AC 120-28D

July 13, 1999

CRITERIA FOR APPROVAL OF

CATEGORY III WEATHER MINIMA

FOR TAKEOFF, LANDING, AND ROLLOUT

07/13/99 AC 120-28D

1. Purpose. This advisory circular (AC) provides an acceptable means, but not the only means, for

obtaining and maintaining approval of operations in Category III Landing Weather Minima and low

visibility takeoff including the installation and approval of associated aircraft systems. It includes

additional Category III criteria or revised Category III criteria for use in conjunction with Head-up

Displays, satellite navigation systems, low visibility takeoff guidance systems, Wide-body Fail Passive

operations and use of Category III during certain engine inoperative operations. This revision also

updates and incorporates provisions of the former AC 20-57 into AC 120-28.

This revision incorporates changes resulting from the first steps toward international all weather

operations (AWO) criteria harmonization taken by the Federal Aviation Administration (FAA),

European Joint Aviation Authorities (JAA), and several other regulatory authorities. Subsequent

revisions of this AC are planned as additional all weather operations harmonization items (AHI) are

agreed and completed by FAA JAA, and other regulatory authorities.

L. Nicholas Lacey

Director, Flight Standards Service

07/13/99 AC 120-28D

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TABLE OF CONTENTS

SEC # SECTION TITLES

1 PURPOSE

2 RELATED REFERENCES AND DEFINITIONS

2.1 Related References

2.2 Definitions

3 BACKGROUND

3.1 Major Changes Addressed in this Revision

3.2 Relationship of Operational Authorizations for Category III and Airborne System

Demonstrations

3.3 Applicable Criteria

4 OPERATIONAL CONCEPTS

4.1 Classification and Applicability of Minima

4.2 Takeoff

4.3 Landing

4.3.1 Concepts and Objectives

4.3.2 Fail Operational Category III Operations

4.3.3 Alert Height

4.3.4 Fail Passive Category III Operations

4.3.5 Decision Altitude (Height)

4.3.6 Go-Around Safety

4.3.7 Category IIIa

4.3.8 Category IIIb

4.3.9 Runway Field-Length

4.3.10 Landing System Sensors (NAVAIDs) and Aircraft Position Determination

4.3.10.1 Instrument Landing System(ILS)

4.3.10.2 Microwave Landing System (MLS)

4.3.10.3 GNSS Landing System (GLS)

4.4 RNAV/Flight Management Systems (FMS)

4.5 Required Navigation Performance (RNP)

4.5.1 Standard RNP Types

4.5.2 Non-Standard RNP Types

4.6 Flight Path Definition

4.7 Engine Inoperative Category III Capability

5 AIRBORNE SYSTEMS

5.1 General

5.1.1 Airborne Systems

5.1.2 Non-Airborne Systems

5.1.3 Takeoff Guidance Systems

5.2 Airborne Systems for Category III Minima Not Less Than RVR600

5.3 Airborne Systems for Category III Minima Less Than RVR600

5.3.1 Airborne Systems for Category III Minima Not Less Than RVR400
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5.3.2 Airborne Systems for Category III Minima Not Less Than RVR300 (75 m)

5.3.3 Airborne Systems for Category III Minima Less Than RVR300

5.4 Automatic Flight Control Systems and Automatic Landing Systems

5.5 Flight Director Systems

5.6 Head-up Display Systems

5.7 Enhanced/Synthetic Vision Systems

5.8 Hybrid Systems

5.9 Instruments and Displays

5.10 Annunciations

5.11 Automatic Aural Alerts

5.12 Navigation Sensors

5.13 Supporting Systems and Capabilities

5.13.1 Flight Deck Visibility

5.13.2 Rain and Ice Removal

5.13.3 Miscellaneous Systems

5.14 Go-Around Capability

5.15 Excessive Deviation Alerting

5.16 Rollout Deceleration Systems or Procedures for Category III

5.16.1 Stopping Means

5.16.2 Antiskid Systems

5.17 Engine Inoperative Category III Capability

5.18 Airborne System Assessment for Irregular Pre-Threshold Terrain

5.19 Airworthiness Demonstrations of Airborne System Capability for Category III

6 PROCEDURES

6.1 Operational Procedures

6.1.1 Application of AFM Provisions

6.1.2 Crew Coordination

6.1.3 Monitoring

6.1.4 Use of the Decision Height or Alert Height

6.1.5 Call-outs

6.1.6 Aircraft Configurations

6.1.7 Compatibility with Category I and Category II Procedures

6.1.8 Flight Crew Response to Non-Normal Events

6.2 Category III Instrument Approach Procedures and Low Visibility Takeoff

6.2.1 Takeoff Guidance System Procedures

6.2.2 Acceptable Procedures for Category III Approach

6.2.3 Standard Obstacle Clearance for Approach and Missed Approach

6.2.4 Special Obstacle Criteria

6.2.5 Irregular Terrain Airports

6.2.6 Airport Surface Depiction for Category III Operations

6.2.7 Continuing Category III Approaches in Deteriorating Weather Conditions

6.2.8 Low Visibility Taxi Procedures

6.2.9 Navigation Reference Datum Compatibility (e.g.,WGS-84/Other Datum)

7 TRAINING AND CREW QUALIFICATION

7.1 Ground Training

7.1.1 Ground System and NAVAID’s for Category III
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7.1.2 The Airborne System

7.1.3 Flight Procedures and Associated Information

7.2 Flight Training (Aircraft or Simulator)

7.2.1 Initial Qualification

7.2.2 Recurrent Qualification

7.2.3 Recency of Experience

7.2.4 Re-qualification

7.2.5 Cockpit or Aircraft System Differences

7.2.6 Category III Operations with an Inoperative Engine

7.2.7 Training in Conjunction with Advanced Qualification Programs (AQP) or Exemptions for

“Single Visit Training”

7.2.8 Credit for “High Limit Captains” (Reference section 121.562)

7.2.9 Enhanced or Synthetic Vision Systems (Independent Landing Monitor)

7.3 Checking or Evaluations

7.4 Experience with Line Landings

7.5 Crew Records

7.6 Dual Qualification

7.7 Interchange

7.8 Training For Use of Foreign Airports for Category III Operations or Low Visibility Takeoff

7.9 Line Checks

8 AIRPORTS, NAVIGATION FACILITIES AND METEOROLOGICAL CRITERIA

8.1 Use of Standard Navigation Facilities

8.2 Use of Other Navigation Facilities or Methods

8.3 Lighting Systems

8.4 Marking and Signs

8.5 Low Visibility Surface Movement Guidance and Control (SMGC) Plans

8.6 Meteorological Services and RVR Availability and Use

8.6.1 Meteorological Services

8.6.2 RVR Availability and Use

8.6.2.1 RVR Availability

8.6.2.2 RVR Use

8.6.3 Pilot Assessment of Takeoff Visibility Equivalent to RVR

8.7 Critical Area Protection

8.8 Operational Facilities, Outages, Airport Construction, and NOTAM’s

8.9 Use of Military Facilities

8.10 Special Provisions for Facilities Used for ETOPS or EROPS Alternates

8.11 Alternate Minima

8.12 Flight Planning to Airports That Have Weather Conditions Below Landing Minima

9 CONTINUING AIRWORTHINESS/MAINTENANCE

9.1 Maintenance Program

9.2 Maintenance Program Provisions

9.3 Initial and Recurrent Maintenance Training

9.4 Test Equipment/Calibration Standards

9.5 Return to Service Procedures

9.6 Periodic Aircraft System Evaluations

9.7 Reliability Reporting and Quality Control
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9.8 Configuration Control/System Modifications

9.9 Records

9.10 FAR 129 Foreign Operator Maintenance Programs

9.10.1 Maintenance of FAR 129 Foreign Registered Aircraft

9.10.2 Maintenance of FAR 129 Foreign Operated U.S. "N" Registered Aircraft

10 APPROVAL OF UNITED STATES OPERATORS

10.1 Operations Manuals and Procedures

10.2 Training Programs and Crew Qualification

10.3 Flight Planning (e.g., Dispatch, MEL, Alternate Airports, ETOPS or EROPS)

10.4 Formulation of Operations Specification

10.5 Operational/Airworthiness Demonstrations

10.5.1 Airborne System Suitability Demonstration

10.5.2 "Operator Use Suitability" Demonstration

10.5.2.1 Data Collection For Airborne System Demonstrations

10.5.2.2 Data Analysis

10.5.2.3 Approval of Landing Minima

10.6 Eligible Airports and Runways

10.7 Irregular Pre-Threshold Terrain and Other Restricted Runways

10.8 Engine-Inoperative Operations and ETOPS or EROPS Alternates based on Category III

10.8.1 General Criteria for Engine Inoperative Category III Authorization

10.8.2 Engine Inoperative "Flight Planning"

10.8.3 Engine Inoperative En Route

10.8.4 Engine Failure During Approach, Prior to Alert Height or Decision Height

10.8.5 Engine Failure After Passing Alert Height or Decision Height

10.9 New Category III Operators

10.10 Credit for Experienced Category III Operators for New Authorizations

10.10.1 New Airports/Runways

10.10.2 New or Upgraded Airborne System Capabilities

10.10.3 Adding a New Category III Aircraft Type

10.11 Category III Program Status Following Operator Acquisitions/Mergers

10.12 Initiating New Combined Category II and Category III Programs

10.13 United States Carrier Category III Operations at Foreign Airports

10.14 Category III Operations on Off-Route Charters

10.15 Approval of Category III Minima and Issuance of Operations Specifications

10.16 Operations Specification Amendments

10.17 Use of Specia l Obstacle Clearance Criteria (e.g., RNP Criteria)

10.18 Proof-of-Concept Demonstration for New Systems/Methods

11 FOREIGN AIR CARRIER CATEGORY III AT UNITED STATES AIRPORTS

(Part 129 OPERATIONS SPECIFICATIONS)

11.1 Use of ICAO or FAA Criteria

11.1.1 Acceptable Criteria

11.1.2 Foreign Operator AFM Provisions

11.1.3 Foreign Operator Category III Demonstrations

11.2 Issuance of Part 129 Operations Specifications

11.3 Use of Certain United States Facilities
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12 OPERATOR REPORTING, AND TAKING CORRECTIVE ACTIONS

12.1 Operator Reporting

12.2 Operator Corrective Actions

APPENDIX 1 DEFINITIONS AND ACRONYMS

APPENDIX 2 AIRWORTHINESS APPROVAL OF AIRBORNE SYSTEMS USED DURING A

TAKEOFF IN LOW VISIBILITY WEATHER CONDITIONS

1 APPENDIX 2 PURPOSE

2 APPENDIX 2 GENERAL

3 APPENDIX 2 INTRODUCTION

4 APPENDIX 2 TYPES OF TAKEOFF OPERATIONS

5 APPENDIX 2 TYPES OF TAKEOFF SERVICES

5.1 APPENDIX 2 ILS

5.2 APPENDIX 2 MLS

5.3 APPENDIX 2 GNSS [PoC]

5.3.1 APPENDIX 2 GNSS Flight Path Definition [PoC]

5.3.2 APPENDIX 2 GNSS Airplane Position Determination [PoC]

5.4 APPENDIX 2 Other

5.4.1 APPENDIX 2 Datalink [PoC]

6 APPENDIX 2 AIRWORTHINESS

6.1 APPENDIX 2 General Takeoff System

6.1.1 APPENDIX 2 Takeoff Performance Prior to 35 Ft. AGL

6.1.1.1 APPENDIX 2 ILS

6.1.1.2 APPENDIX 2 MLS

6.1.2 APPENDIX 2 Workload Criteria

6.2 APPENDIX 2 Takeoff System Integrity

6.3 APPENDIX 2 Takeoff System Availability

6.4 APPENDIX 2 Flight Deck Information, Annunciation and Alerting

6.4.1 APPENDIX 2 Flight Deck Information

6.4.2 APPENDIX 2 Annunciation

6.4.3 APPENDIX 2 Alerting

6.4.3.1 APPENDIX 2 Warnings

6.4.3.2 APPENDIX 2 Cautions

6.4.3.3 APPENDIX 2 Advisories

6.4.3.4 APPENDIX 2 System Status

6.4.3.5 APPENDIX 2 Engine Failures

7 APPENDIX 2 TAKEOFF SYSTEM EVALUATION

7.1 APPENDIX 2 Performance Evaluation

7.2 APPENDIX 2 Safety Assessment

8 APPENDIX 2 AIRBORNE SYSTEM
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8.1 APPENDIX 2 General

8.2 APPENDIX 2 Peripheral Vision Guidance Systems [PoC]

8.3 APPENDIX 2 Head Up Display Takeoff System

8.4 APPENDIX 2 Satellite Based Systems [PoC]

8.4.1 APPENDIX 2 Flight Path Definition

8.4.2 APPENDIX 2 On Board Database

8.4.3 APPENDIX 2 Datalink

8.5 APPENDIX 2 Enhanced Vision Systems [PoC]

9 APPENDIX 2 AIRPLANE FLIGHT MANUAL

APPENDIX 3 AIRWORTHINESS APPROVAL FOR AIRBORNE SYSTEMS USED TO LAND

AND ROLLOUT IN LOW VISIBILITY CONDITIONS

1 APPENDIX 3 PURPOSE

2 APPENDIX 3 GENERAL

3 APPENDIX 3 INTRODUCTION

4 APPENDIX 3 TYPES OF LANDING AND ROLLOUT OPERATIONS

5 APPENDIX 3 TYPES OF LANDING AND ROLLOUT SERVICES

5.1 APPENDIX 3 ILS

5.1.1 APPENDIX 3 ILS Flight Path Definition

5.1.2 APPENDIX 3 ILS Airplane Position Determination

5.2 APPENDIX 3 MLS

5.2.1 APPENDIX 3 MLS Flight Path Definition

5.2.2 APPENDIX 3 MLS Airplane Position Determination

5.3 APPENDIX 3 GNSS [PoC]

5.3.1 APPENDIX 3 GNSS Flight Path Definition [PoC]

5.3.2 APPENDIX 3 GNSS Airplane Position Determination [PoC]

5.3.3 APPENDIX 3 Datalink [PoC]

6 APPENDIX 3 AIRWORTHINESS

6.1 APPENDIX 3 General

6.2 APPENDIX 3 Approach Systems

6.3 APPENDIX 3 Landing and Rollout System Performance

6.3.1 APPENDIX 3 Landing System Performance

6.3.2 APPENDIX 3 Speed Control Performance

6.3.3 APPENDIX 3 Rollout System Performance

6.3.4 APPENDIX 3 Variables Affecting Performance

6.3.5 APPENDIX 3 Irregular Approach Terrain

6.3.6 APPENDIX 3 Approach and Automatic Landing with an Inoperative Engine

6.3.7 APPENDIX 3 Inoperative Engine Information

6.4 APPENDIX 3 Landing and Rollout System Integrity

6.4.1 APPENDIX 3 Landing System Integrity

6.4.2 APPENDIX 3 Rollout System Integrity
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6.4.3 APPENDIX 3 On Board Database Integrity [PoC]

6.5 APPENDIX 3 Landing and Rollout System Availability

6.5.1 APPENDIX 3 Landing System Availability

6.5.2 APPENDIX 3 Rollout System Availability

6.6 APPENDIX 3 Go-around

6.7 APPENDIX 3 Automatic Braking System

6.8 APPENDIX 3 Flight Deck Information, Annunciation and Alerting

6.8.1 APPENDIX 3 Flight Deck Information

6.8.2 APPENDIX 3 Annunciation

6.8.3 APPENDIX 3 Alerting

6.8.3.1 APPENDIX 3 Warnings

6.8.3.2 APPENDIX 3 Cautions

6.8.3.3 APPENDIX 3 Advisories

6.8.3.4 APPENDIX 3 System Status

6.9 APPENDIX 3 Multiple Landing Systems

6.9.1 APPENDIX 3 General

6.9.2 APPENDIX 3 Indications

6.9.3 APPENDIX 3 Annunciations

6.9.4 APPENDIX 3 Alerting

7 APPENDIX 3 LANDING AND ROLLOUT SYSTEM EVALUATION

7.1 APPENDIX 3 Performance Evaluation

7.1.1 APPENDIX 3 Validation of the Simulator

7.1.2 APPENDIX 3 Simulations for Automatic System Performance Demonstration

7.1.3 APPENDIX 3 Flight Test Performance Demonstration

7.1.4 APPENDIX 3 Demonstration of Approach and Automatic Landing with an Inoperative Engine

7.2 APPENDIX 3 Safety Assessment

8 APPENDIX 3 AIRBORNE SYSTEMS

8.1 APPENDIX 3 Automatic Flight Control Systems

8.2 APPENDIX 3 Autothrottle Systems

8.3 APPENDIX 3 Head Up Guidance

8.4 APPENDIX 3 Hybrid HUD/Autoland System [PoC]

8.4.1 APPENDIX 3 Hybrid HUD/Autoland System Fail Operational Equivalency Concept

8.4.2 APPENDIX 3 Hybrid System Go Around Capability

8.4.3 APPENDIX 3 Hybrid System Transition From Automatic to Manual Flight

8.4.4 APPENDIX 3 Hybrid System Pilot Not Flying (PNF)

8.5 APPENDIX 3 Satellite Based Landing Systems [PoC]

8.5.1 APPENDIX 3 Flight Path Definition

8.5.2 APPENDIX 3 Aircraft Database

8.5.3 APPENDIX 3 Differential Augmentation

8.5.4 APPENDIX 3 Datalink

8.6 APPENDIX 3 Enhanced Vision Systems [PoC]

9 APPENDIX 3 AIRPLANE FLIGHT MANUAL

APPENDIX 4 WIND MODEL FOR APPROACH AND LANDING SIMULATION
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APPENDIX 5 [RESERVED]

APPENDIX 6 AFM PROVISIONS AND SAMPLE AFM WORDING

6.1 APPENDIX 6 Example Provision – AFM “Certificate Limitation” Section

6.2 APPENDIX 6 Example Provision - AFM “Normal Procedures” or “Normal Operation”

[Typical Aircraft Type with Fail Operational and Fail Passive FGS]

6.3 APPENDIX 6 Example Provision - AFM “Normal Procedures” or “Normal Operation”

[Typical Aircraft Type with Fail Passive FGS Capability]

APPENDIX 7 STANDARD OPERATIONS SPECIFICATIONS - GENERAL

APPENDIX 7 OPERATIONS SPECIFICATIONS - GENERAL

APPENDIX 7 Para. A002

APPENDIX 7 Para. C051

APPENDIX 7 Para. C055

APPENDIX 7 Para. C056

APPENDIX 7 Para. C060

APPENDIX 7 Para. C078

APPENDIX 8 IRREGULAR TERRAIN ASSESSMENT

APPENDIX 9 TAKEOFF SYSTEM PERFORMANCE AFTER LIFTOFF
07/13/99 AC 120-28D

Page 1

1. PURPOSE. This advisory circular (AC) provides an acceptable means, but not the only means, for

obtaining and maintaining approval of operations in Category III Landing Weather Minima and low

visibility takeoff including the installation and approval of associated airborne systems. This AC is

applicable to Title 14 of the Code of Federal Regulations (14 CFR) part 121, 135 and 125 operators.

