or leaving a level

An aircraft can be considered to have left a specified level when the
displayed ADS level information indicates that the aircraft has passed
the level in the required direction by more than the required tolerance.

### Longitudinal separation

#### Limitations on the use of tools

ATSUs that use approved or integrated measurement tools for the purpose
of determining screen-based separation should publish in local
documentation any limitations on the use of such tools for the
establishment and monitoring of separation standards.

#### Establishing longitudinal separation

ADS reports may be used to establish and monitor longitudinal time and
distance separation standards.

#### Using extrapolated or interpolated positions

Some ground systems display an extrapolated or interpolated ADS symbol
between the receipt of ADS reports. Providing that the periodic
reporting rate in use is in accordance with any reporting rate required
by the separation standard, separation may be determined between the
extrapolated/interpolated symbols by the use of screen-based measurement
tools, or by the use of automated conflict detection tools.

#### Validity of displayed information

When extrapolated or interpolated ADS symbols are being used to provide
separation and any doubt exists as to the integrity or validity of the
information being presented, the controller shall send a Demand Contract
Request to update the relevant information. If doubt still exists, the
controller should consider the use of an alternative method of
separation.

#### Time-based separation

Ground system flight data records updated by ADS reports may be used in
the application of appropriate time-based separation standards. Methods
of determination may include reference to:

-   Estimates at actual waypoints;

-   Calculated estimates for positions not contained in the ATS flight
    plan;

-   Screen-based measurement tools; or

-   Automated conflict detection tools.

#### .Distance-based separation 

ADS reports may be used for the application of appropriate longitudinal
distance standards. Methods of determination may include:

-   The use of automated system tools to measure the displayed positions
    of two or more aircraft reporting by ADS;

-   Comparing the displayed position of an ADS aircraft with the
    position of another aircraft determined by an alternative form of
    surveillance; or

-   The use of automated conflict detection tools.

### Lateral separation

#### Areas of lateral conflict

ADS reports can be used to determine whether an aircraft is within or
beyond an area of lateral conflict. Where

lateral conflict calculations are not made by automated conflict
detection tools, an ADS report[^53] observed

outside an area of lateral conflict displayed or calculated on the
screen is confirmation that the aircraft is outside the area of
conflict.

## Air Traffic Clearance Monitoring

ADS reports can be used to monitor conformance with air traffic
clearances.

### Deviations from ATC clearances

The pilot of an ADS aircraft observed to deviate significantly from its
cleared flight profile shall be advised accordingly. The controller
shall also take action as appropriate if such deviation is likely to
affect the air traffic service being provided.

## Coordination

### Duty of care responsibility

As airlines bear the cost of datalink communications, ATSUs should be
aware of Duty of Care responsibility issues when ADS and other
technologies allow the surveillance of aircraft and the possible
detection of conflicts inside another ATSU\'s airspace. Local ATS
instructions and/or Letters of Agreement between units should detail the
coordination response required from one ATSU in the case of a suspected
conflict being detected in the adjacent ATSU\'s airspace. Unless
required for safety purposes, ATSUs should ensure that ADS is only
enabled for aircraft inside their Area of Interest.[^54]

### Coordinated data inconsistent with ADS displayed data

The transferring controller shall advise during coordination if the
aircraft is currently at a level or on a route different from that
intended for the boundary crossing. When the coordination information
relating to the transfer of control is different from the displayed ADS
information and the required advice has not been provided, the receiving
controller shall confirm the coordinated information with the
transferring controller.

## Alerting service 

For ADS-equipped aircraft, the provision of the alerting service should
be based on the scheduled position reports provided by the periodic
reporting contract.

### Late or missing ADS Reports

Whenever an ADS report (either a periodic or waypoint report) is not
received within a parameter of the expected time, the controller should
initiate a demand contract request or establish a new periodic contract
with the aircraft

## Aircraft Navigation

### Aircraft in heading select mode 

When the aircraft is in Heading Select Mode, the intent and predicted
route information being transmitted by the aircraft will project towards
the next FMS flight plan waypoint regardless of the actual position and
heading of the aircraft. Predicted information is based on the FMS
intent, which may not necessarily be the intent of the pilot.

If the aircraft is in Heading Select Mode, and the aircraft passes abeam
a flight planned waypoint by more than a defined parameter the FMS will
not sequence this or subsequent waypoints. The effect on a ground system
of a waypoint that has not been sequenced is that the intent
information, once the aircraft has passed the waypoint, will be directed
back towards the non-sequenced waypoint. As a result, some ground
systems may see an extrapolated symbol move in a different direction to
the actual track of the aircraft.

### Sequencing subsequent waypoints

If a waypoint is passed abeam by more than the aircraft FMS parameter
while flying in Heading Select Mode, the FMS must be re-programmed (e.g.
to fly direct to the next relevant waypoint) to enable subsequent
waypoints to be sequenced.

(See also CPDLC Sequencing "ABEAM" waypoints in excess of FMS
parameters)

## Position Reporting

### Position reporting requirements in ADS airspace

ATSUs using integrated Flight Data Processing Systems (FDPS)
automatically updated by ADS reports may promulgate in the AIP that ADS
reports fulfil all normal position reporting requirements within the
nominated FIR.

#### Publishing reporting requirements

ATSUs should publish ADS and CPDLC position reporting requirements in
the AIP.

#### CPDLC report at FIR entry position

When an ATSU has nominated the use of ADS reporting only within the
associated FIR, a CPDLC position report at the FIR entry position is
still required to confirm that the ATSU holds the status of Current Data
Authority. Following the initial CPDLC report at the boundary, no
further CPDLC or voice position reports will be required for operations
within the FIR.

#### Updating waypoint estimates

ATSUs should publish in the AIP that pilots are not required to update
estimates for waypoints when the aircraft is reporting by ADS in
airspace where additional CPDLC or voice reports are not required.
Exceptions to this rule are that updates to estimates are required when:

-   An estimate previously advised by voice or CPDLC will change by more
    than 2 minutes; or

-   A pilot-initiated action, such as a change in speed, will change the
    estimate for the next reporting point by more than 2 minutes.

#### Non-compulsory waypoints

When reporting by ADS only, the flight crew is **not** required to
modify the route to remove non-compulsory waypoints. Waypoint event
reports will be sent at all non-compulsory reporting points and will be
reflected in the predicted route group.

### Discrepancies between ADS and CPDLC estimates

Controllers should be aware that CPDLC and ADS estimates received from
the same aircraft for the same

position may differ as a result of the ADS application reporting time to
the second and the time reported by CPDLC application either being
truncated or rounded to the nearest full minute (depending on aircraft
type).[^55]

The pilot also has the ability to modify the estimate for the next
position in the CPDLC position report. Any such modification will not be
reflected in the ADS report.

####  Actions to be followed when there is an estimate discrepancy

When an ATSU is using both ADS and CPDLC reporting and a discrepancy of
less than 3 minutes between the reports is detected, the ATSU should
detail in local documentation methods to be used by the controller for
the reconciliation of the time difference. Where the time difference
exceeds 3 minutes, the controller shall query the estimate received in
the CPDLC position report and request confirmation of the estimate for
the waypoint in question.

# Emergency and Non-routine Procedures

## Emergency procedures

An emergency CPDLC message such as **[Mayday]{.smallcaps}** or
**[Pan]{.smallcaps}** does not require a response, however pilots have
indicated a preference that the CPDLC emergency declaration is
acknowledged by the controller

### Response to an emergency message

When a CPDLC or ADS emergency message is received the controlling
authority, in order to better assess the nature of the emergency should
either:

a\) Increase the PERIODIC contract reporting rate to 5 minutes, or

b\) Send an ON DEMAND contract request. (Note. This is not required if
the periodic reporting rate has been increased -- an ADS report will
have already been triggered by the avionics when the new periodic
contract is received).