Certain aspects of this AC are applicable to 14 CFR part 129 operators. Many of the principles,

concepts and procedures described also may apply to 14 CFR part 91 operations and are

recommended for use by those operators when applicable. Mandatory terms used in this AC such as

"shall" or "must" are used only in the sense of ensuring applicability of these particular methods of

compliance when the acceptable means of compliance described herein is used. This AC does not

change, add or delete regulatory requirements or authorize deviations from regulatory requirements.

CANCELLATION. AC 120-28C, dated March 9, 1984, and AC 20-57A dated January 12, 1971, are

canceled.

2. RELATED REFERENCES AND DEFINITIONS.

2.1. Related References. Title 14 of the Code of Federal Regulations (14 CFR) part 23,

section 23.1309; part 25, sections 25.1309, 25.1322, 25.1581, and 25.1583; part 91,

sections 91.175 and 91.189; part 121, sections 121.579, and 121.651; part 125, sections 125.379,

and 125.381; part 129, section 129.11; and part 135, section 135.225.

Unless a specific reference is made to a particular version of a rule or AC, current editions of the

following AC’s should be used:

AC 23.1309-1, Equipment, Systems, and Installation in Part 23 Airplanes

AC 25-7A, Flight Test Guide for Certification of Transport Category Airplanes

AC 25.1309-1, System Design Analysis

AC 120-29, Criteria for Approving Category I and Category II Landing Minima for 14 CFR

Part 121 Operators

Standard Operations Specifications Parts A and C,

FAA Order 8400.8, Procedures for Approval of Facilities for FAR Part 121 and Part 135 Category

III Operations

FAA Order 8400.10, Air Transportation Operations Inspector’s Handbook

2.2. Definitions. A comprehensive set of definitions pertinent to Category III approach and landing

and low visibility takeoff is included in Appendix 1.
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Within this AC, Runway Visual Range (RVR) values are specified in units of feet (ft.) unless otherwise

noted (e.g., meters (m)).

Where visibility minima are stated in both feet and meters (e.g., RVR300 (75m)) using values other than

those identified as "equivalent" in standard operations specifications, it is intended that the RVR value in

feet apply to minima specified in feet, and the value in meters apply in states specifying their minima in

meters.

Minima typically used for low visibility operations including a minima conversion table where applicable

are provided in the operations specifications shown in Appendix 7.

In this AC, where the term “RNP Level” is used, it may be considered to be equivalent to the term

“RNP Type” typically used in some current ICAO and other authority references. The term “RNP

Level” is used in the U.S. to match various RNP approval documents (e.g., AFM’s) already in

widespread use, and to reserve use of the term “RNP Type” for future anticipated RNP applications.

3. BACKGROUND.

3.1. Major Changes Addressed in this Revision. This AC includes additional Category III criteria

or revised Category III criteria for use in conjunction with Head-up Displays, satellite navigation

systems, low visibility takeoff guidance systems, Wide-body Fail Passive operations and use of

Category III during certain engine inoperative operations.

This revision also updates and incorporates provisions of the former AC 20-57 into AC 120-28, since

provisions of the former AC 20-57 are directly related to and dependent on criteria provided in this

AC.

This revision incorporates changes resulting from the first steps toward international all weather

operations (AWO) criteria harmonization taken by the Federal Aviation Administration (FAA), the

European Joint Aviation Authorities (JAA), and several other regulatory authorities. Subsequent

revisions of this AC are planned as additional all weather operations harmonization items (AHI) are

agreed and completed by FAA and JAA, or internationally.

3.2. Relationship of Operational Authorizations for Category III and Airborne System

Demonstrations. Takeoff and landing weather minima are approved through applicable operating

rules, use of approved instrument procedures and issuance of operations specifications. Airworthiness

demonstration of airborne equipment and systems is usually accomplished in support of operational

authorizations on a one time basis at the time of Type Certification (TC) or Supplemental Type

Certification (STC). Since operating rules continuously apply over time and may change after

airworthiness demonstrations are conducted, or may be updated consistent with safety experience,

additional Category III credit or constraints may apply to operators or aircraft as necessary for safe

operations. Airworthiness demonstrations are based on the particular operational and airworthiness

criteria in effect at the time a type design certification basis is established for a particular TC or STC.
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Subsequent operational authorizations may constrain capabilities originally demonstrated based on

current operational regulatory policy and experience. The main body of this AC contains criteria related

to operational approval and Appendix 2 and Appendix 3 are the primary source of airworthiness

criteria. Nothing in this AC is intended to preclude an operator from proposing and demonstrating to

the FAA the ability to operate to Category III minima with a different equipment configuration; or

alternatively to an RVR minima lower than that presently described in this document.

3.3. Applicable Criteria. AC 120-28C, dated March 9, 1984, and AC 20-57A dated

January 12, 1971 are canceled. Except as described below, new airworthiness demonstrations or

operational authorizations should use criteria of AC 120-28D. Airworthiness demonstrations may use

equivalent JAA criteria where agreed by FAA through the FAA/JAA criteria harmonization process.

In general, the provisions of the main body of this AC outline concepts, objectives, and provisions

necessary for operators. The appendices contain definitions, abbreviations, airworthiness demonstration

provisions typically applied in conjunction with type certification, technical information necessary for

airworthiness or operational assessments (e.g., atmospheric/wind models, obstacle clearance criteria) and

examples of operational authorizations (e.g., sample Operations-Specifications (OpSpecs)). Certain

criteria related to airworthiness assessment are included in the main body of the AC primarily to address

the status and eligibility of previously certificated in-service aircraft for current authorizations (e.g., status of

service bulletin compliance for continued or new authorizations, demonstration provisions applicable to "inservice" aircraft).

Operators electing to comply with this AC's revised criteria may receive the applicable additional

credit(s). Aircraft manufacturers, operators or modifiers may elect to demonstrate that their aircraft

meet the revised criteria to seek additional credit for any particular operation (e.g., HUD installation) or

for all operations addressed by this AC (e.g., incorporation of a general compliance statement related to

AC 120-28D, instead of reference to the former canceled criteria of AC 120-28C). However, aircraft

demonstrated to earlier criteria may continue to be approved for Category III operations in accordance

with that earlier criteria, and applicants may continue to make reference to the fact that an earlier

demonstration was based on that previous criteria

(e.g., in the AFM). Aircraft manufacturers, modifiers or operators seeking authorization provided for

only in this AC must, however, use applicable criteria of this AC (e.g., for RNP based missed approach

obstacle criteria, meet pertinent provisions of Appendix 9). To get a particular authorization cited by

this AC, the operator need only meet the provision or provisions applicable (e.g., RVR600 fail passive

landing minima may be authorized per 4.3.8 for presently authorized airborne systems meeting previous

criteria without regard to Appendix 3 criteria).

4. OPERATIONAL CONCEPTS.

4.1. Classification and Applicability of Minima. Landing minima are generally classified by

Category I, Category II and Category III (e.g., see ICAO Annex 6 references, and the associated
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ICAO Manual of All Weather Operations DOC 9360/AN910, 2nd Edition, 1991). AC 120-29 (as

amended) addresses Category I and II. This AC addresses Category III.

Takeoff minima are usually classified by RVR or meteorological visibility, and other factors (e.g., aircraft

characteristics).

Although a wide variety of normal and non-normal situations are considered in the design and approval

of systems used for Category III, Category III minima are primarily intended to apply to normal

operations.

For non-normal operations, flightcrews are expected to take the safest course of action appropriate for

the situation, including consideration of normal landing weather minima. When aircraft systems have been

demonstrated to account for certain non-normal configurations (e.g., an approach with an engine

inoperative) flightcrew may take into account this information in assessing the safest course of action.

4.2. Takeoff. Takeoff minimums are included in standard operations specifications. This AC

addresses criteria for takeoff in low visibility conditions where additional aircraft equipment is provided

to assist the pilot in a low visibility takeoff, or is required to assure safe operations when using minima

below values acceptable for exclusive use of visual reference.

Standard OpSpecs list minima acceptable to FAA for manual control based exclusively on visual

reference.

Authorization of takeoff minima below the level supported by use of visual reference alone requires use

of a guidance system which has been demonstrated to provide an acceptable level of performance and

satisfactory workload for the minima approved, with or without use of visual reference. The

performance and workload assessment of such a system must have considered any compensation that

may be introduced by the pilot for particular guidance system characteristics (e.g., coping with a slight

localizer signal offset during initial runway alignment) or concurrent pilot use of the guidance system with

limited or patchy visual references.

Systems intended to be used at or above the minima authorized for visual reference alone (e.g., as a

supplement to manual control) may be used if demonstrated to be:

1) Safe in normal use, and

2) If there is no unacceptable increase in pilot workload or significant adverse effect on crew

coordination, and

3) If the system is unlikely to introduce a significant hazard if a failure or degradation of the system itself

occurs, and
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4) If the system is unlikely to introduce a significant additional hazard if other potential failures in the

aircraft occur (e.g., engine failure, electrical component failure), and

5) A failure or anomaly in a NAVAID(s) used does not introduce a significant hazard.

Authorized minima for such systems may be no lower than that specified for manual control using visual

reference alone.

If low visibility takeoff operations are predicated on the use of RNP, then the provisions applicable to

RNP apply only following liftoff, after passing 35 ft. above the published elevation of the runway.

A proof of concept demonstration is necessary for initial authorization of takeoff minima less than

RVR300 ft./75m.

Criteria for demonstration of systems eligible for takeoff minima below the level supported by use of visual

reference alone are found in section 5.1.3 for operational authorization or Appendix 2 for systems

proposed for airworthiness demonstration.

4.3. Landing.

4.3.1. Concepts and Objectives. Category III landing minima are classified as Category IIIa,

Category IIIb or Category IIIc. Definitions of these categories are provided in Appendix 1. Visual

conditions encountered in Category III operations range from visual references being adequate for

manual control during rollout (e.g., Category IIIa) to visual references being inadequate even for taxi

operations without special visual reference enhancements or suitable synthetic references. For any

Category III operation, the airplane and external system requirements established (e.g., position fixing)

should be compatible with any visual reference requirements that are specified.

Category III operations may be conducted manually using Flight Guidance Displays, or automatically

using approved autoland system or with Hybrid Systems which employ both automatic and flight guidance

elements. If the particular Flight Guidance Display depicts flight director or other command guidance it

may be approved in accordance with this AC, or equivalent. Situational Flight Guidance Displays may be

used if the Proof of Concept (PoC) is satisfactorily demonstrated. When an automatic system is to be the

primary means of control the use of that system should not require pilot intervention. The means for crew

intervention must be provided, however, in the unlikely event the pilot detects or strongly suspects

inadequate system performance (e.g., the pilot determines that an automatic landing cannot be

accomplished within the touchdown zone). If a Hybrid system is employed, then the primary mode of

operation must be automatic to touchdown, with manual control used only as an alternate means to

complete the operation.

To be approved for Category III operations, the airplane and its associated systems should be shown to

be capable of safely completing an approach, touchdown, and rollout and permitting a safe go-around

from any altitude to touchdown following any failure condition not shown to be extremely improbable.
AC 120-28D 07/13/99

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Cockpit design, instrumentation, annunciations and warning systems, should be adequate in combination

to assure that the pilot can verify that the aircraft should touch down within the touchdown zone and safely

rollout if the controlling visibility is reported at or above applicable minima. Systems based on automatic

control to touchdown, or touchdown and rollout and manually flown flight guidance system (e.g., HUD),

have been approved by FAA. Other concepts may be acceptable if Proof of Concept [PoC] testing can

demonstrate an equivalent or greater level of safety as presently specified for approval of automatic

systems (e.g., hybrid systems or vision enhancement systems).

To be approved for Category III operations, the airplane and its associated systems should be shown to

be able to perform to the necessary level of accuracy, integrity, and availability. This is typically shown

initially during airworthiness demonstration, is confirmed during the operational authorization process,

and is monitored by the operator on a continuing basis.

Category III operations are predicated on meeting requirements for Category II, or equivalent, for that

portion of the approach prior to 100' HAT (see the current version of AC 120-29 for approval of

Category II).

If Category III operations are predicated on the use of RNP, then the provisions of this AC or any

subsequent current version of AC120-29A, or other suitable FAA criteria for application of RNP are

considered to be acceptable to apply to definition of any instrument approach procedure segment down

to 100 ft. HAT.

Below 100 ft. HAT, the provisions of this or any subsequent version of AC120-28 are considered to

be the applicable criteria to assure the necessary performance for landing, flare and rollout.

For a go-around and missed approach from DA(H), Alert Height (AH), or the end of the touchdown

zone for a rejected landing, RNP provisions may be applied from the point of initiation of a go-around

to completion of the applicable missed approach procedure, in accordance with provisions of this

version of AC 120-29, any subsequent current version, or any other RNP criteria found acceptable to

the FAA.

4.3.2. Fail Operational Category III Operations. A Fail Operational System is a system which after

failure of any single component, is capable of completing an approach, flare and touchdown, or

approach, flare, touchdown and rollout by using the remaining operating elements of the Fail Operational

system. The failure effects of single components of the system, airplane or equipment external to the

airplane which could have an effect on touchdown or rollout performance must be considered when

evaluating Fail Operational systems. Fail Operational systems may be used to touchdown for Category

IIIa (e.g., without a rollout system) or Category IIIb through rollout to a full stop. Use of a failoperational system to touchdown in conjunction with a rollout system that is not fail-operational is

acceptable as long as a suitable minimum RVR is specified in the operations specifications, for rollout.
07/13/99 AC 120-28D

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This AC contains criteria for approval of minima as low as RVR150 using a fail-operational system for

landing and rollout. Approval of minima less than RVR150 would require a proof of concept [PoC]

demonstration.

Note: A landing system is considered to include each of the elements in the aircraft which

are necessary to perform the landing and rollout function (e.g., flight control, hydraulic

system(s), electrical system(s), sensors).

The required redundancy may be provided by multiple automatic landing systems, by multiple automatic

landing and rollout systems, by redundant manual flight guidance systems, or by suitably redundant

hybrid systems.

The reliability and performance of the required operational systems should be such that continued safe

operation to landing, or landing and rollout, can be achieved following any failure condition occurring

below the Alert Height that is not shown to be extremely improbable. Systems identified below and in

4.3.3 through sections 4.3.8, or equivalent, are considered to meet the intent of this provision.

Failure conditions which result in the loss or disconnect of all the redundant landing, or landing and

rollout systems, occurring below the Alert Height, are permissible if the occurrence of these failure

conditions is extremely remote and the loss or disconnect is accompanied by acceptable warning

indications for the pilots. Airplanes which are demonstrated to meet the airworthiness assessments of

Appendix 3 for fail operational systems are considered to meet these reliability and performance criteria.

The following are typical arrangements which may be acceptable for Fail Operational Systems:

1. Two or more monitored fail passive autopilots or integrated autopilot flight director systems each

with dual channels making up an automatic fail operational system designed so that at least one autoflight

system remains operative after the failure of one system, and the failed system is not used or cannot

cause unacceptable autoflight system performance.

Note: Following a failure with this configuration, it is not intended that a landing be

continued with flight director alone, unless a successful Proof of Concept

demonstration has been completed.

2. Three autopilots or integrated autopilot flight director systems designed so that at least two

remain operative after failure to permit comparison and provide necessary monitoring and protection

while continuing to a landing.

3. A monitored fail passive automatic flight control system with automatic landing capability to

touchdown and rollout, if applicable, plus an independent and adequately failure protected manual flight

guidance system, suitable for landing and rollout with guidance provided for the flying pilot and

monitoring displays for the non-flying pilot. A proof of concept demonstration would be necessary for

this arrangement.
AC 120-28D 07/13/99

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4. Two independent and adequately monitored manual flight guidance systems with independent

displays for the pilot flying and the pilot not flying, each capable of supporting a landing and rollout. A

proof of concept demonstration would be necessary for this arrangement.

Aircraft meeting fail-operational requirements of Appendix 3 of this AC, or equivalent, for landing and

rollout may be authorized for fail-operational Category III to the lowest currently applicable minima

specified in Operations-Specifications for this type of system. As of the publication of this AC, the

lowest authorized minima for U.S. operators are Touchdown, Mid, and Rollout RVR of 300ft within the

U.S., or 75m internationally.

Aircraft previously demonstrated to meet acceptable fail-operational criteria of earlier AC’s or alternate

criteria (e.g., suitable JAR criteria) may receive additional credit beyond those already authorized, as

specified in provisions of this AC, through appropriate showing of compliance with applicable

operational provisions of this AC, and subsequent amendment of applicable operations specifications.

An example of aircraft in this category are those B767 or B757 aircraft having statements in the FAA

approved AFM indicating they met all fail-op rollout provisions of AC 120-28B or AC 120-28C,

except for certain rollout disconnect provisions. Since criteria of AC 120-28D are now revised to

alternately address this condition, these aircraft are considered eligible to fully meet Appendix 3

provisions for fail-operational rollout and may be operationally authorized for landing minima

accordingly (also see 4.3.8).

Aircraft with a fail operational landing system but without a rollout system, that were originally approved

in accordance with AC 120-28, AC 120-28A, AC 120-28B or AC 120-28C, may typically be

approved for minima not less than Touchdown Zone, Mid and Rollout RVR600. Eligibility for RVR600

requires compliance with appropriate current service bulletins in accordance with the manufacturer’s

recommendations, and a determination by FAA that “in-service” operational performance of the system

is acceptable.

Aircraft with a fail operational landing system and a rollout system, or a fail operational landing system

and a fail passive rollout system originally approved in accordance with FAA “Special Conditions” for a

rollout system, or criteria of AC120-28, AC120-28A, or AC120-28B are now considered to have

rollout capability equivalent to fail operational and may typically be approved for minima not less than

Touchdown Zone, Mid, and Rollout RVR300. Current models in this group found acceptable include

the L1011, A300, DC10-30, certain DC10-10s or DC10-40s with suitably upgraded avionics

equipment equivalent to currently FAA approved DC10-10s or -30s, and late model B747-200 or -

300 aircraft with appropriate versions of the triple channel SPZ-1 autopilot and a rollout system. For

these aircraft, appropriate current service bulletin compliance should be reviewed and completed, and

line operational performance of the system must be shown to be acceptable. However it is important to

note that, as with other aircraft types, Category III authorization for some of these aircraft may be

restricted to certain runway facilities since landing or rollout performance may not necessarily be
07/13/99 AC 120-28D

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acceptable due to site specific irregular underlying approach terrain, touchdown zone slope, or ILS

beam characteristics.

4.3.3. Alert Height. Fail-operational Category III is based on use of an Alert Height (see Appendix

I). An Alert Height is the height above a runway based on characteristics of the airplane and its Fail

Operational System, above which a Category III approach must be discontinued and a missed

approach initiated if a failure occurred in one of the redundant parts of the flight control or related

aircraft systems, or if a failure occurred in any one of the relevant ground systems. Use of an Alert

Height is consistent with the design philosophy which requires that an aircraft be capable of safely

completing a touchdown and rollout (if applicable) following a failure occurring after passing the point at

which the Alert Height is specified.

Operational Alert Heights must always be equal to or lower than that specified in the airworthiness

demonstration, and may be specified at or below 200 ft. HAT. The Alert Height is specified by an

operator of an aircraft and approved by the FAA. The operational Alert Height used must be

consistent with the aircraft design, training, ground facilities, and other factors pertinent to the air carriers

operation. Typically a minimum usable operational alert height is 50’HAT. However lower Alert

Heights may be approved if there is an appropriate reason to do so (e.g., for certain types of hybrid

systems).