Note. Increasing the ADS reporting rate also reduces the period between
cancellation of the ADS emergency and receipt of the ADS Cancel
Emergency downlink.[^56]

### Confirmation of emergency activation

When the ADS emergency mode is activated without a CPDLC emergency
message or voice confirmation, and the demand contract report appears to
indicate that the aircraft is maintaining normal operations (e.g. the
aircraft is not in descent or involved in abrupt maneuvers), the
aircraft may be subject to unlawful interference. To check for covert or
inadvertent activation of the ADS emergency mode the freetext uplink
"Confirm ADS" shall be appended to a "Confirm Speed" data or voice
request:

  ---------------- --------------------------------------------------------
  **Controller**   Confirm Speed

                   Confirm ADS
  ---------------- --------------------------------------------------------

The pilot shall then check the status of the aircraft's ADS Emergency
Mode and if the emergency mode has been activated inadvertently, the
pilot shall select ADS Emergency Mode to "OFF" and advise ATC by voice
or the following CPDLC freetext downlink.

  -------------- --------------------------------------------------------
  **Pilot**      ADS reset

  -------------- --------------------------------------------------------

If the aircraft continues with the ADS emergency mode activated ATC
shall assume the aircraft is in emergency conditions and follow normal
alerting procedures.

### Acknowledgement of an emergency message

When an ADS emergency accompanied by a CPDLC emergency message is
received, the controller shall immediately acknowledge receipt of the
emergency with the pilot by the most appropriate means (voice or CPDLC).

### CPDLC acknowledgment

A CPDLC acknowledgment shall be in the form of a free text message using
the words ROGER MAYDAY or ROGER PAN. This uplink free text message
requires a response from the pilot to close the CPDLC exchange.
Depending on the nature of the emergency, the free text message may or
may not be acknowledged by the pilot.

####  Voice contact

When an emergency is acknowledged by CPDLC, controllers may also attempt
to make voice contact with the aircraft.

### Retaining the active connection

If CPDLC is the best (or only) communications medium available between
the aircraft and any ATSU, the ATSU with the active connection should
maintain that connection until better assistance can be provided by
another means. In this case, transfer of the connection should not occur
to another unit, and any automatic transfer capability should be
disabled, if possible,[^57] in order to improve the chances of the CPDLC
connection

being retained.

#### Communications responsibility

It is recognized that if a transfer of the CPDLC connection does not
occur, then the responsibility for maintaining communications with the
aircraft is retained by the current ATSU.

#### Executive control responsibility

In accordance with established procedures, the responsibility for the
control of the flight rests with the ATSU within whose airspace the
aircraft is operating. If the pilot takes action contrary to a clearance
that has already been coordinated with another sector or ATSU and
further coordination is not possible in the time available, then this
action would be performed under the pilot's emergency authority.

### Normal emergency procedures

After receipt of the emergency message is acknowledged, normal emergency
response procedures shall be followed.

### Coordination in the case of emergency

When the ADS emergency mode is observed by an ATSU that is not in
control of the aircraft, that ATSU shall coordinate with the controlling
authority to ensure that the emergency report has been received.
Adjacent ATSUs shall not increase the reporting rate of the periodic
contract.

## Data Link Connection Failures

### Detected by the controller

When the controller recognizes a failure of the data link connection,
the controller shall instruct the pilot to terminate the connection, by
selecting ATC Com Off, and then initiate another AFN logon. Once the AFN
logon

is established, the ATS system should[^58] send a **[Connection
Request]{.smallcaps}** message to re-establish the connection.

> The voice phraseology to be used shall be:

+-----------+----------------------------------------------------------+
| **Con     | Data link failed.                                        |
| troller** |                                                          |
|           | Select ATC Com Off then Logon to \[ATSU name\][^59]      |
+-----------+----------------------------------------------------------+
| **Pilot** | Roger                                                    |
+-----------+----------------------------------------------------------+

> *The \[ATSU name\] is the 4 character ICAO code.*

### Detected by the airborne system

When the avionics/pilot recognizes a failure of the data link
connection, the pilot shall terminate the connection

by selecting ATC Com Off and then initiate a new AFN logon (FN_CON) to
the current controlling authority.[^60]

### Inability to establish the data link connection

In situations where a data link connection cannot be established
successfully, the ATS system should indicate to the controller that no
connection has been established.

## Data link System Shutdowns

### Unexpected data link shutdowns

In the event of an unexpected data link shutdown, the relevant ATSU
shall inform:

-   All currently connected FANS-1/A equipped aircraft via voice;

> The voice phraseology to be used shall be:

+-----------+----------------------------------------------------------+
| **Con     | Data link failed.                                        |
| troller** |                                                          |
|           | Select ATC Com Off. Continue on voice                    |
+-----------+----------------------------------------------------------+
| **Pilot** | Roger                                                    |
+-----------+----------------------------------------------------------+

-   The adjacent ATSUs by direct coordination; and

-   All relevant parties via the publication of a NOTAM, if appropriate.

Pilots shall terminate the data link connection and use voice until
informed by the ATSU that the data link system has resumed normal
operations.

### Planned data link shutdowns

When a planned data link system shutdown of the communications network,
or of the ATS system, occurs a NOTAM shall be published to inform all
affected parties of the shutdown period. During that time period, voice
shall be used.

The following voice or data phraseology shall be used to advise airborne
aircraft prior to the commencement of the shutdown.

+-----------+----------------------------------------------------------+
| **Con     | Data link will be shutdown.                              |
| troller** |                                                          |
|           | Select ATC Com Off. Continue on voice                    |
|           |                                                          |
|           | *(The pilot shall select ATC Com Off when the message is |
|           | received)*                                               |
+-----------+----------------------------------------------------------+
| **Pilot** | Roger                                                    |
+-----------+----------------------------------------------------------+

### Resumption of data link operations

The following voice phraseology shall be used to advise pilots that the
data link system has resumed operations.

+-----------+----------------------------------------------------------+
| **Con     | Data link operational                                    |
| troller** |                                                          |
|           | Logon to \[ATSU name\]                                   |
+-----------+----------------------------------------------------------+
| **Pilot** | Logon \[ATSU name\]                                      |
+-----------+----------------------------------------------------------+

> *The \[ATSU name\] is the 4 character ICAO code.*

### Data link component shutdown

Some ATSUs are not equipped with both CPDLC and ADS and consequently may
experience shutdown of a single component of the data link system (i.e.
CPDLC or ADS). For those ATSUs that have both CPDLC and ADS it is not
likely that just one component will shutdown, however it is possible.

ATSUs experiencing a shutdown of either CPDLC or ADS shall follow the
procedures above for data link shutdowns as appropriate.

#### ADS only failure

When a shutdown of the ground component of the ADS system occurs, the
ATSU affected shall inform all other affected parties of the shutdown
and likely period. During that time period, position reports (via CPDLC
if available, or via voice) will be required.

If a CPDLC service is still available, a CPDLC free text message shall
be sent to the pilot notifying reporting requirements. The following
phraseology shall be used:

  ---------------- ---------------------------------------------------------
  **Controller**   ADS shutdown revert to ATC data link position reports

  **Pilot**        Roger
  ---------------- ---------------------------------------------------------

### Unexpected communication service provider shutdown

In the event of an unexpected communications service provider system,
the communications service providers shall inform ATSUs and airline
dispatch of the situation. ATSUs shall consequently inform:

-   All currently connected FANS equipped aircraft via voice,

> The voice phraseology to be used shall be:

+-----------+----------------------------------------------------------+
| **Con     | Data link failed                                         |
| troller** |                                                          |
|           | Select ATC Com Off. Continue on voice                    |
+-----------+----------------------------------------------------------+
| **Pilot** | Roger                                                    |
+-----------+----------------------------------------------------------+

-   The adjacent ATSUs by direct coordination,

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```
-   All relevant parties via the publication of a NOTAM, if appropriate.

Pilots shall terminate [CPDLC]{.smallcaps} connections with the ATSU and
use voice communications until informed by the ATSU that the system is
again fully functional.

### Unexpected avionics system shutdown

In the event of an unexpected avionics data link shutdown, pilots shall
inform the ATSU of the situation using voice.

> The voice phraseology to be used shall be:

+-----------+----------------------------------------------------------+
| **Pilot** | Data link failed.                                        |
|           |                                                          |
|           | Selecting ATC Com Off. Continuing on voice               |
+-----------+----------------------------------------------------------+
| **Con     | Roger. Continue on voice                                 |
| troller** |                                                          |
+-----------+----------------------------------------------------------+

Pilots shall continue to use voice until the functionality of the
avionics can be re-established.

## Total Communications Failure

The procedures covering complete communications failure (CPDLC and
voice) shall be in accordance with current ICAO procedures.

## Using CPDLC to relay messages

When an ATSU and an aircraft cannot communicate, and an intermediary
data link aircraft is used for relaying messages, the following shall
apply:

-   Only a free text message shall be used;

-   The first word in the message shall be "RELAY".

*Note: The use of pre-formatted messages is prohibited because the
intermediary aircraft's FMS could be unintentionally armed.*

Example

  ------------- ---------------------------------------------------------
  Controller\   Relay. \[atsu\] clears \[call-sign\] Climb to and
  (all Free     maintain F340
  text)         

  ------------- ---------------------------------------------------------

  ------------- ---------------------------------------------------------
  Pilot\        Relay from \[call-sign\] Climbing F340
  (all Free     
  text)         

  ------------- ---------------------------------------------------------

# FANS-1/A Implementation

## Introduction

This Part provides information of FANS-1/A datalink implementations by:

-   Japan, Australia, Fiji, New Zealand, Tahiti and the United States

-   Aircraft manufacturers

## ATSU Designators

### ICAO

The Pacific ICAO facility designations (called also "4 character ICAO
code") are:

**[ATS Units]{.underline}** **[ICAO Facility Designation]{.underline}**

Anchorage PAZA

Auckland NZZO

Brisbane YBBB

Melbourne YMMM

Nadi NFFF

Oakland KZAK

Tahiti NTTT

Tokyo RJTG

### ACARS ADDRESSES

The following are the ATSU addresses lodged in the ACARS system, for the
Pacific:[^61]

**[ATS System]{.underline} [ATSU Address]{.underline}**

OCS -- Anchorage ANCXFXA

OCS -- Auckland AKLCDYA

TAAATS -- Brisbane BNECAYA

TAAATS -- Melbourne MELCAYA[^62]

Eurocat 2000X -- Nadi NANCDYA

ODL -- Oakland OAKODYA

VIVO -- Tahiti PPTCDYA

ODP-3 -- Tokyo TYOTGYA

## HF Voice Communications Requirements

### Pre-Departure

All South Pacific ATSUs require a SELCAL check prior to departure. In
the North and Central Pacific only those aircraft, including aircraft
equipping with FANS-1/A datalink, intending to operate in the North and
Central Pacific airspace using a Selective Calling System (SELCAL) to
fulfill communications listening watch requirements, should conduct a
SELCAL check prior to departure.

### Crossing International FIR Boundaries

When entering a Pacific FIR from an adjacent international FIR and CPDLC
is serviceable, the HF instruction [Contact]{.smallcaps} or
[Monitor]{.smallcaps} datalink message shall be sent as detailed below:

**[FIR]{.underline}** **[HF Instruction]{.underline}**

Anchorage Oceanic [Contact PAZA Center \[]{.smallcaps}frequency\]

Auckland Oceanic [Contact NZZO Center \[]{.smallcaps}frequency\]

Brisbane [Contact YBBB Center \[]{.smallcaps}frequency\]

Melbourne [Contact YMMM Center \[]{.smallcaps}frequency\]

Nadi [Contact NFFF Center \[]{.smallcaps}frequency\]

Oakland [Contact KSFO Center \[]{.smallcaps}frequency\]

*KSFO (San Francisco Radio) will provide all primary and secondary HF
frequencies, and HF transfer points along the route of flight.*

Tahiti [Contact NTTT Center \[]{.smallcaps}frequency\]

*A SELCAL check is required.*

Tokyo [Contact Tokyo Center \[]{.smallcaps}frequency\]

### CPDLC Services Within The Tokyo FIR

Initial notification of emergency status may be accepted by CPDLC.
Depending on the nature of the emergency condition experienced, the
pilot should notify ATC of the circumstances by the most efficient means
(voice or CPDLC).

Clearances/instructions relating to cruise climb are not issued within
the Tokyo FIR. Therefore, downlink request DL#8 "REQUEST CRUISE CLIMB TO
\[ level \]" should not be used.

Pre-formatted messages regarding route modifications, including route
clearance are not able to be uplinked. These messages include UL#79,
UL#80, UL#81, UL#83, UL#84, UL#85 and UL#86 detailed in APPENDIX 5.
CONTROLLER-PILOT DATA LINK COMMUNICATIONS (CPDLC) MESSAGE SET of the
ICAO PANS/ATM. The route clearance should, therefore be requested and
issued by HF or VHF voice communication.

Special and other non-routine aircraft observation, i.e. moderate
turbulence (transonic and supersonic aircraft only), severe turbulence,
and volcanic activity should be reported by HF or VHF voice
communication.

Flight information services will be provided by HF or VHF voice
communication.

### Logon Procedures within the Tokyo FIR

Datalink-equipped aircraft inbound from non-datalink airspace or radar
airspace to Tokyo Oceanic Controlled airspace are required to log on
between 15 and 45 minutes prior to entering datalink airspace within the
Tokyo FIR. On initial contact with Tokyo Radio, the pilot should inform
Tokyo Radio that they have the CPDLC connection using the voice
phraseology "WE HAVE CPDLC CONNECTION", and should downlink a CPDLC
position report.

Datalink-equipped aircraft inbound from the Anchorage FIR or Oakland FIR
to Tokyo Oceanic Controlled airspace will be automatically transferred
to "RJTG" by Anchorage or Oakland. If the process is not successful and
"RJTG" is not the active center, the pilot shall, within 5 minutes after
crossing the Tokyo and Anchorage/Oakland common FIR boundary, terminate
the connection by selecting ATC datalink off, then log on with "RJTG".
Once a CPDLC connection has been established with "RJTG (Tokyo ACC)",
the pilot should inform Tokyo Radio that they have the CPDLC connection
using the voice phraseology "WE HAVE CPDLC CONNECTION", and should
downlink a CPDLC position report.

## Differences of Use of FANS-1/A Messages 

The Pacific States listed in the box on the right do NOT use these two
messages.

  ------ ------ ---------------------- -----------------------------------
  33     UL     Cruise \[altitude\]    *Australia, Fiji, Japan, New
                                       Zealand, and Tahiti do not use this
                                       message*.

  129    UL     Report                 *The United States has not used
                level\[altitude\]      this message, but will be phasing
                                       it in during the 2003-4 time
                                       period.*
  ------ ------ ---------------------- -----------------------------------

## Position Reporting Requirements: CPDLC and ADS Environments

The following table lists the position reporting requirements of
individual ATSUs in the Pacific.

  ----------------- -----------------------------------------------------
  **ATSU**          **Reporting Requirements**

  Anchorage         Does not accept CPDLC position reports in lieu of HF
                    voice

  Auckland          Requires an initial CPDLC position report at the FIR
                    boundary entry point, then ADS reporting only.

  Brisbane          Requires an initial CPDLC position report at the FIR
                    boundary entry point, then ADS reporting only.

  Melbourne         Requires an initial CPDLC position report at the FIR
                    boundary entry point, then ADS reporting only.

  Nadi              Currently accepts CPDLC position reports. Following
                    the commissioning of the EASY system Fiji will
                    require an initial CPDLC position report at the FIR
                    boundary entry point, then ADS reporting only.

  Oakland           Accepts CPDLC position reports in lieu of HF voice.

  Tahiti            Accepts CPDLC position reports. Controllers will send
                    a free text request for an FIR boundary estimate for
                    outbound flights.

  Tokyo             Accepts CPDLC position reports in lieu of HF voice.
  ----------------- -----------------------------------------------------

## Aircraft Data

### Verifying registration number

  -----------------------------------------------------------------------
  **A330-A340**

  On Airbus aircraft, the pilot could not initially change the
  registration number provided by the avionics. This will be possible in
  the second version of ATSU, and this change will then be reflected in
  the FN_CON message.

  **B747-400 (up to Load 14)**

  On the B747-400 aircraft, the pilot cannot change the registration
  number in the FN_CON message. This number is provided by the avionics.