Airworthiness demonstration of an Alert Height is as specified in Appendix 3. In order to assure the

necessary reliability of aircraft systems, airworthiness demonstrations of Alert Height should be from an

altitude of at least 200 ft. above the touchdown zone elevation.

4.3.4. Fail Passive Category III Operations. A Fail Passive System is a system which in the event of

a failure, causes no significant deviation of aircraft flight path or attitude. The capability to continue the

operation may be lost and an alternate course of action (e.g., a missed approach) may be required. A

fail-passive system is the minimum capability system acceptable for Category III operation with a Decision

Height not less than 50 ft. HAT.

Fail Passive Approach Operations are conducted with a decision height not lower than 50 ft., and are

limited to RVR values which provide suitable visual reference to address normal operations as well as

failure contingencies. Since a Fail Passive Category III system does not necessarily provide sufficient

redundancy to successfully continue the approach and landing to touchdown following any failure in the

flight control system not shown to be extremely remote, a DH is specified. A DH is established to

assure that prior to passing that point the pilot is able to determine that adequate visual reference exists

to allow verification that the aircraft should touchdown in the touchdown zone. If this visual reference is

not established prior to passing DH, a missed approach must be initiated. After passing DH, a missed

approach will also be initiated if visual cues are lost, or a reduction in visual cues occurs which prevents

the pilot from continuing to verify the aircraft is in a position which will permit a landing in the touchdown

zone. In the event of a failure of the airborne system at any point in the approach to touchdown, a
AC 120-28D 07/13/99

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missed approach is required. However, this provision does not preclude a pilot's authority to continue

an approach if continuation of an approach is considered by the pilot to be a safer course of action.

Such a failure however, does not preclude continuation to a Category I or Category II minima if the

necessary remaining elements of the aircraft system are operational and if the crew qualification

addresses necessary action to continue such an approach are met. Any adjustments to approach

minima or procedures made on final approach should be completed at a safe altitude (e.g., above 500

ft. HAT).

The need to initiate a go-around below 100 ft. AGL due to an airplane failure condition should be

infrequent. In addition, an aircraft using a Fail Passive system for Category III should be shown to

provide the capability to touch down in the touchdown zone or to complete a safe manual or automatic

go-around from any altitude to touchdown following any failure condition not shown to be extremely

improbable.

Typical arrangements which may be used to meet the requirements for Category III fail passive

operations using a 50 ft. Decision Height include the following:

1. A single monitored automatic flight control system with automatic landing capability.

2. A fail operational automatic flight control system with automatic landing which has reverted to a

Fail Passive configuration or has been dispatched in a fail-passive configuration.

3. A monitored flight guidance system (e.g., HUD) designed for manual control by the pilot flying,

and for monitoring by the pilot not flying. Aircraft intended for Fail Passive Category III operations

should have aircraft systems which meet the criteria specified in Appendix 3. Aircraft previously

demonstrated to meet earlier Fail Passive criteria may continue to operate using Category III minima in

accordance with approved operation specifications.

4.3.5. Decision Altitude (Height). For Category II and certain Category III procedures (e.g., when

using a Fail-Passive landing system) a Decision Height (or an equivalent IM position fix) is used as the

controlling minima. The "Altitude" value specified is considered as advisory. The altitude value is available

for cross reference. Use of a barometrically referenced DA for Category III is not currently authorized for

part 121, 129 or 135 operations at U.S. facilities.

A Decision Height is applied to all Fail Passive operations and is specified at certain locations where fail

operational minima is authorized. For Category III, a Decision Height is usually based on a specified

radio altitude above terrain on the final approach or touchdown zone. The Decision Height is

established to assure that prior to passing that point the pilot is able to determine that adequate visual

reference exists to allow verification that the aircraft should touch down in the touchdown zone.

For Category I, a DA(H) is specified as the minimum altitude in an approach by which a missed

approach must be initiated if the required visual reference to continue the approach has not been
07/13/99 AC 120-28D

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established. The "Altitude" value is typically measured by a barometric altimeter or equivalent (e.g.,

Middle Marker) and is the determining factor for minima for Category I Instrument Approach

Procedures. The "Height" value specified in parenthesis is typically a radio altitude equivalent height

above the touchdown zone (HAT) used only for advisory reference and does not necessarily reflect

actual height above underlying terrain. The DA element of a DA(H) is applicable to Category III only in

the event that an approach is considered to revert to Category I or Category II minima following

airborne equipment failure, ground facility status, or other similar condition permitting an approach to be

conducted to pertinent Category I or II minima.

4.3.6. Go-Around Safety. An aircraft approved for Category III should be capable of safely

executing a go-around from any point in an approach prior to touchdown with the aircraft in a normal

configuration, or specified non-normal configuration (e.g., engine out if applicable). It is necessary to

provide for go-around due to Air Traffic Services contingencies, rejected landings, loss of visual

reference, or missed approaches due to other reasons. The evaluation of this capability is based on

normal, or specified non-normal, Category III operations at the lowest controlling RVR authorized and

should account for factors related to geometric limitations during the transition to go around, limited

visual cues, auto-pilot mode switching and other pertinent factors. For aircraft in which a go-around

from a very low altitude may result in an inadvertent touchdown, the safety of such a procedure should

be established considering its effect on related systems, such as operation of auto spoilers, automatic

braking systems, autopilot mode switching, autothrottle mode, reverse thrust initiation and other systems

associated with, or affected by, a low altitude go-around.

Except for failure conditions shown to be extremely improbable, a safe go-around must be possible

from any point on the approach to touchdown.

If an automatic go-around capability is provided, it should be demonstrated that a go-around can be

safely initiated and completed from any altitude to touchdown. If the automatic go-around mode can be

engaged at or after touchdown, it should be shown to be safe. The ability to initiate an automatic goaround at or after touchdown is not required.

4.3.7. Category IIIa. In accordance with ICAO definitions of Category III, Category IIIa operations

may be conducted with either Fail Operational or Fail Passive systems. The lowest approvable landing

minima for Category IIIa is RVR700 or a foreign equivalent of 200 meters.

Note: For certain Category III operations using fail passive systems that were formerly

limited to RVR700, but now are eligible for authorization to RVR600, see paragraph

4.3.8 (Most Category III operations authorized for RVR700 prior to issuance of this AC

are now eligible for authorization to RVR600, upon request of the operator for issuance

of a revision to that operator's pertinent OpSpecs).

Category IIIa operations with fail passive systems are conducted using a 50 ft. Decision Height.
AC 120-28D 07/13/99

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Category IIIa operations using a fail operational system with a rollout control system are generally

conducted using an Alert Height, and not a Decision Height. Visual reference is not a specific

requirement for continuation of the approach or touchdown.

Category IIIa operations using a fail operational system without a rollout control system installed require

establishment of suitable visual reference with the touchdown zone prior to touchdown.

For any of the above systems there should be a sufficient combination of information from flight

instruments, annunciations, and alerting systems to assure that the pilot can verify that the aircraft should

touch down within the touchdown zone, and safely initiate rollout.

Unless otherwise specified by FAA, aircraft having operation specifications authorizing RVR700 as of

the effective date of this AC, may continue to use those minima without additional demonstration.

Aircraft demonstrated to meet airworthiness provisions of AC 120-28B or AC 120-28C for Fail

Passive systems remain eligible for any previously approved operational authorization under provisions

of this AC and do not require additional airworthiness demonstration. Aircraft previously having

completed an airworthiness demonstration in accordance with AC 120-28C remain eligible for any

operational authorization that was permitted by AC 120-28C.

Aircraft demonstrated to meet airworthiness criteria prior to AC 120-28B, and not currently authorized

in operations specifications for Category III may be approved for new Fail Passive Category III

operations on a case-by-case basis depending on facilities to be used, service bulletin compliance status

and other relevant safety factors.

Aircraft, including wide body aircraft such as the DC-10, L1011 and B 747, which are authorized for

fail-operational Category III, but have not been demonstrated to meet the provisions for Fail Passive

systems shown in Appendix 3, may be approved for Fail Passive operations with landing minima limited

to RVR1000 provided the following criteria are met:

1. The aircraft must be shown to be in compliance with relevant service bulletins for the applicable

flight control system and displays.

2. An auto throttle system must be installed and operational.

3. The system must be shown to provide reliable auto land performance in line operations.

4. A demonstration using a simulator or aircraft must be completed for that operator and aircraft

type, showing that the system and procedures applicable to Fail Passive operations can be practically

applied for that air carrier’s operation.
07/13/99 AC 120-28D

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Wide body aircraft types not previously authorized or currently authorized by FAA to use minima less

than RVR1000 based on a fail passive system must meet the airworthiness requirements of Appendix 3

or equivalent for any new authorization of minima less than RVR1000.

New aircraft types or derivative aircraft with new flight control system designs should be demonstrated

in accordance with Appendix 3 for Fail Passive systems, or equivalent requirements, if fail passive

authorization is sought.

4.3.8. Category IIIb. Category IIIb operations are usually conducted with fail operational systems.

Fail passive landing systems may be used, but are limited to Category IIIb minima not less than

touchdown zone RVR600 (175 m). Airborne systems used for Category IIIb authorized for landing

below touchdown zone RVR600 (175 m) must include either a manual flight guidance or automatic

rollout or control system for lateral steering which provides the means to control the aircraft until the

aircraft slows to a safe taxi speed. Category IIIb operations based on fail operational systems require

the use of systems which after passing Alert Height, are capable of the safe completion of the approach,

touchdown, and rollout, following any failure conditions not shown to be extremely remote. When fail

operational systems are used, they do not necessarily require that operating procedures specify that the

approach must necessarily be continued after a failure.

Category IIIb operations based on fail passive landing systems meeting provisions of Appendix 3 of this

AC, or equivalent, must use a decision height not less than 50 ft. HAT.

For Category IIIb operations based on fail operational systems, the availability of visual reference is not

a specific requirement for continuation of an approach to touchdown. The design of flight instrument

systems, annunciations, and alerting systems should be adequate to assure that the pilot can verify the

aircraft should touch down within the touchdown zone, and rollout.

Category IIIb operations may be conducted to a touchdown zone RVR and relevant mid or rollout

RVR not less than 600 ft. with a fail operational or fail passive landing system without a rollout control

system.

Category IIIb operations may be conducted to a touchdown zone RVR of not less than 600 ft. and an

relevant mid or rollout RVR not less than RVR400 with a fail operational or fail passive landing system

and with any FAA approved rollout control system.

Category IIIb operations may be conducted to a touchdown zone, and relevant mid, and rollout RVR

minima not lower than RVR400 (125 m) when using a fail operational landing system and a rollout

control system shown to meet Fail Passive criteria of Appendix 3 (or earlier FAA criteria applicable to

a rollout system).
AC 120-28D 07/13/99

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Category IIIb operations may be conducted to a touchdown zone RVR, and relevant mid, and rollout

RVR minima not less than RVR150 (50 meters) with a fail operational landing system and a rollout

control systems shown to meet the Fail Operational criteria of Appendix 3, or earlier equivalent criteria.

See NOTE below for criteria, and Section 4.3.2 above for examples of various aircraft types, systems,

and minima which may be authorized.

NOTE: Since amended criteria is specified for fail operational rollout control systems in

Appendix 3 of this circular, certain systems previously certificated using earlier criteria of

AC120-28C or AC120-28B that at the time of certification were not considered fail

operational due to certain conditions that were noted in the AFM as exceptions, but now

are considered to meet fail operational criteria, may now be considered as fail operational

for the purpose of authorizations under this paragraph.

Accordingly, systems considered to be eligible for this credit are those systems which

otherwise previously met all provisions for a fail operational rollout control system as

described in Appendix 3 of AC120-28C (or earlier AC 120-28A or B equivalent) except

for provisions related to inadvertent control wheel autopilot disconnect and level of

redundancy required for nosewheel steering function. Each of these provisions are now

revised in Appendix 3.

Operators seeking additional allowable credit for these newly re-classified fail-operational

rollout control systems may apply for corresponding minima adjustment through amended

operations specifications. "Relevant" or "applicable" mid or rollout RVR is considered to be

any transmissiometer report (or equivalent instrumentally derived RVR measurement)

considered to be covering a portion of the runway where the aircraft is operating at a speed

above a safe taxi speed.

A summary of the minima that may now be authorized based on the above criteria are shown below in table

4.3.8-1.

Landing System Type Rollout System Type TDZ RVR (ft)** Mid RVR (ft)** Rollout RVR (ft)**

Fail Op or Fail Passive* No Rollout system 600 600 600

Fail Op or Fail Passive* Any FAA Approved

Rollout System

600 400 400

Fail Op* Fail Passive* 400 400 400

Fail Op* Fail Op* 150 150 150

Lowest Minima Authorized for Fail Operational or Fail Passive Landing Systems, or

Landing and Rollout Systems

Table 4.3.8 -1

Table 4.3.8-1 Notes:
07/13/99 AC 120-28D

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* Note: Fail Op denotes a Fail Operational Flight Guidance System

Fail Passive denotes Fail Passive Flight Guidance System

** Note: RVR values are shown in U.S. facility units of feet and as Touchdown zone,

Mid, and Rollout RVR values, but corresponding metric values or other designated

RVR reporting locations may be applied internationally, if acceptable to the State of the

Aerodrome.

Equivalent minima may be specified for systems demonstrated to meet earlier airworthiness criteria of

AC 120-28B or AC 120-28C. Credit for systems demonstrated prior to AC 120-28B will be as

designated in approved operations specifications or as designated by AFS-400 for new Category III

applications using such aircraft.

4.3.9. Runway Field-Length.

a. The Runway Field-Length for Category III is as specified by section 121.195 for a wet runway,

if each of the following conditions are met:

1. Anti-skid systems are operative (if installed for the aircraft type).

2. The runway surface braking action is expected to be at least "fair" or better (or equivalent

Runway Condition Reading, James Brake Devise, or Tapley reading).

In the event that either of the above conditions are not met, the factor to be applied to the

section 121.195b distance is 1.3, unless otherwise demonstrated to the FAA that a factor less than 1.3

is acceptable (e.g., due to other factors, such as the required use of an auto brake system).

b. Once airborne, additional consideration of Category III landing field length by the flightcrew is not

required for normal operations. In the event of un-forecast adverse weather or if failures occur, the crew

and aircraft dispatcher should consider any adverse consequences that may result from a decision to make a

Category III landing (e.g., braking action reports). Category III operations should not normally be

conducted with braking action less than "fair".

c. When auto brake systems are used for Category III, information must be available to the

flightcrew to assist in making the proper selection of a suitable auto brake setting consistent with the field

length available for landing and the runway condition, including braking action.

4.3.10. Landing System Sensors (NAVAID’s) and Aircraft Position Determination. Various

landing system sensors (NAVAID’s) or combinations of sensors may be used to provide the necessary

position fixing capability to support authorization of Category III landing weather minima. While certain

navigation sensors (NAVAID’s) are installed and classified primarily based on landing operations, the

sensors described in this section may also be used for takeoff, missed approach, or other operations

(e.g., RNAV position determination). Regardless of the sensors, NAVAID’s, or combination of
AC 120-28D 07/13/99

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NAVAID’s used, the NAVAID’s and sensors must provide coverage for the intended flight path and

for anticipated displacements from that flight path for normal operations, rare normal operations (e.g.,

winds and wind gradients), and for specified non-normal operations where applicable (e.g., "engine-out

go-around" flight path). In addition, Category III authorizations should be consistent with the provisions

or characteristics for specific sensors listed below in 4.3.10.1 through 4.3.10.3 unless otherwise

accepted or approved by FAA.

4.3.10.1. Instrument Landing System (ILS). The ILS provides a reference signal aligned with the

runway centerline and deviation signals when the airplane is displaced left or right of the extended

runway centerline. The linear coverage area for this signal is approximately 3 degrees either side of the

extended runway centerline from a point emanating at the far end of the runway. The ILS also provides

a vertical flight path (nominally 3 degree descent angle) to a point in the landing zone of the runway. The

vertical coverage is approximately 0.7 degrees on either side of the vertical reference path. ILS

characteristics should be considered as defined in ICAO Annex 10, unless otherwise specified by FAA.

U.S. ILS systems are classified by Type, as defined in FAA Order 6750.24 as amended (e.g., II/D/2).

4.3.10.2. Microwave Landing System (MLS). The MLS provides a reference signal aligned with

the runway centerline and deviation signals when the airplane is left or right of the extended centerline.

The linear coverage area is approximately 40 degrees either side of the extended runway centerline

emanating from a point at the far end of the runway. The MLS provides a vertical flight path to the

runway similar to ILS. MLS characteristics should be considered as defined in ICAO Annex 10, unless

otherwise specified by FAA. U.S. MLS systems are classified by Type, similar to ILS.

4.3.10.3. GPS/GNSS Landing System (GLS). GLS is a landing systems based upon the Global

Navigation Satellite System (GNSS). For Category III operations the landing system typically includes

a local area differential augmentation system in the vicinity of the runway for which a Category III

procedure is specified. The local area system may serve one or more runways, or nearby airports,

depending on its classification for each particular runway. The classification of a GLS service may be

different for different runway ends (e.g., III/E/3 for Runways 14L and 14R, but I/D/1 for RW 22L).

Desired path, centerline, and deviation signals as applicable, are computed by airborne avionics. The

coverage area for GLS is typically at least within a 25 mile radius of a primary airport, but extended

service volumes are permitted. GLS provides for both vertical and lateral flight path specification to the

touchdown zone of the runway(s) served, and a lateral path for rollout or takeoff guidance. GLS

characteristics should be considered as defined in ICAO Annex 10, unless otherwise specified by FAA

(e.g., FAA accepted references to RTCA SC-159 MASPS).

U.S. GLS systems should be operationally classified by "Type" for each runway end served, similar to

ILS (e.g., GLS II/D/2). The operational classification is intended to address at least the service provided

in terms of “Type of service or performance level”, “area of service” relative to each specific runway

served, and level of availability or continuity. As with ILS, the classification schema should not be

specified in terms of specific minima Categories (e.g., Category III), since onboard aircraft equipment

capability or other factors may determine actual minima to be authorized.
07/13/99 AC 120-28D

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GLS systems are intended to provide equivalent or better service to that provided by a U.S.

Type I ILS, including: 1) Adequate guidance over the runway for takeoff or landing rollout

(e.g., autoland), and 2) Vertical guidance on approach down to at least 100’HAT. GBAS local area

augmentation systems (e.g., LAAS) are usually considered to support this objective. Wide area

augmentation systems (e.g., WAAS, EGNOS) are typically considered to be RNAV systems, and are

not alone considered to be GLS.

Authorization for use of GLS is for each specific air carrier, aircraft, and GLS system type until pertinent

GLS international standards accepted by FAA are promulgated.

4.4. RNAV/Flight Management Systems (FMS). RNAV/Flight Management Systems (FMS) are

typically used in conjunction with Category III Instrument Approach Procedures only for initial or

intermediate approach segments, or for missed approach.