  **B747-400 (Load 15)/B777 / B757-B767 / B717 / MD90 / MD10 / MD11**

  These aircraft do not have an ***essential*** data source for this
  datum, which means that the pilot must verify that the registration
  number is correct.
  -----------------------------------------------------------------------

###   {#section .unnumbered}

### CPDLC connection requests

+-----------------------------------------------------------------------+
| **A330-A340**                                                         |
+-----------------------------------------------------------------------+
|                                                                       |
+-----------------------------------------------------------------------+
| **B747-400 / B777 / B757-B767 / B717 / MD90 / MD10 / MD11**           |
+-----------------------------------------------------------------------+
| -   The only **[Connection Request]{.smallcaps}** message processed   |
|     normally by FANS-1 is the first **[Connection                     |
|     Request]{.smallcaps}** following an AFN logon (i.e., an AFN logon |
|     initiated when no CPDLC connection exists).                       |
|                                                                       |
| -   If the CPDLC connection in the avionics is not terminated, and a  |
|     new AFN logon transmitted, before sending the new **[Connection   |
|     Request]{.smallcaps}** message any subsequent **[Connection       |
|     Request]{.smallcaps}** messages received from that ATSU are       |
|     processed, however they have no effect on the "active" connection |
|     (i.e. the avionics is not informed of an ATS system shutdown and  |
|     will therefore consider that the original connection is still     |
|     active).                                                          |
|                                                                       |
| -   The avionics will not accept a connection if the AFN logon is     |
|     initiated manually by the pilot while another connection was      |
|     active, even if the active connection is terminated before the    |
|     connection from the new ATSU is received                          |
+-----------------------------------------------------------------------+

### Flight crew display:- response and acknowledgment

+-----------------------------------------------------------------------+
| **A330-A340**                                                         |
+-----------------------------------------------------------------------+
| In response to an uplink message that requires a closure response     |
| (WILCO, ROGER, AFFIRM, UNABLE, NEGATIVE), the pilot is presented with |
| prompts corresponding to the closure responses required by DO-219 for |
| the specific uplink message. EG prompts presented upon receipt of an  |
| uplink clearance are [**Wilco**, **Unable**]{.smallcaps}, and         |
| **[Standby]{.smallcaps}**.                                            |
+-----------------------------------------------------------------------+
| **B747-400 / B777 / B757-B767 / B717 / MD90 / MD10 / MD11**           |
+-----------------------------------------------------------------------+
| In response to an uplink message that requires a response element     |
| (**[Wilco, Roger]{.smallcaps}**, **[Affirm]{.smallcaps}**,            |
| **[Unable]{.smallcaps}** or **[Negative)]{.smallcaps}**, the pilot is |
| presented with two prompts (**Accept** and **Reject**).               |
|                                                                       |
| -   If the correct response to the uplink message is affirmative      |
|     (**[Wilco, Roger]{.smallcaps}**, or **[Affirm)]{.smallcaps}**,    |
|     then the pilot will select the **Accept** prompt.                 |
|                                                                       |
| -   If the correct response to the uplink message is negative         |
|     (**[Unable]{.smallcaps}** or **[Negative)]{.smallcaps}**, then    |
|     the pilot will select the **Reject** prompt.                      |
|                                                                       |
| When the pilot selects either the **Accept** or the **Reject**        |
| prompt, the FANS-1 automatically transmits the correct response       |
| (**[Wilco, Roger]{.smallcaps}**, **[Affirm, Unable,]{.smallcaps}** or |
| **[Negative)]{.smallcaps}** for the corresponding message.            |
|                                                                       |
| On the FANS-1 equipped aircraft, the pilot cannot add any other       |
| element to a positive response.                                       |
+-----------------------------------------------------------------------+

### FMS processing of waypoints

+-----------------------------------------------------------------------+
| **A330-A340**                                                         |
+-----------------------------------------------------------------------+
| The FMS cannot distinguish between ATC mandatory waypoints and        |
| waypoints inserted by the pilot. However, the pilot can over-write    |
| any avionics-determined default data contained in reports and confirm |
| messages.                                                             |
+-----------------------------------------------------------------------+
| **B747-400**                                                          |
+-----------------------------------------------------------------------+
| The FMC's on Boeing aircraft do not distinguish between ATC mandatory |
| waypoints and FMC sequenced waypoints for position reports.           |
| Additionally, the FANS-1 of the B747-400 aircraft does not permit the |
| pilot to overwrite the FMC-determined default "reported waypoint"     |
| position in downlink DL#45 - **[Reported waypoint.]{.smallcaps}**     |
| However, the FANS-1 of the B747-400 aircraft does allow the pilot to  |
| overwrite the FMC-determined default time (in particular, in response |
| to uplink UL#138 -[**Confirm time over reported                       |
| waypoint**)]{.smallcaps}.                                             |
|                                                                       |
| **Non-use of uplink UL#139 for B747-400 aircraft**                    |
|                                                                       |
| The uplink message UL#139 - **[Confirm reported                       |
| waypoint]{.smallcaps}** should not be sent to B747-400 aircraft.      |
+-----------------------------------------------------------------------+
| **B777 / B757-B767 / B717 / MD90 / MD10 / MD11**                      |
+-----------------------------------------------------------------------+
| The FMC's on Boeing aircraft do not distinguish between ATC mandatory |
| waypoints and FMC sequenced waypoints for position reports. However,  |
| the FANS-1 of these aircraft will allow the pilot to overwrite the    |
| FMC-determined default "reported waypoint" position and time          |
| (Downlink element DL#45)                                              |
+-----------------------------------------------------------------------+

### Multiple request messages

+-----------------------------------------------------------------------+
| **A330-A340**                                                         |
+-----------------------------------------------------------------------+
| There is no network acknowledgment timer on Airbus aircraft for the   |
| establishment of a connection. Once CPDLC is established, there is a  |
| timer which is currently set at 2 minutes.                            |
+-----------------------------------------------------------------------+
| **B747-400**                                                          |
+-----------------------------------------------------------------------+
| If the network acknowledgment to a downlink message is not received   |
| by the B747-400 aircraft's ACARS MU within a time period set in the   |
| Navigation Database or Operational Program Configuration (OPC) file,  |
| the FANS-1 closes the message and an alert is triggered to the pilot. |
| This alert may prompt the pilot to re-send the message. The timer     |
| value was 2 minutes up to Load 14, but will be set to 5 minutes with  |
| the introduction of Load 15. If a second message is identical to the  |
| first, but with a different identification number, and both messages  |
| have been received and responded to by the controller the avionics    |
| will only recognize the reference number of the second message. The   |
| first message is considered by the avionics to have been              |
| unsuccessful.                                                         |
|                                                                       |
| -   In reply to the controller's response to the first message, the   |
|     avionics will send an **[Invalid Reference Number                 |
|     error.]{.smallcaps}**                                             |
|                                                                       |
| -   The controller's response to the second message will be processed |
|     normally.                                                         |
|                                                                       |
| In this case, if the controller ignores the first message, the        |
| connections to both ATS systems will not be lost when an **[End       |
| Service]{.smallcaps}** message is received on board the aircraft.     |
+-----------------------------------------------------------------------+
|                                                                       |
+-----------------------------------------------------------------------+

  -----------------------------------------------------------------------
  **B757-B767 / B717 / MD90 / MD10 / MD11**

  When the network acknowledgment timer expires, it just "unlocks" the
  request pages, so that the pilot will be able to send another one. The
  time at which the network acknowledgement timer expires can be set in
  the Operational Program Configuration (OPC) file in the FMS. Currently,
  the value is set to 5 minutes.

  **B777**

  This network acknowledgment timer does not apply to the B777.
  -----------------------------------------------------------------------

### Waypoint sequencing 

  -----------------------------------------------------------------------
  **A330-A340**

  Waypoint sequencing will only occur when the aircraft is within 7 NM of
  the flight plan track (as modified by any parallel offset that may have
  been entered). Therefore ADS waypoint change event reports and armed
  REPORT PASSING messages will not be transmitted automatically when the
  aircraft is outside these limits.

  **B747-400 / B757-B767 / B777 / MD90**

  Waypoint sequencing will only occur when the aircraft is within 21 NM
  of the flight plan track (as modified by any parallel offset that may
  have been entered). Therefore ADS waypoint change event reports and
  armed REPORT PASSING messages will not be transmitted automatically
  when the aircraft is outside these limits.

  **B717 / MD10 / MD11**

  Waypoint sequencing will only occur when the aircraft is within 7 NM of
  the flight plan track (as modified by any parallel offset that may have
  been entered). Therefore ADS waypoint change event reports and armed
  REPORT PASSING messages will not be transmitted automatically when the
  aircraft is outside these limits.
  -----------------------------------------------------------------------

### Network acknowledgement timer

  -----------------------------------------------------------------------
  **B747-400**

  The B747-400 FMC has a network acknowledgment timer as described in
  section 6.6.2A.i. of the Reference 1 ATS SR&O. If the network
  acknowledgment to a downlink message is not received before the timer
  expires, the flight crew is alerted and may assume that the message has
  not been sent. Once back "IN COMM" the ACARS MU will transmit any
  "queued" messages.
  -----------------------------------------------------------------------

### Open uplinks at time of transfer of communications

  -----------------------------------------------------------------------
  **B747-400 (Load 15)**

  If there are OPEN uplinks in the Boeing B747-400 FMC\'s ATC LOG when
  the Current Data Authority initiates transfer of communication to the
  Next Data Authority, the FMC will allow transfer to the Next Data
  Authority (i.e. The FMC will not disconnect the next data authority).
  This allows a smooth transfer to the next Flight Information Region if
  there are open uplinks at the time of transfer.
  -----------------------------------------------------------------------

### Offset using the FMS

When a pilot is flying an FMS offset, the Airbus and Boeing parameters
previously mentioned (7 NM and 21 NM respectively) are not an issue as
all flight plan waypoints will be sequenced by the FMS without taking
into account the offset distance being flown. However, when an offset is
executed using the FMS, Boeing aircraft and Airbus aircraft will
transmit intent and predicted route information as follows:

+-----------------------------------------------------------------------+
| **A330-A340**                                                         |
+-----------------------------------------------------------------------+
| The Intent and Predicted Route Group information is projected along   |
| the offset route.                                                     |
+-----------------------------------------------------------------------+
| **B747-400 / B777 / B757-B767 / B717 / MD90 / MD10 / MD11**           |
+-----------------------------------------------------------------------+
| The Predicted Route Group when flying an FMS offset is always along   |
| the offset route.                                                     |
|                                                                       |
| The projection of intent information currently depends on the         |
| aircraft type, and the version of software is installed as defined    |
| below:                                                                |
|                                                                       |
| B747-400 - Load 14 and before, towards the next FMS waypoint. Load 15 |
| and after, along the offset path.                                     |
|                                                                       |
| B757/B767 - Pegasus 99 and before, towards the next FMS waypoint.     |
| Pegasus 2000 and after, along the offset path.                        |
|                                                                       |
| B777 - Block Point 98, towards the next FMS waypoint. Block Point 99  |
| and after, along the offset path.                                     |
|                                                                       |
| MD90 - 920 FMS, towards the next FMS waypoint. 921 FMS and after,     |
| along the offset path.                                                |
|                                                                       |
| MD10 / MD11 / B717 - Always along the offset path.                    |
+-----------------------------------------------------------------------+

### Duplicate uplink messages

+-----------------------------------------------------------------------+
| **B747-400 (Load 15)**                                                |
+-----------------------------------------------------------------------+
| If the Boeing B747-400 FMC receives an uplink message that is an      |
| exact duplicate of a previously received uplink message, the FMC will |
| discard the duplicate message. This prevents the display of the       |
| INVALID ATC UPLINK scratch pad message which would otherwise be       |
| displayed when a duplicate uplink is received                         |
|                                                                       |
| *Note: Duplicate messages are an unavoidable characteristic of the    |
| datalink environment.*                                                |
+-----------------------------------------------------------------------+

## FANS Interoperability Team Members

Both the IPACG and ISPACG FANS Interoperability Teams (FITs) consist of
representatives from aircraft and ancillary equipment manufacturers,
airlines, data communication service providers, ATS providers, IATA,
ICAO, IFALPA and IFATCA. Contact details of the FIT members are
available from their respective CRAs (refer below).

## Central Reporting Agency Members

### North and Central Pacific (IPACG)

+--------------------------------+-------------------------------------+
| **[FAA CRA]{.smallcaps}**      |                                     |
+--------------------------------+-------------------------------------+
| Reed Sladen                    | Fax: +1-510-745-3826                |
|                                |                                     |
| Special Assistant - Pacific    | Tel: +1-510-745-3328                |
|                                |                                     |
| FAA Oceanic and Offshore IPT   | EM: <Reed.B.Sladen@faa.gov>         |
|                                |                                     |
| Oakland ARTC Center            |                                     |
|                                |                                     |
| 5125 Central Avenue            |                                     |
|                                |                                     |
| Fremont, CA 94536 -- USA       |                                     |
+--------------------------------+-------------------------------------+
| **[FAA CRASA --                |                                     |
| Boeing]{.smallcaps}**          |                                     |
+--------------------------------+-------------------------------------+
| William M. Fisher              | Fax: +1 253 773 4934                |
|                                |                                     |
| Air Traffic Management         | Tel: +1 253 773 7836                |
|                                |                                     |
| The Boeing Company             | EM: <william.m.fischer@boeing.com>  |
|                                |                                     |
| P.O. Box 3707, MS 02-JH        |                                     |
|                                |                                     |
| SEATTLE, WA 98124-2207 -- USA  |                                     |
+--------------------------------+-------------------------------------+
| Gordon Sandell                 | Fax: +1 425 294 3558                |
|                                |                                     |
| Avionics Engineering           | Tel: +1 425 342 4765                |
|                                |                                     |
| The Boeing Company             | EM: <gordon.r.sandell@boeing.com>   |
|                                |                                     |
| P.O. Box 3707, MC 0R-HK        |                                     |
|                                |                                     |
| SEATTLE, WA 98124-2207 -- USA  |                                     |
+--------------------------------+-------------------------------------+