For departure, RNAV/Flight Management Systems (FMS) may be used for non-visual takeoff guidance

after passing the height at which LNAV or VNAV may respectively be engaged or made active, or above

35' AGL, whichever is higher. Other applicable FAA criteria (e.g., section 121.189) must be addressed for

takeoff. For development or authorization of departure procedures which follow completion of a low

visibility takeoff, FAA Orders 8260.40A, 7100.1, or other applicable RNAV/RNP criteria should be

consulted.

Procedures based on 3D or 2D RNAV may or may not include use of RNP. For RNP operations, see

section 4.5 below.

4.5. Required Navigation Performance (RNP). A definition for Required Navigation Performance

(RNP) is specified in Appendix 1. Standard Levels of RNP typically used for various initial, intermediate

approach and missed approach segments for Category III procedures may be based on specific landing

systems (e.g., ILS, MLS, or GLS), on multisensor RNAV (e.g., FMS with IRS, VOR, DME inputs), or

on other aircraft navigation systems having FMS like capabilities (e.g., GPS Navigation Systems).

RNP applications used for a final approach segment supporting a Category III procedure are typically

be based on use of a specific landing system sensor (e.g., ILS, MLS, or GLS), or on multisensor

RNAV systems having suitable flight critical performance.

Aircraft/systems RNP capability is typically determined by assessing RNP total system error components,

Path Definition Error (PDE), Position Estimation Error (PEE) and Flight Technical Error (FTE). In

additional to total system error (TSE) components, associated assurance limits are considered to

determine what levels of navigation performance may actually be achieved with integrity. Assessment may

specify that certain RNP levels may only be achieved with flight director or autopilot coupled operation,

or that for particular applications availability must be based on use of dual independent navigation systems

(e.g., as with the/E equipment classification).
AC 120-28D 07/13/99

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4.5.1. Standard RNP Types. Standard values of RNP supporting initial, intermediate, or final

approach segments, or missed approach segments applicable to Category III procedures are as

specified in Table 4.5.1-1 below.

Table 4.5.1-1

STANDARD RNP TYPES APPLICABLE TO Category III

RNP Type Applicability/Operation

(Approach segment)

Normal Performance

(95%)

Containment

Value

RNP 1 Initial/Intermediate/

Missed approach

+/- 1 nm +/- 2 nm

RNP 0.5 Initial/Intermediate/

Missed approach

+/- 0.5 nm +/- 1 nm

RNP 0.3 Initial/Intermediate/

Missed approach

+/- 0.3 nm +/- 0.6 nm

RNP levels as

specified for lowest

Category I

Final approach/

initial missed approach

(but not below 200' HAT)

(See AC 120-29,

as amended

(See AC 120-29,

as amended)

RNP levels as

specified for

Category II

Final approach/

initial missed approach

(but not below 100' HAT)

(See AC 120-29,

as amended)

(See AC 120-29,

as amended)

RNP 0.003/15 Final approach/

initial missed approach

(any altitude)

+/- 0.003 nm

+/- 15 ft. (*)

+/- 0.006 nm

+/- 30 ft. (*)

(*) Note: vertical accuracy does not apply below 100 ft. HAT - below 100 ft. HAT vertical

performance is determined by applicable standards for touchdown performance.

RNP is a required navigation performance level described by the specification of a numeric value

indicating the required navigation accuracy for a specific operation, typically specified laterally in nautical

miles - e.g., RNP 1 is a Required Navigation Performance of ± 1 nautical mile

(95% Probability).

RNP containment is specified as RNP(X) times two (i.e., RNP(X) x 2).

Standard RNP Levels are defined for lateral performance, or lateral and vertical performance, if

applicable.

Regarding containment, the probability of exceeding the containment value without annunciation should be

assessed by some acceptable method. If assessed during an airworthiness demonstration program during

type design or STC, this probability should be considered to be at least remote (e.g., a major failure
07/13/99 AC 120-28D

Page 19

condition). If based on “fleet qualification” (e.g., use of criteria such as contained in RTCA DO-236

Appendix D for RNP) alternative methods, procedures or buffers may be used to assure protection of

containment.

Operationally, containment is typically used in procedures or separation standards in conjunction with

other operational verification procedures, other systems (e.g., TCAS, EGPWS), or operational buffers

to satisfactorily address assurance of safe operations and contingencies. This is to provide for safety in

the unlikely event operation within the containment region cannot be maintained.

In the event that operational procedures or other technical methods are not available to assure safety in

the event of loss of containment, then potential for loss of containment situations may need to be

addressed in a hazard assessment specifically keyed to an example of the intended application or

operation. More demanding uses of containment may require a higher level of assurance or a more

complex or comprehensive backup or contingency mechanism (e.g., use of an RNP Level for

specification of a lateral path for Category III flare and rollout).

4.5.2. Non-Standard RNP Types. Non-Standard RNP Types are those RNP values other than as

specified in paragraph 4.5.1. Non-Standard RNP Types are authorized by FAA on a case by case

basis where an applicant has a demonstrated need for such use.

4.6. Flight Path Definition. The following parameters, path points, or definitions may be used as a

technical basis for a variety of other references or terms eventually necessary to prepare or implement

procedures or development criteria. This section is intended to provide a technical basis for preparation

of operational concepts for use with RNAV and RNP based systems (e.g., to serve as a technical basis

for preparation of procedures criteria, operations concepts, operational manuals, or operational

authorizations). Actual procedural information, manuals, training materials and other documents used by

operators, pilots, procedure developers or others who may need to apply this information may use

simplified or summarized forms of this information, as necessary, to satisfy their particular operational

requirements.

Note: The path points and segments addressed below are those considered necessary

to support definition and operational use of systems intended for Category III. For

commonality, their definition and use are intended to be consistent with Category I and

Category II. It should be noted, however, that various GNSS or other RNAV

applications or criteria currently use or propose use of other similar points or

waypoints, use different terminology, or use different definitions for points (e.g.,

Landing Threshold Waypoint). Accordingly, since U.S. and international terminology

and definitions for such points are evolving, it is important to confirm and assure

suitability of each point used, for consistency of terminology, suitable definition, and

suitable application.
AC 120-28D 07/13/99

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Landing and Rollout Flight Path - The following criteria specifies certain reference points and other

criteria necessary to effectively implement landing and rollout operations using a landing system where

the required flight path is not inherent in the signal structure of the navigation aid (e.g., satellite systems).

The location of points used to describe the landing and rollout flight path are shown in Figure 4.6-1.

Runway Datum Point (RDP) - The RDP is used in conjunction with the FPAP and a vector normal to

the WGS-84 ellipsoid at the RDP to define the geodesic plane of a final approach flight path to the

runway for touchdown and rollout. It is a point at the designated lateral center of the landing runway

defined by latitude, longitude, and ellipsoidal height. The RDP is typically a surveyed reference point

used to connect the approach flight path with the runway. The RDP may or may not necessarily be

coincident with the designated runway threshold.

Flight Path Alignment Point (FPAP) - The FPAP is used in conjunction with the RDP and a vector

normal to the WGS-84 ellipsoid at the RDP to define the geodesic plane of a final approach and landing

flight path. The FPAP may be the RDP for the reciprocal runway.

Flight Path Control Point (FPCP) - The FPCP is a calculated point located above the RDP in a

direction normal to the WGS-84 ellipsoid. The FPCP is used to relate the vertical descent of the final

approach flight path to the landing runway.

Datum Crossing Height [DCH] - The height (feet) of the FPCP above the RDP.

Glide Path Angle [GPA] - The glide path angle is an angle, defined at the FPCP, that establishes the

descent gradient for the final approach flight path of an approach procedure. It is measured in the

geodesic plane of the approach (defined by the RDP, FPAP, and WGS-84 ellipsoid’s center). The

vertical and horizontal references for the GPA are a vector normal to the WGS-84 ellipsoid at the RDP

and a plane perpendicular to that vector at the FPCP, respectively.

Glidepath Intercept Reference Point [GIRP] - The GIRP is the point at which the extension of the

final approach path intercepts the runway.

Figure 4.6-1
07/13/99 AC 120-28D

Page 21

Datum Crossing

Height (DCH)

Runway Datum

Point (RDP)

Glidepath Intercept

Reference Point (GIRP)

Flight Path

Control Point

(FPCP)

Flight Path 

Alignment Point

(FPAP)

η

η = Glide Path Angle

The locations established for, and the values assigned to, the RDP, FPCP, DCH and GPA should be

selected based upon the operational need to establish the GIRP. Operational considerations include:

1. Path of wheels over threshold,

2. Need for coincidence with other aids and systems - visual and non-visual, or markings

3. Runway characteristics (e.g., local slope in the touchdown zone, general runway upslope or

downslope, runway lateral crown),

4. Actual displaced thresholds or multiple runway thresholds,

5. Actual clearways or stopways

6. Construction temporary requirements

Takeoff Flight Path. The flight path for low visibility takeoff (while on the runway) should be defined

by the RDP and FPAP.

4.7. Engine Inoperative Category III. The basic concept addressing expected flightcrew response

to non-normal situations, such as typically represented by an engine failure, is described in Section

6.1.8.
AC 120-28D 07/13/99

Page 22

Engine Inoperative Category III is specifically addressed because for some modern aircraft and systems it

is possible to retain and address Category III operating capability, as an alternate configuration. This is to

aid operators and pilots in planning for and selecting more desirable and fully considered landing airports

that may be closer in distance or time, have less adverse weather in terms of icy or short runways with

adverse winds, are better equipped to handle a diversion or emergency, or provide a timely return to land

at a takeoff airport or a closer takeoff alternate airport, in the unlikely event of engine failure or other

serious problem related to the engine failure.

With pre-planned engine inoperative Category III capability, airports and minima that otherwise may not

be considered acceptable for use could be selected by the pilot or operator without having to

subsequently justify its use based on emergency authority. This capability also has the advantage of

allowing for full pre-assessment of the aircraft capability, and engine inoperative aircraft configurations

(e.g., flap settings, electrical system capability, hydraulic system capability), approach procedure

characteristics, missed approach performance and other factors that may be difficult to assess in real

time if not previously assessed.

This capability also can permit an operator some additional flexibility in selecting alternate airports.

Accordingly Section 5.17 describes aircraft and airborne system criteria for credit for engine inoperative

Category III capability. Sections 7.1.3 item 10, and 7.2.6 address crew qualification. Section 10.8

addresses operational authorization and selection and use of alternates.

5. AIRBORNE SYSTEMS.

5.1. General.

5.1.1. Airborne Systems. Airworthiness criteria for airborne systems intended to meet criteria in this

AC are specified in paragraph 5.1.3 through 5.19 below for operational authorizations, or Appendix 2 for

takeoff, or Appendix 3 for landing and rollout for airworthiness demonstration of new or modified aircraft

types or systems.

Aircraft shown to meet provisions of Appendix 2 or 3 respectively, are considered to meet provisions

of this section.

For aircraft approved using earlier versions of this AC, airworthiness criteria for airborne systems

intended for Category III operations are as specified in criteria referenced by the approved AFM.

Airborne equipment listed in this section needs to be operative for Category III, in accordance with

provisions of applicable standard Operations Specifications (OpSpecs) and Operations Specifications

for that operator. Airframe manufacturers and individual operators may also include other optional

equipment as part of the Category III configuration, however, that equipment does not need to be

operative to conduct a Category III approach unless required by that operator's OpSpecs.
07/13/99 AC 120-28D

Page 23

Airborne systems making use of RNP capability for approach segments or missed approach segments

should be approved in accordance with or consistent with any one or more of the following criteria or

processes:

1) FANS I or FANS A systems approved through a certification program acceptable to FAA, or

2) Through reference to an acceptable standard such as RTCA DO-236 for RNP, or

3) Through reference to RTCA DO-236 Appendix D for “fleet qualification” of existing aircraft, or

4) Through other FAA or FAA accepted equivalent criteria for intended for application or

approval of RNP (e.g., TERPS or PANS-OPS RNP provisions as adopted).

5.1.2. Non-Airborne Systems. Unless otherwise specified in the Appendices to this AC,

NAVAID/landing system characteristics, including facility classification, should be considered as

specified in Section 4.3.10 above and AC 120-29 for ILS, MLS or GLS (e.g., U.S. use of ICAO

Annex 10 Criteria, FAA Order 6750.24 as amended, and the applicable NAVAID facility classification

for Category III). NAVAID facility use is predicated on applicable ILS, MLS, or GLS Type

classifications (e.g., ILS III/E/2, GLSII/D/2) or equivalent classification at non-U.S. facilities. Specific

Navigation Services are addressed in Section 5.12.

5.1.3. Takeoff Guidance Systems. When takeoff minima are predicated on use of a takeoff

guidance system, the takeoff guidance system should be demonstrated to meet provisions of this

paragraph or provisions specified in Appendix 2 by an airworthiness demonstration. Takeoff guidance

systems which have been shown to meet Appendix 2 by airworthiness demonstration and have a

corresponding AFM reference are typically considered to meet requirements of this paragraph.

A takeoff guidance systems shall be demonstrated to show that the airplane will not deviate significantly

from the runway centerline during takeoff while the system is being used within the limitations established

for it. Compliance may be demonstrated by flight test, or by a combination of flight test and simulation.

Flight testing must demonstrate repeatable performance, and cover those factors affecting the behavior of

this airplane (e.g., wind conditions, ILS characteristics, weight, center of gravity). Compliance with the

performance envelope should be demonstrated with pilots appropriately qualified to use the airborne

system, and should not require extraordinary skill, training or proficiency.

Demonstrated winds should be 150% of the winds for which credit is sought, but not less than 15 knots

of headwind or crosswind.

In the event that the airplane is displaced from the runway centerline at any point during the takeoff or

rejected takeoff, the system must provide sufficient guidance to enable the "pilot flying", or the pilot in

command who may assume control and become the "pilot flying", to control the airplane smoothly back

to the runway centerline without significant overshoot or any sustained nuisance oscillation.

Figure 5.1.3-1 provides the performance envelope for evaluating takeoff command guidance systems

for the following scenarios:
AC 120-28D 07/13/99

Page 24

a. Takeoff with all engines operating

b. Engine Failure at Vef - continued takeoff

c. Engine Failure just prior to V1 - rejected takeoff

d. Engine Failure at a critical speed prior to Vmcg rejected takeoff: (Vef < Vmcg)

Note: For that portion of the flight path following liftoff, the demonstrated lateral path

may be adjusted for any effect of wind drift when showing compliance with the

performance envelope below.

Airplane Speed

Failure/Continued Take-off

Runway

Centerline

VFAILURE

+ 7m

0

+ 14m

Airplane Speed

All Engines Take-off

Runway

Centerline

V1

VLOF

+ 7m

0

Airplane Speed

Failure/Rejected Take-off

Runway

Centerline

VFAILURE

+ 7m

0

+ 14m

h=35'

+ 14m

h=35'

STOP

FIGURE 5.1.3-1.

5.2. Airborne Systems for Category III Minima Not Less than RVR600. The following

equipment in addition to the instrument and navigation equipment required by 14 CFR part 91 for IFR

flight is the minimum aircraft equipment considered necessary for Category III:
07/13/99 AC 120-28D

Page 25

1. A redundant flight control or guidance system, demonstrated in accordance with Appendix 3, or for

aircraft types previously demonstrated acceptable earlier criteria described in previous versions of AC

120-28 as amended, or acceptable international criteria, such as the JAR AWO.

Acceptable flight guidance or control systems include the following:

a. A Fail Operational or Fail Passive automatic landing system at least to touchdown, or

b. A Fail Operational or Fail Passive manual flight guidance system providing suitable head-up

or head-down command guidance, and suitable monitoring capability at least to touchdown, or

c. A hybrid system, using automatic landing capability as the primary means of landing at least

to touchdown.

d. Other system which can provide an equivalent level of performance and safety.

NOTE: For system concepts not currently approved by FAA or system concepts not

addressed by Appendix 3, a proof of concept demonstration is required prior to

either airworthiness or operational consideration for approval.

2. An automatic throttle or automatic thrust control system which meets Appendix 3, or

appropriate earlier criteria as specified in an FAA-approved AFM. However, for operations with a 50

foot Decision Height, or other operations that have specifically been evaluated such as for engine

inoperative landing capability, automatic throttles may not be required if it has been demonstrated that

operations can safely be conducted, with an acceptable work load, without their use.

3. At least two independent navigation receivers/sensors providing lateral and vertical position or

displacement information, typically with the first pilot's station receiving information from one and the

second pilot's station receiving information from the other. The navigation receivers/sensors must meet

the criteria specified in Appendix 3 or equivalent, or must meet an earlier acceptable criteria as specified

in an FAA AFM (e.g., 2 ILS localizer and glide slope receivers meeting performance requirements of

AC 120-28C; Appendix 1, paragraph 7a & b).

4. At least two approved radio altimeter systems which meet the performance requirements

outlined in Appendix 3, or acceptable earlier criteria, as specified in an FAA AFM, typically with the

first pilot's station receiving information from one and the second pilot's station receiving information

from the other.

5. Failure detection, annunciation, and warning capability, as described in Appendix 3, or as

determined acceptable by earlier criteria, such as 120-28C; Appendix 1, paragraph 7c & 7g, and

specified in an FAA AFM.

6. Missed approach guidance provided by one or more of the following means:
AC 120-28D 07/13/99

Page 26

a. Attitude displays which include suitable pitch attitude markings, or a pre-established

computed pitch command display.

b. An approved flight path angle display, or

c. An automatic or flight guidance go-around capability.

7. Suitable forward and side flight deck visibility for each pilot, as specified in 5.13.1.

8. Suitable windshield rain removal, ice protection, or defog capability as specified in 5.13.2.

5.3. Airborne Systems for Category III Minima Less Than RVR600.

5.3.1. Airborne Systems for Category III Minima Not Less than RVR400. The following

equipment in addition to the instrument and navigation equipment required by part 91 for IFR flight is the

minimum aircraft equipment considered necessary for Category III operations to minima less than

RVR600 but not less than RVR400:

1. A redundant flight control or guidance system, demonstrated in accordance with Appendix 3, or for

aircraft types previously demonstrated acceptable earlier criteria described in previous versions of AC

120-28 as amended, or acceptable international criteria, such as the JAR AWO.

Acceptable flight guidance or control systems include the following:

a. A Fail Operational landing system with a Fail Operational or Fail Passive automatic rollout

system, or

b. A Fail Passive landing system (limited to touchdown zone RVR not less than RVR600) with

Fail Passive rollout provided automatically or by a flight guidance system providing suitable head-up or

head-down guidance, and suitable monitoring capability, or

c. A Fail Operational hybrid automatic landing and rollout system with compatible manual flight

guidance system, using automatic landing capability as the primary means of landing.

d. Other system which can provide an equivalent level of performance and safety.

NOTE: For system concepts not currently approved by FAA or system concepts

not addressed by Appendix 3, a proof of concept demonstration is required prior to

either airworthiness or operational consideration for approval.

2. An automatic throttle or automatic thrust control system which meets Appendix 3, or

appropriate earlier criteria as specified in an FAA-approved AFM. However, for operations with a 50
07/13/99 AC 120-28D

Page 27

foot Decision Height, automatic throttles may not be required if it has been demonstrated that operations

can safely be conducted, with an acceptable work load, without their use.

3. At least two independent navigation receivers/sensors providing lateral and vertical position or

displacement information, typically with the first pilot's station receiving information from one and the

second pilot's station receiving information from the other. The navigation receivers/sensors must meet

the criteria specified in Appendix 3 or equivalent, or must meet an earlier acceptable criteria as specified

in an FAA AFM (e.g., 2 ILS localizer and glide slope receivers meeting performance contained in AC

120-28C; Appendix 1, paragraph 7a & b).

4. At least two approved radio altimeter systems which meet the performance criteria outlined in

Appendix 3, or acceptable earlier criteria, as specified in an FAA AFM, typically with the first pilot's

station receiving information from one and the second pilot's station receiving information from the other.

5. Failure detection, annunciation, and warning capability, as described in Appendix 3, or as

determined acceptable by earlier criteria, such as 120-28C; Appendix 1, paragraph 7c & 7g, and

specified in an FAA AFM.

6. Missed approach guidance provided by one or more of the following means:

a. Attitude displays which include calibrated pitch attitude markings, or a pre-established

computed pitch command display,

b. An approved flight path angle display, or

c. An automatic or flight guidance go-around capability.

7. Suitable forward and side flight deck visibility for each pilot, as specified in 5.13.1.

8. Suitable windshield rain removal, ice protection, or defog capability as specified in 5.13.2.

5.3.2. Airborne Systems for Category III Minima Not Less than RVR300 (75 m). Visibility

minima of RVR300 is applicable to those facilities reporting RVR in feet and which have appropriate

reporting increments in feet. Visibility minima of 75m is applicable to those facilities reporting RVR in

meters and which have appropriate reporting increments in meters.

In addition to the aircraft equipment specified in 5.3.1 above, the following equipment is required for

Category III minima not less than RVR300 (75m):

1. A Fail Operational Automatic Flight Control System, or manual flight guidance system designed

to meet fail operational system criteria, or a hybrid system in which both the fail-passive automatic

system and the monitored manual flight guidance components provide approach and flare guidance to

touchdown, and in combination provide full fail operational capability, and
AC 120-28D 07/13/99

Page 28

2. A fail operational rollout guidance or control system that can assure safe rollout to taxi speed

consisting of either:

a. A fail operational automatic rollout control system or fail operational manual flight guidance

rollout system, or

b. A hybrid system consisting of at least a fail passive automatic rollout system and a

compatible Fail Passive manual flight guidance rollout control system demonstrated in accordance with

Appendix 3; (may be approved for operations not less than RVR300), or

3. Suitable flight instruments, annunciations, or crew procedures which can reliably detect and alert

the flightcrew to abnormal lateral or vertical flight path performance during an approach to touchdown,

or abnormal lateral performance during rollout.

5.3.3. Airborne Systems for Category III Minima Less than RVR300 (75 m). In addition to the

aircraft equipment specified in 5.3.2 above, the following equipment is required for Category III minima

less than RVR300 (75m):

1. A Fail Operational Automatic Flight Control System, or manual flight guidance system designed to

meet fail operational system criteria, or a hybrid system in which both the fail-passive automatic system

and the monitored manual flight guidance components provide approach and flare guidance to touchdown,

and in combination provide full fail operational capability, and

2. A fail operational automatic, manual, or hybrid rollout control system.

5.4. Automatic Flight Control Systems and Automatic Landing Systems. Automatic Flight

Control Systems or Autoland Systems considered acceptable for Category III, include:

1) Those systems meeting pertinent criteria of Appendix 3,

2) Those systems meeting acceptable earlier FAA criteria which have already been and currently

are approved for use through operations specifications (whether or not specifically referenced in AFM

provisions), or

3) Those systems meeting other equivalent criteria (e.g., JAR AWO), found acceptable to the

FAA.

5.5. Flight Director Systems. Characteristics of Flight Director Systems (head down or head up)

used for aircraft authorized for Category III should be compatible with any characteristics of the

autopilot or autoland system used. Flight control systems which provide both autopilot control and flight

director information may or may not display flight director commands as appropriate for the system

design and operator requirements. Regardless of whether Flight Director commands are provided,
07/13/99 AC 120-28D

Page 29

situational information displays of navigation displacement must also be provided to both flightcrew

members. To assure that unacceptable deviations and failures can be detected, the displays must be

appropriately scaled and readily understandable in the modes or configurations applicable.

"Flight director systems" may be considered as "fail passive" if after a failure, the flight path of the aircraft

does not experience a significant immediate deviation due to the pilot following the failed guidance

before the pilot detects the failure and discontinues using the guidance.

5.6. Head-up Display Systems. Head-up Display systems used as the basis for a suitable Category

III authorization must provide guidance for one or both pilots as appropriate for the system design. If

information is provided to only the flying pilot, then appropriate monitoring capability must be

established for the non flying pilot. Monitoring tasks must be identified, and the non flying pilot must be

able to assume control of the aircraft in the event of system failure or incapacitation of the pilot using the

Head-up Display (e.g., for a safe go-around or completion of rollout). Head-up Display Systems

acceptable for Category III must meet provisions of Appendix 3, or acceptable earlier criteria specified

by the FAA and referenced in an AFM.

"Head-up Display systems" may be considered as "fail passive" if:

1. After a failure, the pilot using the system or pilot monitoring the system is made aware of the

failure in a timely manner, and

2. The flight path of the aircraft does not experience a significant immediate deviation from the

intended path due to the pilot following the failed guidance before the pilot flying or pilot monitoring

detects the failure, and the pilot flying discontinues using the guidance.

5.7. Enhanced/Synthetic Vision Systems. Enhanced/Synthetic Vision Systems based on millimeter

wave radar or other such sensors may be used to assure the integrity of other flight guidance or control

systems in use during Category III operations. They must be demonstrated to be acceptable to FAA in

a proof of concept evaluation and they must otherwise be in accordance with Appendix 3. Use of

Enhanced/Synthetic Vision Systems for purposes other than establishing the accuracy or integrity of

flight guidance system performance must be demonstrated to be acceptable through proof of concept

testing prior to identification of specific airworthiness and operation criteria.

5.8. Hybrid Systems. Hybrid systems (e.g., a fail passive autoland system used in combination with a

monitored HUD flight guidance system) may be acceptable for Category III if each element of the

system alone is shown to meet its respective suitability for Category III, and if taken together, the

components provide the equivalent performance and safety to a non-hybrid system as specified for the

minima sought (e.g., fail operational Category IIIb).

Hybrid systems with automatic landing capability should be based on the concept of use of the

automatic landing system as the primary means of control, with the manual flight guidance system serving

as a backup mode or reversionary mode.
AC 120-28D 07/13/99

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Manual rollout flight guidance capability must be provided for hybrid systems which do not have

automatic rollout capability. Such manual rollout capability must have been shown to have performance

and reliability at least equivalent to that of a fail passive automatic rollout system.

Any transition between hybrid system elements (e.g., control transition from autoland use to manual

control HUD use, or for response to failures) must be acceptable for use by properly qualified

flightcrews (e.g., qualified in accordance with part 121, SFAR 58, or equivalent JAA criteria, as

applicable, and standard industry practices). Transitions should not require extraordinary skill, training,

or proficiency.

For any system which requires a pilot to initiate manual control near or shortly after touchdown, the

transition from automatic control prior to touchdown to manual control using the remaining element of

the hybrid system (e.g., HUD) after touchdown must be shown to be safe and reliable.

For hybrid systems, operational procedures following failure of the automatic system or flight guidance

system prior to touchdown may require that the pilot initiate a go-around, even though the aircraft using

a hybrid system must have been demonstrated as being capable of safely completing a landing and

rollout following a failure of one of the hybrid system elements below alert height.

A hybrid system may be approved for Category III if it is shown to meet the criteria specified in Appendix

3 when approved through an airworthiness demonstration process. Alternately, a hybrid system may be

acceptable for Category III if it is determined to meet applicable airworthiness criteria for each element of

the system separately (e.g., separately meets Category III criteria for autoland and HUD), and in addition,

a successful operational suitability demonstration is completed using the individual system elements

together as a hybrid system. If acceptability is determined through an operational demonstration process,

the individual elements of the hybrid system must be shown to be compatible for both normal and nonnormal operations, and the combined system must be shown to have the necessary performance, integrity,

and availability appropriate for the operations intended.

An operator may receive approval to use an automatic landing system and a manual flight guidance system

as a Hybrid System provided, (a) each system individually meets appropriate airworthiness assessments,

and (b), that operator conducts a successful operational demonstration showing the hybrid system's

capability to meet applicable provisions of this section.

For hybrid systems used for Category III an Alert Height of 50' or higher should be used unless

otherwise approved by the FAA AFS-400.

5.9. Instruments and Displays. Flight instrument and display presentations related to Category III,

including attitude indicators, EADI’s, primary flight displays, EHSI’s, HIS’s, or other such navigation

displays must provide pertinent, reliable and readily understandable information for both normal and nonnormal conditions related to Category III landing and missed approach.
07/13/99 AC 120-28D

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Alert Height and/or Decision Height indications must be readily understandable, appropriately

highlighted, and not be compromised by effects such as typical underlying terrain on the final approach

path, and other annunciations or automatic audio call-outs. In addition, instruments and displays should

provide appropriate indications considering terrain characteristics identified in Appendix 3 Section

6.3.4. Controls for altitude or height alerts used for minima determination or alert heights should use

standard indications such as RH for radio height (or RA for radio altitude) and BARO for barometric

altitude, rather than operational designations such as DH or MDA. Use of the designation RH or RA

for height referenced values, or BARO for barometric altitude referenced values for controls or displays

do not preclude related use of display symbology color changes or use of flashing alphanumeric

symbology as the aircraft descends below a specifically referenced height or altitude value.

Situation information displays of navigation displacement must be available to both flightcrew members,

and must be appropriately scaled and readily understandable in presentations or mode of display used.

Instrument and panel layouts must follow accepted principles of flight deck design.

5.10. Annunciations. Annunciations must be clear, unambiguous, and appropriately related to the

flight control mode in use. The mode annunciation labels should not be identified by landing minima

classification. For example, LAND 2, LAND 3, Single Land, Dual Land, etc., are acceptable mode

annunciation labels, whereas, Category II, Category III, etc., should not be used. Aircraft previously

demonstrated for Category III which do not meet this criteria may require additional operational

constraints to assure the correct use of minima suited to the aircraft configuration. In addition, mode

annunciation labels must be consistent with other annunciations in the cockpit, and with the airplane

documentation.

5.11. Automatic Aural Alerts. Automatic Aural Alerts (e.g., automatic call-outs, voice callouts) of

radio altitude, or call-outs approaching landing minimums, or call-outs denoting landing minimums must be

consistent with the design philosophy of the aircraft in question. However, any automatic call-outs used

should not be of a volume or frequency that interferes with necessary flightcrew communications or normal

crew coordination procedures. Recommended automatic call-outs include a suitable alert or tone as

follows:

1. At 500 ft. (radio altitude), approaching minimums and at minimums, and

2. Altitude call-outs during flare, such as at "50" ft., "30" ft. and "10" ft., or altitudes appropriate to

aircraft flare characteristics. Low altitude radio altitude call-outs, if used, should appropriately address

the situation of higher than normal sink rate during flare, or an extended flare which may be progressing

beyond the touchdown zone.

5.12. Navigation Sensors. Various navigation sensors may be acceptable to support Category III

operations as specified in Section 4.3.10. ILS localizer and glideslope signals are the primary means

currently used for the determination of deviation from the desired path for Category III operations.

Criteria for acceptable ILS and MLS localizer and glide-slope receivers are included in Appendix 3 or in

earlier acceptable criteria used by FAA for previous demonstrations of systems for Category III. Other
AC 120-28D 07/13/99

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navigation sensors, such as GNSS, or DGNSS, may be used individually or in combination to satisfy the

necessary accuracy, integrity and availability for Category III if proof of concept demonstrations are

successfully completed and operational experience at Category I and Category II minimums is acceptable.

Navigation sensors other than ILS must meet equivalent ILS performance or appropriate RTCA or

EUROCAE criteria, unless otherwise authorized.

Appropriate marker beacon information, or equivalent, must be displayed to each pilot for the outer,

middle and inner markers. Appropriate substitutes for marker beacons may be authorized by the FAA

for Category III based upon the use of suitable GNSS/DGNSS capabilities, or DME.

5.13. Supporting Systems and Capabilities.

5.13.1. Flight Deck Visibility. Suitable forward and side flight deck visibility for each pilot should be

provided as follows:

a. The aircraft should have a suitable visual reference cockpit cutoff angle over the nose for the

intended operations, at the intended approach speeds, and for the intended aircraft configurations, as

applicable (e.g., flap settings),

b. The aircraft's flight deck forward and side windows should provide suitable visibility for taxi and

ground operations in low visibility, and

c. Placement of any devices or structure in the pilots visual field which could significantly affect the

pilot's view for low visibility operations must be acceptable (e.g., HUD drive electronics, sunvisor

function or mountings).

5.13.2. Rain and Ice Removal. Suitable windshield rain removal, ice protection, or defog capability

should be provided as specified below:

a. Installation of rain removal capability is required (e.g., windshield wipers, windshield bleed air).

b. Installation and use of windshield hydrophobic coatings, or use of equivalent rain repellent

systems which meet pertinent environmental standards are recommended.

c. Installation of windshield anti-ice or de-ice capability is required for aircraft intended to operate

in known icing conditions during approach and landing.

d. Installation of at least forward windshield defog capability is recommended for aircraft subject to

obscuration of the pilot's view during humid conditions.
07/13/99 AC 120-28D

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Aircraft subject to obscuration of the windshield due to rain, ice, or fogging of the pilot's view which do

not have protection, or which do not have adequate protection may require operational limitations on

the conditions in which low visibility operations are conducted.

5.13.3. Miscellaneous Systems. Other supporting systems should meet appropriate criteria

compatible with Category III Operational Objectives. Applicable criteria may include criteria as

specified in Appendix 3, criteria as specified in basic airworthiness requirements applicable to U.S.

certificated aircraft, or equivalent, or operational criteria for IFR flight. Regarding supporting systems,

“In-service aircraft” or “new production” aircraft may meet or continue to meet criteria previously found

acceptable for Category III operation for supporting systems for those aircraft. Supporting systems for

Category III are considered to include, as applicable: Instruments, radar altimeters, air data computers,

inertial reference units, attitude and heading gyros, instrument switching, flight deck night lighting, landing

lights and taxi lights, position lights, turnoff lights, recognition lights, GPWS or EGPWS, flight data

recorders or other low visibility related aircraft systems pertinent to a particular type.

Any GPWS or EGPWS systems interfaces (e.g., glide slope deviation warning) should be compatible

with and should not interfere with the Category III Operations to be conducted (e.g., for engine

inoperative Category III Configurations). For multimode capable systems for Category III (e.g., MMR),

interfaces with GPWS or EGPWS for each MMR mode (e.g., ILS, MLS or GLS) should be consistent.

For Flight Data Recorders (FDR’s) or Quick Access Recorders (QAR’s), it is recommended that

operators consider appropriate flight data recorder requirements for incident or event analysis when

addressing provisions for Category III. It is recommended that any data recorders installed provide

sufficient capability for recording of parameters applicable to flight guidance system performance for use

with Category III operations. Typical parameters of interest and appropriate sample rates are those

found in Appendix 8 applicable to Irregular Terrain Assessment.

5.14. Go-Around Capability. Regardless of the flight guidance system used an appropriate goaround mode/capability should be provided. A go-around mode/capability must be able to be selected

at any time during the approach to touchdown. The go-around mode/capability should provide

information for a safe discontinuance of the approach at any point to touchdown, if activated prior to

touchdown. If activated at a low altitude where the aircraft inadvertently touches the ground, the goaround mode should provide adequate information to accomplish a safe go around and not exhibit

unsafe characteristics as a result of an inadvertent touchdown. Inadvertent selection of go-around after

touchdown should have no adverse effect on the ability of the aircraft to safely rollout and stop.

5.15. Excessive Deviation Alerting. An acceptable method should be provided to detect excessive

deviation of the aircraft laterally and vertically during approach, and laterally during rollout, as applicable.

The method used should not require excessive workload or undue attention. This provision does not

require a specified deviation warning method or annunciation, but may be addressed by parameters

displayed on the ADI, EADI, or PFD. When a dedicated deviation warning is provided, its use must not

cause excessive nuisance alerts.
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5.16. Rollout Deceleration Systems or Procedures for Category III.

5.16.1. Stopping Means. A means to determine that an aircraft can be reliably stopped within the

available length of the runway is necessary to conduct Category III operations. At least one of the

following means to assess stopping performance should be used:

1. An automatic braking system which includes information for the flightcrew about appropriate

auto brake settings to be used for landing or which provides landing distance information suitable for use

by the flightcrew to determine which auto brake setting may or may not be appropriate.

2. A ground speed indicating system based on inertial information or other equivalent source such

as GNSS, together with acceptable procedures for its use.

3. A deceleration display or other indication which can advise the pilot of the adequacy of aircraft

deceleration to stop within the available runway length.

4. A runway remaining indicator display reliably showing the length of remaining runway after

touchdown.

5. A procedural means to assure a safe stop acceptable to FAA. However, a procedural means to

ensure a safe stop is not appropriate for minima less than RVR300 (75 m).

5.16.2. Antiskid Systems. Unless otherwise determined to be acceptable to the FAA, aircraft

authorized for Category III should have an operable anti-skid system installed and operative per the

applicable FAA MMEL and MEL.

The authorization for aircraft to operate using Category III minima without anti-skid is determined by the

POI for each aircraft type, considering the following factors:

1. Extra field length margin of runways to be authorized, compared with field lengths necessary for

the aircraft type, and

2. The braking system characteristics of the aircraft regarding susceptibility to tire failure during

heavy braking, and susceptibility to tire failure during operations with reduced or patchy runway surface

friction.

5.17. Engine Inoperative Category III Capability. The following criteria are applicable to aircraft

systems intended to qualify for "engine inoperative Category III" authorizations. Aircraft demonstrated

to meet "engine inoperative" provisions of Appendix 3 that have an appropriate reference to engine

inoperative Category III capability in the FAA approved AFM are typically considered to meet the

provisions listed below.
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The AFM or equivalent reference must suitably describe demonstrated approach and missed approach

performance for the engine inoperative configuration, and the aircraft must meet pertinent criteria

otherwise required for all-engine Category III or equivalent criteria. This performance data should also

be available in the automated flight planning, performance and weight and balance systems normally

used by the air carrier so as to be readily available to the pilot and, if applicable, the aircraft dispatcher.

Exceptions to all-engine Category III, or equivalent criteria, may be authorized for engine inoperative

Category III as follows:

a. The effects of a second engine failure when conducting Category III operations with an

engine inoperative need not be considered, except for a demonstration that the airplane remain

controllable when the second engine fails,

b. Crew intervention to re-trim the aircraft to address thrust asymmetry following engine loss

may be permitted,

c. Alternate electrical and hydraulic system redundancy provisions may be acceptable, as suited

to the type design (e.g., bus isolation and electrical generator remaining capability must be suitable for

the engine out configuration),

d. Requirements to show acceptable landing performance may be limited to demonstration of

acceptable performance during engine out flight demonstrations (e.g., a safe landing on the runway), and

e. Landing system "status" should accurately reflect the aircraft configuration and capability.