+--------------------------------+---+-------------------------------------+
| **[JCAB CRA]{.smallcaps}**     |   |                                     |
+--------------------------------+---+-------------------------------------+
| Masahiro Kudo                  |   | Fax: +81-3-5253-1663                |
|                                |   |                                     |
| Director for International     |   | Tel: +81-3-5253-8739                |
| Policy Coordination            |   |                                     |
|                                |   | EM: kudou-m2ct@mlit.go.jp           |
| ATS Systems Planning Division  |   |                                     |
|                                |   |                                     |
| Civil Aviation Bureau,         |   |                                     |
|                                |   |                                     |
| Ministry of Land,              |   |                                     |
| Infrastructure and Transport   |   |                                     |
|                                |   |                                     |
| 2-1-3 Kasumigaseki, Chiyoda-ku |   |                                     |
|                                |   |                                     |
| Tokyo 100-8918 - JAPAN         |   |                                     |
+--------------------------------+---+-------------------------------------+
| **[JCAB CRASA]{.smallcaps}**   |   |                                     |
+--------------------------------+---+-------------------------------------+
| Yoshiro Nakatsuji              | F |                                     |
|                                | a |                                     |
| JCAB CRASA                     | x |                                     |
|                                | : |                                     |
| K-1 Building, 3rd floor,       | + |                                     |
|                                | 8 |                                     |
| 1-6-6 Haneda airport, Ota-ku,  | 1 |                                     |
|                                | - |                                     |
| Tokyo 144-0041 -- JAPAN        | 3 |                                     |
|                                | - |                                     |
|                                | 3 |                                     |
|                                | 7 |                                     |
|                                | 4 |                                     |
|                                | 7 |                                     |
|                                | - |                                     |
|                                | 1 |                                     |
|                                | 2 |                                     |
|                                | 3 |                                     |
|                                | 1 |                                     |
|                                |   |                                     |
|                                | T |                                     |
|                                | e |                                     |
|                                | l |                                     |
|                                | : |                                     |
|                                | + |                                     |
|                                | 8 |                                     |
|                                | 1 |                                     |
|                                | - |                                     |
|                                | 3 |                                     |
|                                | - |                                     |
|                                | 3 |                                     |
|                                | 7 |                                     |
|                                | 4 |                                     |
|                                | 7 |                                     |
|                                | - |                                     |
|                                | 1 |                                     |
|                                | 2 |                                     |
|                                | 3 |                                     |
|                                | 1 |                                     |
|                                |   |                                     |
|                                | E |                                     |
|                                | M |                                     |
|                                | : |                                     |
|                                | C |                                     |
|                                | R |                                     |
|                                | A |                                     |
|                                | S |                                     |
|                                | A |                                     |
|                                | @ |                                     |
|                                | c |                                     |
|                                | r |                                     |
|                                | a |                                     |
|                                | - |                                     |
|                                | j |                                     |
|                                | a |                                     |
|                                | p |                                     |
|                                | a |                                     |
|                                | n |                                     |
|                                | . |                                     |
|                                | o |                                     |
|                                | r |                                     |
|                                | g |                                     |
+--------------------------------+---+-------------------------------------+
| Kenji Shibata                  | F |                                     |
|                                | a |                                     |
| JCAB CRASA                     | x |                                     |
|                                | : |                                     |
| K-1 Building, 3rd floor,       | + |                                     |
|                                | 8 |                                     |
| 1-6-6 Haneda airport, Ota-ku,  | 1 |                                     |
|                                | - |                                     |
| Tokyo 144-0041 -- JAPAN        | 3 |                                     |
|                                | - |                                     |
|                                | 3 |                                     |
|                                | 7 |                                     |
|                                | 4 |                                     |
|                                | 7 |                                     |
|                                | - |                                     |
|                                | 1 |                                     |
|                                | 2 |                                     |
|                                | 3 |                                     |
|                                | 1 |                                     |
|                                |   |                                     |
|                                | T |                                     |
|                                | e |                                     |
|                                | l |                                     |
|                                | : |                                     |
|                                | + |                                     |
|                                | 8 |                                     |
|                                | 1 |                                     |
|                                | - |                                     |
|                                | 3 |                                     |
|                                | - |                                     |
|                                | 3 |                                     |
|                                | 7 |                                     |
|                                | 4 |                                     |
|                                | 7 |                                     |
|                                | - |                                     |
|                                | 1 |                                     |
|                                | 2 |                                     |
|                                | 3 |                                     |
|                                | 1 |                                     |
|                                |   |                                     |
|                                | E |                                     |
|                                | M |                                     |
|                                | : |                                     |
|                                | C |                                     |
|                                | R |                                     |
|                                | A |                                     |
|                                | S |                                     |
|                                | A |                                     |
|                                | @ |                                     |
|                                | c |                                     |
|                                | r |                                     |
|                                | a |                                     |
|                                | - |                                     |
|                                | j |                                     |
|                                | a |                                     |
|                                | p |                                     |
|                                | a |                                     |
|                                | n |                                     |
|                                | . |                                     |
|                                | o |                                     |
|                                | r |                                     |
|                                | g |                                     |
+--------------------------------+---+-------------------------------------+

### South Pacific (ISPACG)

+--------------------------------+-------------------------------------+
| **CRA and CRASA -- Boeing**    |                                     |
+--------------------------------+-------------------------------------+
| Brad D. Cornell                | Fax: 425 294-1076                   |
|                                |                                     |
| Air Traffic Management         | EM: bradley.d.cornell@boeing.com    |
| Services                       |                                     |
|                                | SITA: FMCBOCR                       |
| The Boeing Company             |                                     |
|                                | Tel: 425-294-0540                   |
| P.O. Box 3707, MS 02-JH        |                                     |
|                                | Fax: 425 342-6078                   |
| SEATTLE, WA 98124-2207 - USA   |                                     |
|                                | EM: suzie.ness@boeing.com           |
| Suzie NESS                     |                                     |
|                                | SITA: FMCBOCR                       |
| FMS                            |                                     |
|                                | Tel: 425-342-6803                   |
| The Boeing Company             |                                     |
|                                | Fax: +1 253 773 4934                |
| P.O. Box 3707, MS 02-RP        |                                     |
|                                | Tel: +1 253 773 7836                |
| SEATTLE, WA 98124-2207 -- USA  |                                     |
|                                | EM: william.m.fischer@boeing.com    |
| William M. Fisher              |                                     |
|                                |                                     |
| Air Traffic Management         |                                     |
|                                |                                     |
| The Boeing Company             |                                     |
|                                |                                     |
| P.O. Box 3707, MS 02-JH        |                                     |
|                                |                                     |
| SEATTLE, WA 98124-2207 -- USA  |                                     |
+--------------------------------+-------------------------------------+

# Continental CPDLC Implementation

## Introduction

This section provides guidance on the implementation of FANS-1/A
datalink operations in en route continental (domestic) airspace based on
the operational experience of a number of centres that are using CPDLC
as a supplement to VHF voice. The purpose of this guidance material is
to ensure that the concepts and procedures for continental FANS-1/A data
link usage are globally standardized as far as is possible. The
recommended procedures contained in this section are drawn from
procedures that have been validated over several years of operational
use within continental en route airspaces.

## Concepts

### Supplement to Voice

Implementation of CPDLC into continental airspace is intended as a
supplement to the use of VHF voice and the intent is to build a single
communications environment where both voice and CPDLC are considered as
being normal Air Traffic Management (ATM) tools.

### Reduced Message Set

CPDLC in continental airspace uses a reduced set of message elements as
a supplement to VHF voice communications. A recommended message sub-set
is included at the end of this section, but it is expected that there
may be slight variations from centre to centre depending on specific
environments. It is extremely important that Air Traffic Service
Providers publish a list of the functions that will be served by CPDLC
so that crew expectations can be modified from one environment to the
next.

### Airspace

The use of CPDLC in continental airspace is intended primarily for
aircraft operating within en-route sectors. Depending on the actual
operational environment where the implementation is to occur (for
example, radar or non-radar airspace), the only change to the single
communications environment during the progression of a specific flight
would be the mix of voice and CPDLC transmissions. As an example of the
changing mix of media in a single communications environment, a
non-radar environment might use a roughly equal mix of voice and CPDLC,
whereas the use of CPDLC might possibly be restricted to just the
passing of Departure Clearances in some busier terminal environments.

## Communications Media

### Continental

The ATC communications environment within data link enabled continental
airspace is a defined mix of CPDLC and voice media.

### Use of CPDLC in Continental Airspace

The following procedures only apply to normal (non-emergency)
operations. While the intent of these procedures is to develop a
standardised and predictable environment using a combination of voice
and CPDLC, the decision on whether voice or CPDLC is the more
appropriate medium for use in a given operational situation will be made
by the pilots and controllers involved.

### Strategic CPDLC Application

As a supplement to VHF voice, CPDLC is intended to be restricted to the
passing of strategic information. Strategic information involves
routine, non-time-critical communications, and includes examples such as
the passing of amended flight levels, amended routes, speed control
messages, frequency changes, and SSR codes, when the speed of delivery
is not critical to safety.

### Tactical Voice

Tactical, time-critical instructions, such as intervention required to
maintain separation, are intended to be handled by voice communications.

### Voice Precedence 

Voice instructions and acknowledgments shall have precedence over CPDLC
messages at all times. In the event that any ambiguity exists in a
message or message exchange, then the controller/pilot shall revert to
voice communications for clarification.

### Imposing Voice Communications

If a controller or pilot believes that the presiding operational
circumstances are not suitable for the use of CPDLC, then either may
suspend the use of CPDLC. Whenever voice is required to be the sole
communications medium, notification shall be made by the following
phraseologies:

Controller initiated suspension - "\[callsign\] CPDLC use suspended.
Revert to voice."

Pilot initiated suspension - "\[callsign\] suspending CPDLC. Reverting
to voice."

Note: Notification of CPDLC being suspended is intended to ensure that
CPDLC is not used during the prevailing circumstances -- the crew should
not initiate a disconnection from CPDLC unless specifically advised by
the controller. If a disconnection from CPDLC is required, then either
the phrase "\[callsign\] Select ATC Comm Off" shall be used, or the
controller will perform the disconnection via the ground system.

### Change from Strategic to Tactical Situation

If the traffic situation should quickly change to the point where the
controller no longer believes that there is sufficient time for a
datalink exchange to be completed without safety, separation, or
situational awareness being affected, then the controller should revert
to voice. Any previously issued CPDLC clearance or instruction that is
being overridden by the change to voice shall be specifically referred
to in the voice communication. Where necessary, any open CPDLC messages
resulting from a sudden change from CPDLC to voice should only be dealt
with after the tactical situation has been resolved.