2. Suitable information must be available to the flightcrew at any time in flight, and particularly at the

time of a "continuation to destination" or "diversion to alternate” decision. This is to determine that the

aircraft can have an appropriate Category III approach capability when the approach is initiated (e.g.,

Non-normal checklist specification of expected configuration during approach, autoland status

annunciation of expected capability).

3. Performance should be demonstrated in appropriate weather conditions considering winds and

any other relevant factors.

5.18. Airborne System Assessment for Irregular Pre-Threshold Terrain. Not withstanding that

airworthiness demonstrations may consider irregular terrain in the pre-threshold area, special operational

evaluations are nonetheless required for certain airports having difficult pre-threshold terrain conditions (see

Section 6.2.5). Criteria for the operational evaluation of irregular pre-threshold terrain airports is contained

in Appendix 8. This criteria may be used both for operational authorizations and in conjunction with

airworthiness demonstrations for type certification (TC) or supplemental type certification (STC).
AC 120-28D 07/13/99

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5.19. Airworthiness Demonstrations of Airborne System Capability for Category III.

Airworthiness demonstrations of airborne systems not previously approved for Category III should be

in accordance with the provisions of Appendices 2 through 6. Aircraft which have previously

completed airworthiness demonstrations in accordance with earlier criteria may continue to reference

the demonstrations against earlier criteria in their AFM and may elect to continue to use earlier criteria

for continued production or demonstration of new production derivative aircraft. The criteria of this AC

must be used when seeking credit not provided by the earlier criteria, for new aircraft types, or for

significantly modified systems proposed to FAA for derivative aircraft after the date of the issuance of

this revised AC. Category III aircraft systems may be evaluated in accordance with the applicable

criteria contained in the Appendices of this AC during airworthiness demonstrations, or they may be

evaluated in conjunction with an FAA approved program with an operator, for aircraft that are "in

service" using the equivalent criteria and evaluation methods, to those specified in the Appendices to this

AC. Operational demonstrations will not be conducted based on criteria prior to this AC.

6. PROCEDURES.

6.1. Operational Procedures. Appropriate operational procedures based on the approved operator

program should be addressed. Operational procedures should consider the pilot qualification and

training program, airplane flight manual, crew coordination, monitoring, appropriate takeoff and landing

minima including specification of either a Decision Height or an Alert Height (as applicable) for landing,

crew call-outs, and assurance of appropriate aircraft configurations. Suitable operational procedures

must be used by the operator and be used by flightcrews prior to conducting low visibility takeoff or

Category III landing operations.

6.1.1. Application of AFM Provisions. The operator's procedures for low visibility takeoff or

Category III landing should be consistent with any AFM provisions specified in the normal or nonnormal procedures sections (e.g., Section 3 of the AFM) during airworthiness demonstrations.

Adjustments of procedures consistent with operator requirements are permitted when approved by the

POI. Operators should assure that no adjustments to procedures are made which invalidate the

applicability of the original airworthiness demonstration.

Where navigation performance for a specific RNP can only be achieved by specific system modes (e.g.,

coupled flight director or autopilot), the specific modes and associated RNP levels should be applied

consistent with the AFM.

Where operations are based on RNP, suitable flight manual provisions for RNP capability and use

should be provided. If not available in the AFM or Flight Crew Operating Manual (FCOM), RNP

operations may be approved on a case by case basis, consistent with “fleet qualification” for RNP

criteria such as found in RTCA DO-236 Appendix D, or equivalent FAA criteria.

6.1.2. Crew Coordination. Appropriate procedures for crew coordination should be established so

that each flightcrew member can carry out their assigned responsibilities. Briefings prior to the
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applicable takeoff or approach should be specified to assure appropriate and necessary crew

communications. Responsibilities and assignment of tasks should be clearly understood by

crewmembers.

6.1.3. Monitoring. Operators should establish appropriate monitoring procedures for each low

visibility takeoff, approach, landing, and missed approach. Procedures should assure that adequate

crew attention can be devoted to control of aircraft flight path, displacements from intended path, mode

annunciations, failure annunciations and warnings, and adherence to minima associated with DH and

AH. Where a "monitored approach" is used, (e.g., where the First Officer is responsible for control of

the aircraft flight path by monitoring of the automatic flight system) appropriate procedures should be

established for transfer of control to the captain who will be making the decision for continuation of the

landing at or prior to Decision Height or Alert Height. Monitoring procedures should not require a

transfer of responsibility or transfer of control at a time that could interfere with safe landing of the

aircraft. Procedures for calling out failure conditions should be pre-established, and responsibility for

alerting other crewmembers to a failure condition should be clearly identified.

6.1.4. Use of the Decision Height or Alert Height. Decision heights are normally used for Fail

Passive Category III operations and Alert Heights are used for Fail Operational Category III operations.

Certain exceptions are noted elsewhere in this AC (e.g., use of a Decision Height (DH) due to specific

fail operational aircraft characteristic at a runway with irregular pre-threshold terrain). When Decision

Heights are specified, procedures for setting various reference bugs in the cockpit should be clearly

identified, responsibilities for Decision Height call-outs should be clearly defined, and visual reference

requirements necessary at Decision Height should be clearly specified so that flightcrews are aware of the

necessary visual references that must be established by, and maintained after passing Decision Height.

When Alert Heights are specified, the operator may elect to use an Alert Height at or below 200 ft. HAT

as suitable for procedure or procedures identified for use by that operator.

Procedures should be specified for call-out of the Alert Height and if applicable for conversion of the

Alert Height to a Decision Height in the event that the aircraft reverts from Fail Operational to Fail

Passive flight control.

The operator should assure that at each runway intended for Category III operations, the radar altimeter

systems used to define Alert Height or Decision Height provides consistent, reliable, and appropriate

readings for determination of Decision Height or Alert Height in the event of irregular terrain underlying

the approach path, or an alternate method should be used. Alert Height or DH may be based on other

means (e.g., inner marker) only when specifically approved by FAA. Any adjustments to approach

minima or procedures made on final approach should be completed at a safe altitude (e.g., above 500

ft. HAT).
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6.1.5. Call-outs. Altitude/Height call-outs should be used for Category III. Callouts may be

accomplished by the flightcrew or may be automatic (e.g., using synthetic voice call-outs or a tone

system). Typical call-outs acceptable for Category III include a combination of the following:

• "1000 ft." above the touchdown zone,

• "500 ft." above the touchdown zone,

• "approaching minimums,"

• "minimums,"

• altitudes during flare, (e.g., 50, 30, 10) or AFGS mode transitions (e.g., flare, rollout), and

• as appropriate, auto spoiler, reverse thrust deployment and autobrake disconnect.

Calls made by the flightcrew should not conflict with the automatic systems or auto call-outs of the

aircraft, and conversely the configuration selected for the aircraft should not conflict with expected callouts to be made by the flightcrew. Compatibility between the automatic call-outs and the crew call-outs

must be assured. The number of call-outs made, either automatically, by crew, or in combination,

should not be so frequent as to interfere with necessary crew communication for abnormal events.

Also, call-outs should be specified to address any non-normal configurations, mode switches, failed

modes, or other failures that could affect safe flight, continuation of the landing, or the accomplish-ment

of a safe missed approach. Any use of crew initiated call-outs at altitudes below 100 ft. should assure

that the callouts do not require undue concentration of the non-flying pilot on reading of the radar

altimeter rather than monitoring the overall configuration of the aircraft, mode switching, and

annunciations that might be related to a successful Category III landing. Automatic altitude call-outs or

tones are recommended for altitude awareness, at least at and after passing Decision Height or Alert

Height.

Operators may make provision for use of crew verbal callouts as a backup, or in lieu of automatic

callouts in certain circumstances. It is recommended that operators have a policy addressing

procedures to be used when an automatic callout system fails or is inoperative regarding making some

or all key callouts manually. Examples of when use of verbal crew callouts may be appropriate instead

of or to augment automatic callouts include:

1) When an automatic callout system has failed,

2) When automatic callouts are inoperative through an MEL provision, or

3) When a particular automatic callout is not issued or is masked by another cockpit advisory or crew

conversation, or is not heard for some other reason.
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6.1.6. Aircraft Configurations. Operational procedures should accommodate any authorized aircraft

configurations that might be required for low visibility takeoff or Category III approaches or missed

approaches. Examples of configurations that operational procedures may need to accommodate

include:

1. Alternate flap settings approved for Category III,

2. Use of alternate AFGS modes or configurations (e.g., Single Land, LAND2),

3. Inoperative equipment provisions related to the minimum equipment list, such as a non-availability of

certain electrical system components, inoperative radar altimeter, air data computers, hydraulic systems or

instrument switching system components, and

4. Availability and use of alternate electrical power sources (e.g., APU) if required as a standby source.

Procedures required to accommodate various aircraft configurations should be readily available to the

flightcrew and the aircraft dispatcher to preclude the inadvertent use of an incorrect procedure or

configuration. Acceptable configurations for that operator and aircraft type should be clearly identified

so that the pilots can easily determine whether the aircraft is or is not in a configuration to initiate a low

visibility takeoff or Category III approach. Configuration provisions must be consistent with, but are not

limited to, those provided in the operations specifications for that operator.

6.1.7. Compatibility with Category I and Category II Procedures. The operator should assure

that to the greatest extent possible, procedures for Category III are consistent with the procedures for

that operator for Category II and Category I to minimize confusion about which procedure should be

used or to preclude procedural errors due to pilots reverting to familiar procedures accomplished more

frequently such as for Category I. The operator should to the extent practical, minimize the number of

procedures that the crew needs to be familiar with for low visibility operations so that, regardless of the

landing category necessary for an approach, the correct procedures can be used consistently and

reliably.

6.1.8. Flightcrew Response to Non-Normal Events. Takeoff and landing weather minimums are

intended for normal operations. When non-normal events occur, flightcrews and aircraft dispatchers are

expected to take the safest course of action to assure safe completion of the flight. Using emergency

authority, pilots can deviate from rules or polices, to the extent necessary, to minimize the risk of

continued flight to a safe landing. In some instances, guidelines are established for particular failure

situations, such as failure of required aircraft systems prior to reaching Alert Height.

When procedures or configurations have not been specified, pilots and aircraft dispatchers are expected

to use good judgment in making the determination of appropriate configurations or situations to conduct

safe Category III operations. The decision to continue an approach or to discontinue an approach must
AC 120-28D 07/13/99

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be made considering all relevant factors of the status of the aircraft, fuel on board, seriousness of the

emergency, distance away of other available airports, and the likelihood of changing weather conditions,

among other factors. It is not the intent of this AC to attempt to define guidelines for circumstances such

as in-flight fire, minimum fuel reserves, or other situations requiring complex judgments of skilled

crewmembers.

However, in the case of certain well-defined situations that can be addressed before departure, such as

contingency planning in the event of an engine failure, guidelines are provided to assist pilots in making

safe and consistent judgments about available alternative courses of action. Specific guidelines for

initiation for a Category III approach with an inoperative engine are provided in section 5.17.

Guidelines for other configuration situations may be provided by the normal or non-normal procedure

section of the aircraft flight manual or by the operator. Pilots and aircraft dispatchers are expected to be

familiar with these guidelines and apply them to the extent practical but may deviate as necessary from

those guidelines, to the extent that they consider necessary to assure safe flight and landing. If doubt

exists as to the advisability of continuation of an approach or diversion, it is the flightcrews responsibility

to exercise their emergency authority to the extent necessary to assure a safe flight.

6.2. Category III Instrument Approach Procedures and Low Visibility Takeoff.

6.2.1. Takeoff Guidance System Procedures. When takeoff minima are predicated on use of a

takeoff guidance system meeting the criteria of Section 5.1.3 or Appendix 2, procedures for use of the

takeoff guidance system should be identified consistent with the approved AFM, or applicable operational

authorization. Procedures should address at least the following items or factors:

• Setup, test, and initialization of the guidance system and NAVAID’s, as applicable

• Roles and responsibilities of the PF and PNF

• Suitable alignment with and tracking of the runway centerline

• Suitable transfer of control between pilots for failures or incapacitation, as applicable

• Suitable response to failures (e.g., engine failure before and after V1, electrical failure, guidance

system alerts, warnings, and failures as applicable)

6.2.2. Acceptable Procedures for Category III Approach. Instrument Approach Procedures for

Category III may be conducted in accordance with:

1. published 14 CFR part 97 procedures, or

2. approved operations specifications for special procedures, or
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3. published foreign or military procedures approved by the FAA, or

4. foreign or military procedures accepted by FAA for specific foreign airports and runways.

6.2.3. Standard Obstacle clearance for approach and missed approach. Advisory Circular 120-

29 as amended provides the standard Category II and III approach and missed approach criteria not

otherwise specified in FAA Order 8260.3 (TERP’s). The criteria in AC 120-29 should be applied

except where acceptable TERP’s criteria is provided for Category II and III operations using ILS,

MLS, GLS or RNP facilities and equipment. Standard obstacle clearance criteria are typically

incorporated with published part 97 procedures. Standard criteria used by several foreign authorities

based on ICAO PANS OPS may be used where found to be acceptable to the FAA (e.g., JAA

approved procedures). Category II and III procedures developed using criteria other than TERPS or

PANS OPS are normally issued through operations specifications as special procedures. (See

paragraph 6.2.4.)

6.2.4. Special Obstacle Criteria. In certain instances standard obstacle criteria as specified by

TERPS may not be appropriate for particular Category III procedures. In such instances alternate

criteria acceptable to the FAA may be used as specified in OpSpecs (e.g., RNP criteria).

6.2.5. Irregular Terrain Airports. Irregular terrain airports identified by a part 97 procedure, or by

FAA order 8400.8, as amended, must be evaluated in accordance with FAA approved procedures

prior to incorporation in operations specifications for use by air carriers operating to Category III

minima.

Irregular terrain airport special evaluations should consider each particular aircraft type, the particular

flight control system, and may include consideration of particular system elements such as the type of

radar altimeters installed or other equipment.

Procedures for evaluation of these airports are provided in Appendix 8.

6.2.6. Airport Surface Depiction for Category III Operations. A suitable airport surface

depiction (e.g., airport diagrams) should be available to flightcrews to assure appropriate identification

of visual landmarks or lighting to safely accomplish taxing in Category III conditions from the gate to the

runway and from the runway to the gate. The Airport depiction should use an appropriate scale with

suitable detailed information on gate locations, parking locations, holding locations, critical areas,

obstacle free zones, taxi way identifications, runway identifications, and any applicable taxi way

markings for designated holding spots or holding areas. Standard depictions provided by commercial

charting services are typically acceptable if they provide sufficient detail to identify suitable routes of taxi

to and from the runway and gate positions for departure or arrival.

6.2.7. Continuing Category III Approaches in Deteriorating Weather Conditions. The

following procedures are considered acceptable in the event that weather conditions are reported to

drop below the applicable Category III minima after an aircraft has passed the final approach point or

final approach fix, as applicable. (Reference section 121.651.)
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• Operations based on a DA(H) may continue to the DA(H) and then land, if the specified visual

reference is subsequently established by the pilot no later than the DA(H).

• Operations based on an Alert Height (AH) may continue to the AH and then land, if weather is

reported to be at or above minima before passing the AH, or if suitable visual reference has

been established by the pilot.

• Operations based on an AH may continue to land regardless of reported weather conditions if

equipped with a fail operational rollout system which did not indicate a malfunction prior to

passing alert height, and the pilot considers continuation a safe course of action.

Operators requesting amended operations specifications reflecting the procedures described above may

have their current operations specifications amended by making application in accordance with

paragraph 10.16. New Category III operators should have operations specifications issued reflecting

these provisions in accordance with revised standard operations specifications (see samples provided in

Appendix 7).

When wind constraints apply to Category III procedures (e.g., an Operation-Specification 15 knot

crosswind component limit) the limit is considered to apply to the point of touchdown. If a report of a

crosswind component value greater than the limit is received while on approach, an aircraft may

continue an approach, but a subsequent wind report indicating winds are within limits or a pilot

determination that actual winds are within limits must be made prior to touchdown. Acceptable

methods for such a determination may include ATS reports, reports of other aircraft with reliable means

of wind determination (e.g., IRS), pilot use of on board IRS or FMS wind readout capability, data link

of recent winds, or pilot confirmation of an acceptable visual indication of winds on the surface by a

wind sock, wind indicator or equivalent wind indicating device.

When an Airplane Flight Manual or other manufacturer’s reference (e.g., FCOM) references

“Maximum wind component speeds when landing weather minima are predicated on autoland

operations”, or an equivalent statement, an operator or flightcrew may consider those wind values to

apply to “steady state” wind components. Any gust values which exceed the steady state wind limit

need not be addressed if the flightcrew determines the gust exceedance can be considered insignificant

in magnitude, variable in direction, occasional, or otherwise not applicable (e.g., obviously outdated gust

report, winds and gusts reported at a location considered far from the runway or touchdown zone and

not applicable, or gusts considered not pertinent during the period of touchdown or rollout).

6.2.8. Low Visibility Taxi Procedures. Low visibility taxi procedures should be adopted for each

airport having such procedures. The procedures should be available to pilots in chart form, if

applicable, and used. In addition to published Surface Movement Guidance and Control System

(SMSGS) airport diagrams and information, the operator should provide:
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• Any necessary specific gate identification information to find gates, ramp areas, or lead in

vehicles,

• Any necessary information about identification of critical area protection zones or areas,

• Any necessary emergency response information for takeoff, landing, or other emergencies that

are different for low visibility operations (e.g., markings or other ways to easily find and identify

explosive holding areas in low visibility),

• Information on any known characteristics of the airport where aircraft ground vehicle traffic

conflicts, taxi speed, or aircraft wing tip clearance pose unusual difficulty,

• Any other information necessary to facilitate safe operations in very low visibility (e.g., visual

references that may be used for operations when standard markings may not be visible due to

construction, snow cover).

Provision should be made for both day and night operation, unless operations are only conducted during

either night or daylight hours.

Low visibility taxi and ground operations and related training and qualification are addressed in Sections

7.1.1 item 3 and 7.1.3 item 5 for ground training, Section 7.2 for flight training, and Section 8.5 for

SMGCS Plans.

6.2.9. Navigation Reference Datum Compatibility (e.g.,WGS-84/Other Datum).

Outside the U.S., it is important for operators using FMS, GPS and RNAV to be aware of, and where

necessary, take precautions to address potential differences in the Navigation Data Base (NDB)

"reference datum" used by their aircraft's navigation system, and the datum used en route and at

destination or alternate airports. Some States specify aeronautical data (e.g., NAVAID locations,

runway locations, waypoint locations), including data for instrument procedures, using a reference datum

other than the standard WGS-84 datum, or equivalent.

Addressing this difference can be important to preclude significant navigation errors. If not

appropriately addressed, aircraft actual position may significantly differ from indicated position when

flying in these areas. Aircraft may experience navigation difficulty including:

• Incorrect FMS position updating,

• Incorrect navigation to a waypoint, NAVAID, runway, or other geographic location,

• Violation of airspace or obstacle clearance during approach or missed approach,

• Displacement from the desired flight path, or runway misalignment following completion of an

instrument approach, or
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• Significant map shift, if FMS position is based on updates from NAVAID(s) referenced to a local

datum inconsistent with that of the aircraft's navigation data base.