### Message Compliance and Responses

Flight crew shall either comply with uplink CPDLC instructions or
respond with UNABLE, and shall respond to uplink messages using CPDLC
whenever possible.

### Climb/Descent Phase

Due to cockpit workload and crew head-down time in busier phases of
flight, consideration should be given to the types of messages exchanged
by CPDLC during the climb and descent phases and whether those messages
provide operational benefit over voice transmissions.

### Crossing CPDLC System Boundaries 

Flight crew shall ensure that the correct centre is displayed as the
Active Centre following a transfer of the CPDLC connection from one ATS
Unit to another.

### Jurisdiction Over Aircraft

Controllers must ensure that CPDLC clearances are sent only to aircraft
under their jurisdiction.

### Dialogues During CPDLC Transfer 

Flight crew and controllers should not initiate a CPDLC dialogue within
two minutes of a boundary crossing when the transfer of CPDLC will occur
from one ATS Unit to another.

## Message Set

The following message set is the recommended maximum sub-set of the full
CPDLC message set for continental CPDLC use. This sub-set has been
defined from a mix of proposed and current message elements intended for
continental use by a number of States:

MAAS Maastricht Upper Area Control Center (UAC)

Miami 1A FAA Build 1A Program (Miami Centre)

Only messages relating to the listed elements should be used in
continental airspace, with all other transactions being conducted by VHF
voice.

Note 1: This list is presented as an example of the types and range of
operational message elements that should be considered for continental
CPDLC operations.

Note 2: For ease of cross-referencing, the table is drawn from a mix of
ATN and FANS-1/A message environments, and the element text presented in
the table is from the ATN Baseline 1 program message set. If a conflict
occurs with the message text between the FANS-1/A and ATN elements, the
element number should be used for determining the actual element text
relevant to the FANS-1/A environment. Ground system implementations will
ensure that the correct element (based on the message number) will be
delivered to the receiving system.

Note 3: Although these procedures are written to be applicable across
technologies, they will initially be included in FANS-1/A specific
documentation (i.e. the Pacific Operations Manual). For this reason,
only the FANS-1/A message elements are listed in the following tables.
Some of the facilities listed in the table (e.g. Miami and Maastricht)
also use ATN-specific message elements not available in FANS-1/A. For
the purposes of this document, such elements are represented by the
\[freetext\] elements because these non-FANS elements would be converted
to free text for FANS operations.

For example, Maastricht uses um190 \[degrees\], an ATN message
instructing the crew to FLY HEADING \[degrees\]. In the context of this
document this message would be sent as um169 \[freetext\], e.g.um169
\[FLY HEADING nnn\].

### Recommended Uplink Message Set

  ------------------------------------------------------------------------------------------------------
  Elmt   Maas         Miami         Message                                                           
  \#                  1A            Element                                                           
  ------ ------ ----- ------- ----- ------------ ---------------------------------------------------- --
  0      X            X             UNABLE                                                            

  1      X            X             STANDBY                                                           

  3      X            X             ROGER                                                             

  4      X                          AFFIRM                                                            

  5      X                          NEGATIVE                                                          

  19     X            X             MAINTAIN                                                          
                                    \[level\]                                                         

  20     X            X             CLIMB TO                                                          
                                    \[level\]                                                         

  23     X            X             DESCEND TO                                                        
                                    \[level\]                                                         

  26     X                          CLIMB TO                                                          
                                    REACH                                                             
                                    \[level\] BY                                                      
                                    \[time\]                                                          

  27            X                                CLIMB TO REACH \[level\] BY \[position\]             

  28            X                                DESCEND TO REACH \[level\] BY \[time\]               

  29            X                                DESCEND TO REACH \[level\] BY \[position\]           

  46            X             X                  CROSS \[position\] AT \[level\]                      

  47            X             X                  CROSS \[position\] AT OR ABOVE \[level\]             

  48            X             X                  CROSS \[position\] AT OR BELOW \[level\]             

  51            X                                CROSS \[position\] AT \[time\]                       

  52            X                                CROSS \[position\] AT OR BEFORE \[time\]             

  53            X                                CROSS \[position\] AT OR AFTER \[time\]              

  54            X                                CROSS \[position\] BETWEEN \[time\] AND \[time\]     

  55            X             X                  CROSS \[position\] AT \[speed\]                      

  61            X             X                  CROSS \[position\] AT AND MAINTAIN \[level\] AT      
                                                 \[speed\]                                            

  64            X                                OFFSET \[specified distance\] \[direction\] OF ROUTE 

  72            X                                RESUME OWN NAVIGATION                                

  74            X             X                  PROCEED DIRECT TO \[position\]                       

  79                          X                  CLEARED TO \[position\] VIA \[routeClearance\]       

  80            X                                CLEARED \[routeClearance\]                           

  82            X                                CLEARED TO DEVIATE UP TO \[specified distance\]      
                                                 \[direction\] OF ROUTE                               

  92            X                                HOLD AT \[position\] AS PUBLISHED MAINTAIN \[level\] 

  94            X                                TURN \[direction\] HEADING \[degrees\]               

  96            X                                CONTINUE PRESENT HEADING                             

  106           X             X                  MAINTAIN \[speed\]                                   

  107           X                                MAINTAIN PRESENT SPEED                               

  108           X             X                  MAINTAIN \[speed\] OR GREATER                        

  109           X             X                  MAINTAIN \[speed\] OR LESS                           

  116           X                                RESUME NORMAL SPEED                                  

  117           X             X                  CONTACT \[unitname\] \[frequency\]                   

  120           X             X                  MONITOR \[unitname\] \[frequency\]                   

  123           X                                SQUAWK \[code\]                                      

  133           X                                REPORT PRESENT LEVEL                                 

  135           X             X                  CONFIRM ASSIGNED LEVEL                               

  148           X                                WHEN CAN YOU ACCEPT \[level\]                        

  157           X             X                  CHECK STUCK MICROPHONE \[frequency\]                 

  159           X             X                  ERROR \[error information\]                          

  160           X             X                  NEXT DATA AUTHORITY \[facility\]                     

  161           X                                END SERVICE                                          

  162           X             X                  SERVICE UNAVAILABLE                                  

  163           X                                \[facility designation\]                             

  165           X             X                  THEN (only used when concatenated)                   

  169           X                                (freetext)                                           

  171           X                                CLIMB AT \[vertical rate\] MINIMUM                   

  172    X                          CLIMB AT                                                          
                                    \[vertical                                                        
                                    rate\]                                                            
                                    MAXIMUM                                                           

  173    X                          DESCEND AT                                                        
                                    \[vertical                                                        
                                    rate\]                                                            
                                    MINIMUM                                                           

  174    X                          DESCEND AT                                                        
                                    \[vertical                                                        
                                    rate\]                                                            
                                    MAXIMUM                                                           

  179    X                          SQUAWK IDENT                                                      
  ------------------------------------------------------------------------------------------------------