Also, this issue can be important when flying with FMS using a WGS-84 referenced navigation data

base with "GPS updating capability" installed, but not operative (e.g., as for an FMS MEL dispatch,

with GPS inoperative, GPS updating inoperative; or GPS updating inhibited).

For Category III procedures, the issue of use of an appropriate Navigation "Reference Datum"

principally applies to flying RNAV initial or intermediate approach segments, or missed approach

segments. Final approach segments of ILS or MLS procedures typically are not adversely affected by

a difference in reference datum because of direct use of the localizer course. GLS or RNP procedures,

while depending on specification of an appropriate reference datum for final approach, are otherwise

protected from this datum difference through other criteria which assures consistent datum use for

procedure development.

Information about the navigation reference datum used in particular locations outside of the United

States is typically available on the Internet. An example of a commercial web site containing this

information may be found at: http://www.jeppesen.com/wgs84.html

Accordingly, when operating outside United States airspace and when WGS-84 is not used locally as

the reference datum for NAVAID’s or procedures, or a reference datum equivalent to WGS-84 is not

used, operators should take suitable precautions, as described below. These precautions apply to any

RNAV segments flown as part of any instrument approach procedure or missed approach procedure

(including Category III procedures, if applicable) for:

• FMS equipped aircraft capable of GPS updating, or

• GPS "stand alone" equipped aircraft, or

• FMS equipped aircraft.

a. Aircraft Equipped With FMS Having GPS Updating Capability, or Equipped With

"GPS Stand Alone" Navigation Systems.

For operations outside the United States, where the local datum is not WGS-84, or WGS-84

equivalent, or where the operator is uncertain as to whether the local datum is significantly different than

WGS-84, the operator should take one or more of the following precautions, as necessary:

1) Verify that the datum is WGS-84, or equivalent,

2) Conduct an assessment of the difference in the datum used, to determine that any difference

is not significant for the procedures to be flown,

3) Develop and use special RNAV procedure segments or aeronautical data referenced to

WGS-84 or equivalent, as necessary,
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4) Manually inhibit GPS updating of the FMS while flying the approach, or segments of the

approach affected by the difference in reference datum,

5) Only use FMS or GPS Stand Alone systems to fly pertinent RNAV segments of the

approach where it is possible to use other NAVAID raw data to confirm correct aircraft position along

the flight path,

6) Conduct simulation verification, or in-flight verification or confirmation of suitable navigation

performance,

7) Preclude FMS or GPS use on segments of the approach affected by the difference in

reference datum, or

8) Use any other method proposed by the operator, and found acceptable to FAA, to assure

that a difference in the NDB Reference Datum from the local datum does not cause loss of navigation

integrity.

For GLS or RNP procedures or procedure segments, since the reference datum is consistent with

WGS-84 by procedure design, operators of aircraft using GPS updating of FMS, or "GPS Stand

Alone" systems for RNAV need not apply the special precautions listed above, unless otherwise

advised (e.g., by NOTAM, or equivalent).

b. FMS Equipped Aircraft That Do Not Have GPS Updating Capability.

While possible, FMS equipped aircraft that do not have GPS updating capability may be less likely to

experience this particular datum reference difference issue. This is because navigation data bases, local

NAVAID’s, and local instrument procedures typically address and resolve datum issues consistently on

a local basis, and in a consistent manner within the locally used coordinate frame of reference.

However, even though the datum difference issue may be less likely, it nonetheless may occur.

Precautions should be applied by operators, as necessary, if there is significant doubt as to Navigation

Data Base datum differences.

The precautions listed above in item a. should not be interpreted to discourage GPS installation and use.

GPS updating of FMS can significantly increase both navigation accuracy and integrity, and reduce the

risk of other types of navigation errors, including map shifts, yielding a significant safety increase.

7. TRAINING AND CREW QUALIFICATION. Training and crew qualification programs pertinent

to Category III should include provisions for appropriate ground training, flight training, initial qualification,

recurrent qualification, recency of experience, and re-qualification. The operators program should

provide appropriate training and qualification for each pilot in command, second in command and any
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other crewmember expected to have knowledge of or perform duties related to Category III landing or

low visibility takeoff operations (e.g., Flight engineer).

Pilots in command are expected to have a comprehensive level of knowledge with respect to each of

the ground training subjects and have performed each of the specified maneuvers and demonstrated skill

in accomplishing each of the tasks specified for flight training. Second in command pilots should have a

comprehensive knowledge of the subjects specified in the ground training program, and are expected to

perform those relevant procedures or maneuvers applicable to the second in command is assigned

duties during Category III landing operations or for low visibility takeoff. Other crewmembers are

expected to have the knowledge required and the demonstrated skills to perform their assigned duties.

7.1. Ground Training.

7.1.1. Ground System and NAVAIDs for Category III. Ground systems and NAVAID’s are

considered to include characteristics of the airport, electronic navigation aids, lighting, marking and other

systems (e.g., RVR) and any other relevant information necessary for safe Category III landing or low

visibility takeoff operations.

The training and qualification program should appropriately address the operational characteristics,

capabilities and limitations of at least each of the following:

1. NAVAID’s. The navigation systems to be used, such as the instrument landing system with its

associated critical area protection criteria, marker beacons, distance measuring equipment, compass

locators or other relevant systems should be addressed to the extent necessary for safe operations. As

applicable, operationally relevant characteristics of NAVAID types to be used should be addressed. For

example for ILS or MLS, any characteristics of beam bends, overflight disturbances, beam switchover to

secondary transmitters or power sources, flare of the glide slope signal at low altitudes may need to be

explained or addressed depending on the characteristics of the particular flight guidance system used. If

non ground based systems (e.g., GNSS) are used, any characteristics or constraints regarding that

method of navigation, must be addressed (e.g., proper procedure waypoint selection and use, integrity

assurance, coping with space vehicle (SV) loss of availability or failure, SV terrain masking).

2. Visual aids. Visual aids include approach lighting system, touchdown zone, centerline lighting,

runway edge lighting, taxiway lighting, standby power for lighting and any other lighting systems that

might be relevant to a Category III environment, such as the coding of the center line lighting for

distance remaining, and lighting for displaced thresholds, stop ways, or other relevant configurations

should be addressed.

3. Runway and Taxiways and SMGCS Plans. The runway and taxiway characteristics concerning

width, safety areas, obstacle free zones, markings, hold lines, signs, holding spots, or taxi way position

markings, runway distance remaining markings and runway distance remaining signs should be

addressed. The SMGCS plan use should be addressed as applicable. This should include any
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necessary briefings to be conducted and crew coordination, particularly for crash and rescue,

evacuation, or other non-normal events, if different for low visibility situations.

4. Weather Reporting. Weather reporting and transmissometer systems, including RVR locations,

readout increments, sensitivity to lighting levels set for the runway edge lights, variation in the significance

of reported values during international operations, controlling and advisory status of readouts, and

requirements when transmissometers become inoperative should be addressed.

5. Facility Status. Facility status, proper interpretation of outage reports for lighting components,

standby power, or other factors and proper application of NOTAM’s regarding the initiation of

Category III approaches or initiation of a low visibility takeoff should be addressed.

7.1.2. The Airborne System. The training and qualification program should address the

characteristics, capabilities, limitations, and proper use of each appropriate airborne system element

applicable to Category III landing or low visibility takeoff including the following:

1. Flight Guidance. The flight control system, flight guidance system, instruments and displays and

annunciation systems including any associated flight director, landing system and roll out system, or

takeoff systems, if applicable. For automatic or manual systems which require crew input for

parameters such as inbound course or automatic or manually tuned navigation frequencies, the crew

should be aware of the importance of checking that proper selections have been made to assure

appropriate system performance.

2. Speed Management. The automatic throttle, FMC or other speed management system, if

applicable.

3. Instruments. Situation information displays, as applicable.

4. Supporting Systems. Other associated instrumentation and displays, as applicable, including any

monitoring displays, status displays, mode annunciation displays, failure or warning annunciations and

associated system status displays that may be relevant.

5. Aircraft Characteristics. Any aircraft characteristics that may be relevant to Category III, such

as cockpit visibility cutoff angles and the effect on cockpit visibility of proper eye height, seat position or

instrument lighting intensities related to transition through areas of varying brightness visual conditions

change. Pilots should be aware of the effects on flight visibility related to use of different flap settings,

approach speeds, use of various landing or taxi lights and proper procedures for use of windshield

wipers and rain repellent. If windshield defog, anti-ice, or de-icing systems affect forward visibility,

pilots should be aware of those effects and be familiar with proper settings for use of that equipment

related to low visibility landing.

7.1.3. Flight Procedures and Associated Information.
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1. Operations Specification. Pilots and aircraft dispatchers should be familiar with, and properly

able to apply, operations specifications applicable to Category III landing or low visibility takeoff.

2. Normal and Non-normal Procedures. Pilots should be familiar with appropriate normal and

non-normal procedures including crew duties, monitoring assignments, transfer of control during normal

operations using a "monitored approach," appropriate automatic or crew initiated call-outs to be used,

proper use of standard instrument approach procedures, special instrument approach procedures,

applicable minima for normal configurations or for alternate or failure configurations and reversion to

higher minima in the event of failures.

3. Weather and RVR. Pilots and aircraft dispatchers should be familiar with weather associated

with Category III and proper application of runway visual range, including its use and limitations, the

determination of controlling RVR and advisory RVR, required RVR equipment, appropriate light

settings for correct RVR readouts and proper determination of RVR values reported at foreign facilities.

4. Use of DA(H) or Alert Height. Pilots should be familiar with the proper application of Decision

Height or Alert Height, as applicable, including proper use and setting of radar altimeter bugs, use of the

inner marker where authorized or required due to irregular underlying terrain and appropriate altimeter

setting procedures for the barometric altimeter consistent with the operators practice of using either

QNH or QFE.

5. Use of Visual Reference. Pilots should be familiar with the availability and limitations of visual

reference encountered for taxi, takeoff, and approach.

Approach visual reference limitation information should at least address aircraft geometry limitations on

visual reference, actions to take with loss or partial loss of visual reference, risks of inappropriate use of

visual reference, and necessary visual references for continuation after Decision Height, if a Decision

Height is applicable. Issues listed in section 6.2.7 above for continuation or discontinuation of an

approach in deteriorating weather conditions should be comprehensively addressed.

Pilots should be familiar with procedures for an unexpected deterioration of conditions to less than the

minimum visibility specified for the procedure during an approach, flare or roll out including the proper

response to a loss of visual reference or a reduction of visual reference below the specified values when

using a Decision Height and prior to the time that the aircraft touches down. The operator should

provide some means of demonstrating the expected minimum visual references that occur on approach

when the weather is at acceptable minimum conditions, and the expected sequence of visual queues

during an approach in which the visibility is at or above the specified landing minimums. This may be

done using simulation, video presentation of simulated landings or actual landings, slides or pictures

showing expected visual references, computer based reproductions of expected visual references, or

other means acceptable to the FAA.
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When an alert height is used, pilots should be familiar with the expected visual references sequence

likely to be encountered during an approach, even though a specific regulatory visual reference is not

established when using an alert height.

When a synthetic reference system such as "synthetic vision" or enhanced vision systems or independent

landing monitors are used, pilots should be familiar and current with the interpretation of the displays to

assure proper identification of the runway and proper positioning of the aircraft relative to continuation of

the approach to a landing. Pilots should be briefed on the limitations of these systems for use in various

weather conditions and specific information may need to be provided on a site-specific basis to assure

that mis-identification of runways, taxiways or other adjacent runways does not occur when using such

systems.

For takeoff, pilots should be aware of the operators policy for responding to loss of suitable visual

reference during takeoff, in the low and high speed regime, both before and after V1 (see FAA

AC 120-62 “Takeoff Safety Training Aid” for additional information and recommendations for training).

6. Transfer of Control. Procedures should be addressed for transfer of control and transition from

non-visual to visual flight for both the pilot in command, second in command, as well as the pilot flying

and pilot not flying during the approach. For systems which include electronic monitoring displays, as

described in item 5 above, procedures for transition from those monitoring displays to external visual

references should be addressed.

7. Acceptable Flight Path Deviations. Pilots should be familiar with the recognition of the limits of

acceptable aircraft position and flight path tracking during approach, flare and if applicable roll out. This

should be addressed using appropriate displays or annunciations for either automatic landing systems or

for manual landing systems or when using electronic monitoring systems such as an independent landing

monitor.

8. Wind Limitations. Environmental effects should be addressed. Environmental effects include

appropriate constraints for head winds, tail winds, cross winds, and the effect of vertical and horizontal

wind shear on automatic systems, flight directors, or other system (e.g., synthetic vision) performance.

For systems such as head-up displays which have a limited field of view or synthetic reference systems

pilots should be familiar with the display limitations of these systems and expected pilot actions in the event

that the aircraft reaches or exceeds a display limit capability.

9. Contaminated Runways. Pilots and aircraft dispatchers should be familiar with the operator’s

policies and procedures concerning constraints applicable to Category III landings or low visibility takeoffs,

on contaminated or cluttered runways. Limits should be noted for use of slippery or icy runways as far as

directional control or stopping performance is concerned, and crews should be familiar with appropriate

constraints related to braking friction reports. Pilots and aircraft dispatchers should be familiar with the

method of providing braking friction reports applicable to each airport having Category III landing

operations or low visibility takeoff operations.
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10. Airborne System Failures. Pilots should be familiar with the recognition and proper reaction to

significant airborne system failures experienced prior to and after reaching the final approach fix and

experienced prior to and after reaching Alert Height or Decision Height, as applicable. Expected pilot

response to failure after touchdown should be addressed, particularly for Category III operations.

Engine inoperative Category III provisions should be addressed, if applicable, including identification of

acceptable aircraft and system configurations, assurance of adequate obstacle clearance and missed

approach performance, and appropriate use of alternates. If applicable, provisions for “engine

inoperative Category III” should be addressed.

11. Go-around Provisions. Pilots are expected to appropriately recognize and react to ground or

navigation system faults, failures or abnormalities at any point during the approach, before and after

passing Alert Height or Decision Height and in the event an abnormality or failure which occurs after

touchdown. Pilots should be familiar with appropriate go-around techniques, systems to be used either

automatically or manually, consequences of failures on go-around systems which may be used, the

expected height loss during a manual or automatic go around considering various initiation altitudes, and

appropriate consideration for obstacle clearance in the event that a missed approach must be initiated

below Alert Height or Decision Height.

12. Reporting Anomalies. Pilots should be familiar with the need to report navigation system

anomalies or discrepancies, or failures of approach lights, runway lights, touchdown zone lights, center

line lights or any other discrepancies which could be pertinent to subsequent Category III operations.

7.2. Flight Training (Aircraft or Simulator). Flight training (typically using a simulator) should

address the following maneuvers and procedures and may be done individually as Category III

maneuvers, or they may be accomplished in appropriate combinations with Category I or Category II

maneuvers. When pilots are authorized to use minima for Category I or Category II, as well as

Category III, maneuvers may be appropriately combined and done in conjunction with other required

approaches necessary for Category I or Category II training and qualification when such combinations

are appropriate (e.g., engine-inoperative missed approach). During each of the specified maneuvers or

procedures, crewmembers are expected to perform their respective assignments or duties as applicable.

In situations where crewmembers are being qualified, other than as part of the complete flightcrew, such

as when two pilots in command are being qualified, it may in some cases be necessary to assure that

each candidate completes the required maneuvers or procedures involving manual control of the aircraft

or other demonstration of proficiency when such demonstration is required for a PIC.

Flight training (typically using a simulator) for Category III approach and landing should address at least

the following maneuvers:

1. Normal landings at the lowest applicable Category III minima.
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2. A missed approach from the Alert Height or Decision Height (may be combined with other

maneuvers).

3. A missed approach from a low altitude that could result in a touchdown during go-around

(rejected landing).

4. Appropriate aircraft and ground system failures (may be combined with other maneuvers).

5. Engine failure prior to or during approach (if specific flight characteristics of the aircraft or

operational authorizations require this maneuver).

6. Except for aircraft using an automatic Fail Operational roll out system, manual roll out in low

visibility at applicable minima (may be combined).

7. Landings at the limiting environmental conditions authorized for Category III for that operator

with respect to wind, cross wind components, and runway surface friction characteristics (may be

combined).

Flight training (typically using a simulator) for low visibility takeoff (e.g., RVR less than RVR500 ft./150

m), where a flight guidance system is required, should address the following maneuvers and procedures:

1. Normal takeoff,

2. Rejected takeoff from a point prior to V1 (including an engine failure),

3. Continued takeoff following failures including engine failure, and any critical failures for the

aircraft type which could lead to lateral asymmetry during the takeoff, or

4. Rejected takeoff which involve transfer of control from the first officer to the captain, if first officers

are authorized to make takeoffs under the specified low visibility conditions (if applicable).

The conditions under which these normal and rejected takeoffs should be demonstrated include

appropriate limiting cross winds, winds, gusts and runway surface friction levels authorized. A

demonstration should be done at weights or on runways that represent a critical field length. If the flight

guidance devices used have not been shown to have failure characteristics which are extremely

improbable, a takeoff and rejected takeoff should be demonstrated with failure of the flight guidance

device at a critical point of the takeoff.

Training for low visibility taxi and ground operations (e.g., during simulator training, LOFT or other

scenarios) are recommended to be conducted to the extent practical and beneficial. If conducted, they

should address at least representative items listed in Sections 6.2.8, 7.1.1, and 7.1.3 at typical airports.

Alternately, the operator may elect to use airports frequently experiencing low visibility conditions,

complex airports on the operator’s route system, airports with particular low visibility ground movement

difficulties, or rarely used but significant contingency airports (e.g., ETOPS or EROPS diversion
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airports), as determined appropriate by the operator for that operator’s route system, aircraft types,

training cycle, LOFT scenarios used, and typical line issues being experienced.

7.2.1. Initial Qualification.

1. Ground Training. Initial ground training should cover the subjects specified in 7.1 for each pilot

in command and second in command and appropriate subjects from 7.1 relevant to other crewmembers

when they have assigned responsibilities for Category III landing or low visibility takeoff.

2. Flight Training. Flight training should be conducted using an approved simulator capable of

performing the appropriate maneuvers specified, and which can appropriately represent the limiting

visual conditions related to the minima which are applicable. Where simulation is not available, an

aircraft with suitable view limiting device may be used if authorized by the assigned principal operations

inspector. While the number of simulator periods, training flights, or length of simulator periods is not

specified, the operator is expected to provide sufficient training to assure that crewmembers can

competently perform each of the maneuvers or procedures specified in 7.2 to an acceptable degree of

proficiency. When Category III minima are based on manual operations using systems like head-up

displays or flight directors, a number of repetitions of the maneuvers specified in paragraph 7.2 above

may be necessary to assure that each of the required maneuvers can be properly and reliably

performed. Guidance for acceptable programs can be found in FAA, FSB reports for specific aircraft

types. Operators should adhere to FSB guidelines when published, unless otherwise authorized by

AFS-400.