### Recommended Downlink Message Set

+----+----+-----+-----------------------------------------------------+
| El | Ma | Mi  | Message Element                                     |
| mt | as | ami |                                                     |
| \# |    |     |                                                     |
|    |    | 1A  |                                                     |
+====+====+=====+=====================================================+
| 0  | X  | X   | WILCO                                               |
+----+----+-----+-----------------------------------------------------+
| 1  | X  | X   | UNABLE                                              |
+----+----+-----+-----------------------------------------------------+
| 2  | X  | X   | STANDBY                                             |
+----+----+-----+-----------------------------------------------------+
| 3  | X  | X   | ROGER                                               |
+----+----+-----+-----------------------------------------------------+
| 4  | X  | X   | AFFIRM                                              |
+----+----+-----+-----------------------------------------------------+
| 5  | X  | X   | NEGATIVE                                            |
+----+----+-----+-----------------------------------------------------+
| 6  | X  | X   | REQUEST \[level\]                                   |
+----+----+-----+-----------------------------------------------------+
| 9  | X  | X   | REQUEST CLIMB TO \[level\]                          |
+----+----+-----+-----------------------------------------------------+
| 10 | X  | X   | REQUEST DESCENT TO \[level\]                        |
+----+----+-----+-----------------------------------------------------+
| 18 | X  |     | REQUEST \[speed\]                                   |
+----+----+-----+-----------------------------------------------------+
| 22 | X  |     | REQUEST DIRECT TO \[position\]                      |
+----+----+-----+-----------------------------------------------------+
| 23 | X  |     | REQUEST \[procedure\]                               |
+----+----+-----+-----------------------------------------------------+
| 24 | X  |     | REQUEST \[routeClearance\]                          |
+----+----+-----+-----------------------------------------------------+
| 26 | X  |     | REQUEST \[weather deviation\]                       |
+----+----+-----+-----------------------------------------------------+
| 27 | X  |     | REQUEST WEATHER DEVIATION UP TO \[distance\]        |
|    |    |     | \[direction\] OF ROUTE                              |
+----+----+-----+-----------------------------------------------------+
| 37 | X  |     | MAINTAINING \[level\]                               |
+----+----+-----+-----------------------------------------------------+
| 38 | X  | X   | ASSIGNED LEVEL \[level\]                            |
+----+----+-----+-----------------------------------------------------+
| 40 | X  |     | CONFIRM ROUTE                                       |
+----+----+-----+-----------------------------------------------------+
| 56 | X  |     | MAYDAY MAYDAY MAYDAY                                |
+----+----+-----+-----------------------------------------------------+
| 62 | X  | X   | ERROR \[error information\]                         |
+----+----+-----+-----------------------------------------------------+
| 63 | X  | X   | NOT CURRENT DATA AUTHORITY                          |
+----+----+-----+-----------------------------------------------------+
| 64 | X  |     | \[facility designation\]                            |
+----+----+-----+-----------------------------------------------------+
| 65 | X  | X   | DUE TO WEATHER (only used when concatenated)        |
+----+----+-----+-----------------------------------------------------+
| 66 | X  | X   | DUE TO AIRCRAFT PERFORMANCE (only used when         |
|    |    |     | concatenated)                                       |
+----+----+-----+-----------------------------------------------------+
| 73 |    | X   | \[versionnumber\]                                   |
+----+----+-----+-----------------------------------------------------+
| 80 | X  |     | DEVIATING UP TO \[specified distance\]\[direction\] |
|    |    |     | OF ROUTE                                            |
+----+----+-----+-----------------------------------------------------+

[^63]

# Index

A

ACARS i, v, 2-1, 4-2, 4-3, 5-2, 8-1, 8-5, 8-6

Aircraft

A330 8-3, 8-4, 8-5, 8-6, 8-7

A340 8-3, 8-4, 8-5, 8-6, 8-7

B717 3-2, 6-2, 8-3, 8-4, 8-5, 8-6, 8-7

B737 6-2

B747 3-1, 3-10, 5-25, 8-3, 8-4, 8-5, 8-6, 8-7

B757 3-1, 8-3, 8-4, 8-5, 8-6, 8-7

B767 3-1, 8-3, 8-4, 8-5, 8-6, 8-7

B777 3-1, 3-10, 8-3, 8-4, 8-5, 8-6, 8-7

MD10 3-2, 8-3, 8-4, 8-5, 8-6, 8-7

MD11 3-2, 3-10, 8-3, 8-4, 8-5, 8-6, 8-7

MD90 3-1, 8-3, 8-4, 8-5, 8-6, 8-7

D

Downlink Message

008 8-2

045 8-5

048 5-8

067 5-8

068 5-8

F

FN_AK 4-7

FN_CAD ii, 4-5, 4-6, 6-3

FN_CON i, 4-3, 4-7, 7-2, 8-3

Freetext message

AT WHAT DISTANCE \...WILL YOU MAINTAIN FL 5-26

CHECK ATC LOG PAGE FOR OPEN MESSAGES 4-8, 5-26

EXPECT CPDLC TRANSFER AT 4-11, 5-27

EXPECT NEXT CENTER \... CONTACT WITH \... NOT REQUIRED 5-28

EXPECT SELCAL CHECK HF 5-26

EXPECT TO MAINTAIN 5-28

REPORT ETA 5-25

REPORT ETA 5-25

REPORT GROUND SPEED 5-25

REPORT GROUND SPEED 5-25

REPORT RADIAL AND DISTANCE 5-26

REPORT SIGHTING AND PASSING OPPOSITE DIRECTION 5-25

REQUEST VOICE CONTACT 5-21, 5-26

[Revised ETA]{.smallcaps} [5-9]{.smallcaps}, 5-29

ROGER MAYDAY 5-28, 7-1

ROGER PAN 5-28, 7-1

SECONDARY HF 5-28

STATE PREFERRED LEVEL 5-25

STATE PREFERRED LEVEL 5-25

TRAFFIC IS 5-28

[Wake Dev]{.smallcaps} [5-5]{.smallcaps}, 5-29

WHEN WILL YOU MAINTAIN FL 5-26

I

IATA 2-1, 8-8

ICAO v, 2-1, 3-1, 3-10, 4-1, 4-3, 4-6, 4-10, 5-2, 5-25, 5-28, 7-2, 7-3,
7-4, 8-1, 8-2, 8-8

IFALPA 2-1, 8-8

IFATCA 2-1, 8-8

IPACG 1-7

P

PANS/ATM 3-1, 4-1, 5-8, 8-2

R

RTCA 2-2, 3-1, 3-2, 3-3

RVSM 2-2, 5-5, 5-29

U

Uplink Message

019 5-5

020 5-5

021 5-5

022 5-5

024 5-5

025 5-5

028 5-5

033 5-2

079 8-2

080 8-2

081 8-2

083 8-2

084 8-2

085 8-2

086 8-2

117 4-8, 5-1

118 5-1

119 5-1

120 5-1

121 5-1

122 4-8, 5-1

129 5-5

138 8-5

139 8-5

147 5-9

169 5-2

UPR iii, [5-5]{.smallcaps}, [5-6]{.smallcaps}, 5-8

# Endnotes

[^1]: This paragraph was inserted by the editor to explain how changes
    would be documented within the POM.

[^2]: Sections 1.8 "Page Checklist" and 1.9 "Change Sheet" have been
    removed because the design of the POM, its infrequent updates
    (several times a year), and the fact that it is only distributed
    electronically all conspire against a "page change" philosophy. The
    editor expects that the reader will simply replace the old POM with
    the new, which will -- as explained above -- indicate where and why
    changes were made.

[^3]: RFC 03-003

[^4]: RFC 03-003

[^5]: RFC 02-009

[^6]: RFC 03-004

[^7]: RFC 03-004

[^8]: RFC 03-004

[^9]: RFC 03-004

[^10]: RFC 03-004

[^11]: RFC 03-004

[^12]: RFC 03-004

[^13]: RFC 03-004

[^14]: RFC 02-012

[^15]: RFC 03-004

[^16]: RFC 02-012

[^17]: RFC 03-004

[^18]: RFC 02-012

[^19]: RFC 03-004

[^20]: RFC 03-004

[^21]: RFC 03-012

[^22]: RFC 03-004

[^23]: RFC 03-004

[^24]: RFC 03-004

[^25]: RFC 03-014

[^26]: RFC 03-005

[^27]: RFC 03-001

[^28]: RFC 03-005

[^29]: RFC 03-010

[^30]: RFC 03-005

[^31]: RFC 02-011

[^32]: RFC 02-011

[^33]: RFC 03-013

[^34]: RFC 03-002

[^35]: RFC 03-005

[^36]: RFC 03-005

[^37]: RFC 03-005

[^38]: RFC 03-005

[^39]: RFC 03-006

[^40]: RFC 03-006

[^41]: RFC 03-009

[^42]: RFC 03-009

[^43]: RFC 03-007

[^44]: RFC 03-007

[^45]: RFC 03-007

[^46]: RFC 03-007

[^47]: RFC 03-007

[^48]: RFC 02-008

[^49]: RFC 02-008

[^50]: RFC 02-008

[^51]: RFC 03-007

[^52]: RFC 03-007

[^53]: RFC 03-007

[^54]: RFC 03-007

[^55]: RFC 03-007

[^56]: RFC 03-008

[^57]: RFC 03-008

[^58]: RFC 03-008

[^59]: RFC 03-008

[^60]: RFC 03-008

[^61]: RFC 03-011

[^62]: RFC 03-011

[^63]: RFC 02-010