7.2.2. Recurrent Qualification.

1. Recurrent Ground Training. Recurrent ground training should provide any necessary review of

topics specified in 7.1 to assure continued familiarity with those topics. Emphasis should be place on

any program modifications, changes to aircraft equipment or procedures, review of any occurrences or

incidents that may be pertinent, and finally emphasis may be placed on re-familiarization with topics such

as mode annunciations for failure conditions or other information which the pilots may not routinely see

during normal line operations. Topics to be addressed for each pilot in command, second in command

other crewmember or aircraft dispatchers are those topics necessary for the performance of the

assigned duties for each respective crewmember.

2. Recurrent Flight Training. Recurrent flight training should be conducted using an approved

simulator with an appropriate visual system. In the event that simulation is not available, recurrent flight

training may be accomplished in the aircraft using suitable view limiting devices, if approved by the

principal operations inspector. Recurrent flight training should include at least one Category III

approach to a landing if the pilot has not had recent Category III or simulated Category III experience,

and one approach requiring a go-around from a low altitude below Alert Height or Decision Height

prior to touchdown.
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When takeoff minimums below RVR500 are approved, recurrent flight training must include at least one

rejected takeoff at the lowest approvable minima, with an engine failure near but prior to V1. For both

Category III landings and low visibility takeoffs, sufficient training should be provided to assure

competency in each of the maneuvers or procedures listed in 7.2.

Recurrent flight training maneuvers may be accomplished individually or may be integrated with other

maneuvers required during proficiency training or during proficiency checking. If minima are authorized

using several methods of flight control such as both automatic landing and head-up display, then the

training program should assure an appropriate level of proficiency using each authorized mode or

system. Where Category III minima are based on manual control using flight guidance such as provided

by a head-up flight guidance system, appropriate emphasis should be placed on failure conditions which

a pilot does not normally experience in line operations.

7.2.3. Recency of Experience. Recency of experience requirements specified by section 121.439 or

in accordance with AC 120-53 normally provide an assurance of the necessary level of experience for

Category III landing or low visibility takeoff operations. In the event that special circumstances exist

where crewmembers may not have exposure to the automatic landing system or manual systems such as

head-up flight guidance for long periods of time beyond that permitted by section 121.439 or AC 120-

53, then the operator should assure that the necessary recency of experience is addressed prior to pilots

conducting Category III landings, or low visibility takeoff operations below RVR500.

For automatic landing systems, as a minimum, pilots should be exposed to automatic landing system

operation and procedures during training or checking in either the aircraft or in a simulator at least

annually, if the crew has not otherwise conducted line landings using an automatic system within the

previous 12 months. For manual flight guidance landing or takeoff systems the pilot flying (PF) should

be exposed to system operation, procedures, and use during training or checking at least once each 90

days, if the pilot has not otherwise conducted line landings using the manual flight guidance system within

the previous 90 days.

7.2.4. Re-qualification. Credit for previous Category III qualification in a different aircraft type or

variant, or previous qualification in the same type or variant at an earlier time may be considered in

determining the type of program, length of program, required maneuvers to be completed or the

repetition of maneuvers for re-qualification for Category III operations. Any re-qualification program

should assure that the pilots have the necessary knowledge of the topics specified in section 7.1 and are

able to perform their assigned duties for Category III or low visibility takeoff considering the maneuvers

or procedures identified in section 7.2.

For programs which credit previous Category III qualification in a different type aircraft, the transition

program should assure that any subtle differences between aircraft types which could lead to pilot

misunderstanding of appropriate characteristics or procedures in the new type must be suitably

addressed.
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7.2.5. Cockpit or Aircraft System Differences. For Category III programs using aircraft which have

several variants, training programs should assure that pilots are aware of any differences which exist and

appropriately understand the consequences of those differences. Guidelines for addressing differences

can be found in FAA AC 120-53 and FSB reports applicable to a particular type.

7.2.6. Category III Operations with an Inoperative Engine. For air carriers authorized to initiate

a Category III approach with an inoperative engine either through Category III dispatch or equivalent

procedures or for engine failures which occur en route, appropriate training should be completed to

assure that pilots and aircraft dispatchers can properly apply the provisions of section 10.8. For airlines

that do not authorize the initiation of a Category III approach with an engine inoperative as an approved

procedure, pilots should at least be familiar with the provisions of sections 10.8.4 and 10.8.5 regarding

an engine failure after passing the final approach fix. Additionally, pilots should be made aware of the

engine inoperative capabilities of the aircraft by reference to the AFM.

7.2.7. Training in Conjunction with Advanced Qualification Programs (AQP) or Exemptions for

“Single Visit Training.” Appropriate re-qualification or recurrent qualification programs may be

adjusted as necessary when incorporated in AQP or other single visit training programs. With such

programs, however, each of the areas of knowledge specified by section 7 of this AC must be assured.

7.2.8. Credit for "High Limit Captains" (Reference section 121.562). When authorized by the

POI, credit for high landing weather minimum limits and required turbojet experience may be authorized

consistent with provisions of exemptions authorized for Category III qualification credit.

7.2.9. Enhanced or Synthetic Vision Systems (Independent Landing Monitor). Training

required for enhanced or synthetic vision systems may be as specified by FAA based on successful

completion of proof of concept testing.

7.3. Checking or Evaluations. For both initial qualification and recurrent qualification, crewmembers

should demonstrate proper use of aircraft systems and correct procedures as follows, unless otherwise

specified by an applicable FSB report.

1. For automatic systems, for landing at least one automatic landing to a full stop, and one goaround from a low approach at, or after, decision or Alert Height. The automatic landing to a full stop

may be waived for recurrent qualification if the crewmember has accomplished an automatic landing

within a period for autoland currency for that operation and aircraft type.

2. For manual systems one landing to a complete stop at the lowest applicable minima and one goaround from low altitude below Alert Height or Decision Height and at least one response to a failure

condition during the approach to a landing or a missed approach should be demonstrated.
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3. For takeoff below RVR500, pilots should successfully demonstrate one takeoff in the event of

an engine failure at, or after, V1 and one rejected takeoff with an engine failure or other appropriate

failure near but prior to, V1.

7.4. Experience with Line Landings. When a qualification program has been completed using only a

simulator program, at least the following experience should be required before initiating Category III

operations, unless otherwise specified by an applicable FSB report.

1. For automatic systems at least one line landing using the auto flight system approved for

Category III minima should be accomplished in weather conditions at or better than Category II, unless

a pilot's qualification has been completed in a Level C or D simulator found acceptable for that autoland

system.

2. For manual systems such as head-up flight guidance system, the pilot in command must have

completed at least ten line landings, using the approved flight guidance system in the configuration

specified for Category III and at suitable facilities (e.g., facilities having appropriate ground facilities for the

lowest minima authorized, or equivalent).

7.5. Crew Records. The operator should assure that records suitably identify initial and continued

eligibility of pilots for Category III operations. Records should note the appropriate completion of

training for both ground qualification, flight qualification, and initial training, recurrent training, or requalification training, as applicable.

7.6. Dual Qualification. In the event that crewmembers are dual qualified as either captain or first

officer for checking and performing the duties of the second in command or for crewmembers dual

qualified between several aircraft types or variants, appropriate training and qualification must be

completed to assure that each crewmember can perform the assigned duties for each seat position and

each aircraft type or variant.

For programs involving dual qualification, principal inspectors should approve the particular operators

program considering the degree of differences involved in the Category III aircraft systems, the assigned

duties for each crew position and criteria such as AC 120-53 related to differences. If a pilot serving as

second in command is not expressly restricted from performing the duties of the pilot in command during

Category III approaches or low visibility takeoffs below RVR500, then that pilot must satisfactorily

complete the requirements for a pilot in command regarding maneuvers specified in section 7.2.

7.7. Interchange. When aircraft interchange is involved between operators, flightcrew members and

aircraft dispatchers must receive sufficient ground and flight training to assure familiarity and competency

with respect to the particular aircraft system or systems of the interchange aircraft. Guidelines for

differences should be consistent with those specified in AC 120-53 and FSB reports.
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7.8. Training For Use of Foreign Airports for Category III Operations or Low Visibility

Takeoff. Operators authorized to conduct Category III operations or low visibility takeoffs below

RVR600 at foreign airports, which require procedures or limitations different than those applicable

within the United States, should assure that flightcrew members and aircraft dispatchers are familiar with

any differences appropriate to operations at those foreign airports.

7.9. Line Checks. Operators should include assessments of Category III procedures and practices as

necessary during line checks when operations are conducted at facilities appropriate for Category III or

at facilities appropriate for simulating Category III operations.

8. AIRPORTS, NAVIGATION FACILITIES AND METEOROLOGICAL CRITERIA. United

States and non-United States airports and runways for Category III are those either having published part

97 SIAPS, or as otherwise specified on the FAA AFS-400 "Category II/Category III status checklist"

(FAA Order 8400.8). Requests for authorization to use other airports/runways should be coordinated

with AFS-400, through the operator's Certificate Holding District Office (CHDO).

8.1. Use of Standard Navigation Facilities. Category III operations may be approved on standard

United States or ICAO navigation facilities as follows:

United States Type 3 ILS facilities for which part 97 Category III procedures are published;

United States Type 2 ILS facilities for which a published part 97 Category III procedure has been

established;

Other United States Type 3 or Type 2 ILS facilities determined acceptable by AFS-400 for the type of

aircraft equipment and minima sought; and

Non-United States facilities meeting ICAO criteria (ICAO Annex 10, ICAO Manual of All Weather

Operations DOC 9365/AN910, etc.) and which are promulgated for use for Category III by the "State

of the Aerodrome."

8.2. Use of Other Navigation Facilities or Methods. Category III operations may be approved

using other types of navigation facilities than ILS or using other acceptable position fixing and integrity

assurance methods, if proof of concept demonstrations acceptable to FAA are successfully completed:

Other United States facilities approvable for Category III (MLS, GLS, DGPS, or a Type I ILS used in

conjunction with an acceptable aircraft integrity assurance system, etc.) are as determined acceptable by

AFS-400, and

Non-United States ILS facilities meeting acceptable criteria other than ICAO (e.g., JAA), may be used

as determined to be acceptable by AFS-400.
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8.3. Lighting Systems. Lighting used for Category III must include the following systems, or ICAO

equivalent systems, unless approved by AFS-400 (e.g., for Non-United States airports):

United States Standard ALSF1 or ALSF2 approach lights;

United States Standard Touchdown Zone Lights;

United States Standard Runway Centerline Lights;

United States Standard High Intensity Runway Lights;

United States Standard taxiway centerline lights (for any areas of the airport determined to be critical in an

FAA accepted Surface Movement Guidance and Control (SMGC) plan), or equivalent;

United States Standard taxiway edge lights (for taxiways not requiring centerline lights);

Suitable ramp and gate area lighting for low visibility operations (for night operations); and

Runway Hold line/Stop Bar lights (if applicable to a FAA approved SMGC plan).

Exceptions to the above lighting criteria may be authorized only if equivalent safety can be demonstrated

by an alternate means (e.g., substitution for required approach lighting components due to an approved

aircraft system providing equivalent information or performance [such as radar based EVS], or

redundant, high integrity, computed runway centerline information, displayed on a HUD).

8.4. Marking and Signs. Airports approved for Category III operations must include the following

runway and taxiway markings and airport surface signs, or ICAO equivalent, unless approved by AFS400 (e.g., for Non-United States airports):

United States Standard Precision Instrument Runway Markings.

United States Standard Taxiway edge and centerline Markings.

Runway signs, taxiway signs, hold line signs, taxiway reference point markings (if required by SMGC),

and NAVAID (ILS) critical area signs and markings.

Markings and signs must be in serviceable condition, as determined by the operator or FAA Certificate

Holding District Office (CHDO). Markings or signs found in an unacceptable condition by an operator

should be reported to the appropriate airport authority and CHDO. Operators should discontinue

Category II use of those areas of airport facilities or runways where unsafe conditions are known to exist

due to markings or signs being inadequate, until remedial actions are taken by the airport authority (e.g.,

snow removal, rubber deposit removal on runway touchdown zone markings or centerline markings,

critical area hold line or runway centerline marking repainting, runway hold line sign snow removal).
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8.5. Low Visibility Surface Movement Guidance and Control (SMGC) Plans. United States

airports conducting takeoff or landing operations below RVR1200 are required to develop a Surface

Movement Guidance and Control System (SMGCS) plan. SMGCS operations facilitate low visibility

takeoffs and landings and surface traffic movement by providing procedures and visual aids for taxiing

aircraft between the runway(s) and apron(s). Specific low visibility taxi routes are provided on a

separate SMGCS airport chart. SMGCS operations also facilitate the safety of vehicle movements that

directly support aircraft operations, such as aircraft rescue and fire fighting (ARFF) and follow-me

services, towing and marshaling.

Advisory Circular 120-57 as amended describes the standards and provides guidance in implementing

SMGCS operations such as aircrew training, etc. An operator intending authorization for Category III

operations should coordinate with the airport authority regarding their SMGCS plan. Equivalent

coordination is also applicable at non-U.S. airports if such a plan is used by that airport.

8.6. Meteorological Services and RVR Availability and Use.

8.6.1. Meteorological Services. Appropriate meteorological service (e.g., RVR, Altitude Settings,

METAR’s, TAF’s, Braking Action, NOTAM’s, reports) are necessary for each airport/runway

intended for use by an operator for Category II, unless otherwise approved by AFS-400. Non-United

States facilities should meet criteria of ICAO Doc 9365/AN910, second edition, or later, as amended.

This information must be readily available to both the crew and the aircraft dispatcher.

8.6.2. RVR Availability and Use.

8.6.2.1. RVR Availability. RVR availability for touchdown zone (TDZ), mid runway (MID), and

ROLLOUT RVR (or a corresponding international equivalent location) are as follows. RVR should be

provided for any runway over 8000 ft. in length. TDZ and ROLLOUT RVR should be provided for

runways less than 8000 ft. Exceptions to this availability for United States operators at international

locations may be approved on a case by case basis, by AFS-400, if equivalent safety can be

established. Factors considered due to local circumstances at non-United States airports may include

such issues as minima requested, characteristics of prevailing local weather conditions, location of RVR

sites or RVR calibration, availability of other supporting weather reports on nearby runways, etc.

8.6.2.2. RVR Use. RVR use by operators and pilots is as specified in standard operations

specifications Part C (see Appendix 7).

However, when approved as an exception in operations specifications, aircraft capable of certificated

landing or takeoff distance of less than 4000 ft. may be approved to use a single TDZ, MID, or

ROLLOUT transmissiometer as applicable to the part of the runway used (e.g., "Relevant" RVR). For

such operations, transmissiometers not used are considered to be optional and advisory, unless the aircraft

operation is planned to take place at a speed above safe taxi speed on the part of the runway where the

MID or ROLLOUT transmissiometer is located.
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For operations in the U.S., RVR must be instrumentally derived. At non-U.S. airports, RVR reports

that are not instrumentally derived may be used if their basis is determined to be reliable and accurate by

the operator and CHDO/POI.

For operations outside the U.S., operators and pilots should be familiar with any application and unique

use of RVR at the airports to be used. This should include any differences is standard reporting,

calibration, or RVR readings related to lighting step settings used, and any conversions necessary to be

made (e.g., meteorological visibility to RVR conversion).

For meteorological visibility to RVR conversion, when operating at foreign airports where the landing

minimums are specified only in RVR, and meteorological visibility is provided, the certificate holder or

pilot should convert meteorological visibility to RVR by multiplying the reported visibility by an

appropriate factor, as shown in Standard Operations Specifications

(see Appendix 7, Part C, Paragraph C051 for use of an appropriate conversion table). However, the

conversion of reported Meteorological Visibility to RVR provided in paragraph C051 should not be

used for takeoff minima or Category III minima, or when a reported RVR is available.

8.6.3. Pilot Assessment of Takeoff Visibility Equivalent to RVR. In special circumstances,

provision may be made for pilot assessment of takeoff visibility equivalent to RVR to determine

compliance with takeoff minima. Authorization for pilot assessment is provided through operations

specifications paragraph C078 (see Appendix 7) when a satisfactory procedure is provided to the

flightcrew. A pilot may assess visibility at the take off position in lieu of reported TDZ RVR (or

equivalent) in accordance with the following:

1. TDZ RVR is inoperative, or is not reported (e.g., ATS facility is closed), or

2. local visibility conditions as determined by the pilot indicate that a significantly different visibility

exists than the reported RVR (e.g., patchy fog, blowing snow, RVR believed to be inaccurate due to

snow cover or ice), and

3. pertinent markings, lighting, and electronic aids are clearly visible and in service (e.g., no

obscuring clutter), and

4. a pilot assessment is made using an accepted method regarding identification of an appropriate

number of centerline lights, or markings, of known spacing visible to the pilot when viewed from the

flight deck when the aircraft is at the take-off point, and

5. pilot assessment of visibility as a substitute for TDZ (takeoff) RVR is approved for the operator,

and observed visibility is determined to be greater than the equivalent of RVR300 (75m), and

6. a report of the pilot's determination of visibility (PIREP) is forwarded to a suitable ATS facility,

and if applicable, dispatch facility prior to departure (e.g., if an ATS facility or dispatch facility is
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applicable, available, pertinent, and is providing services relevant to the pilot report). A report of pilot

visibility is intended to provide information for other operations.

8.7. Critical Area Protection. Airports and runways used for Category II or III must have suitable

NAVAID (e.g., ILS) critical area protection, as applicable to the ground and aircraft systems used.

Procedures equivalent or more stringent than those specified in the Air Traffic Control Handbook (FAA

Order 7110.65) as amended, are required. Procedures consistent with ICAO DOC 9365/AN910 are

acceptable for non-United States facilities. Where uncertainty regarding acceptability of non-United

States airport procedures is a factor, operators or CHDOs should contact AFS-400 (e.g., for non

United States airports and runways listed on the FAA Category II/Category III status checklist where

doubt exists regarding adequacy of procedures encountered in routine operations) for follow up.

8.8. Operational Facilities, Outages, Airport Construction, and NOTAM’s. For operations to

be initially authorized, operations to continue to be authorized, for an aircraft to be dispatched with the

intention of using a facility described above, or for an aircraft to continue to its destination or an alternate

with the intent of completing a Category III instrument approach procedure, each of the applicable

necessary components or services identified in 8.1 through 8.7 above must be operating, available, or

normal as intended for Category III (e.g., NAVAID’s, standby power, lighting systems) except as

specified below.

Outer, Middle, or Inner Marker beacons may be inoperative unless a Category III operation is predicated

on their use (e.g., an AH is predicated on use of an Inner Marker due to irregular terrain, or the aircraft

system requires use of a marker beacon for proper flight guidance function).

Lighting systems are in normal status except that isolated lights of an approach light, or runway light

system may be inoperative; approach light components not necessary for the particular operation (such

as REIL, VASI, RAIL, or SFL) may be inoperative; lights may not be completely obscured by snow or

other such contaminants if necessary for the operation (e.g., night); Taxiway, ramp, and gate area

lighting components may be inoperative if not essential for the operation to be conducted.

Ground facility standby power capability for the landing airport or alternate (if applicable) must be

operative at the time of the aircraft's departure to a Category III destination or alternate.

Category III operations may be continued at airports at which construction projects affect runways,

taxiways, signs, markings, lighting, or ramp areas only if the operator has determined that low visibility

operations may be safely conducted with the altered or temporary facilities that are provided. In the

event of uncertainty as to the suitability of facilities, the operator should consult with their CHDO.

Operators may make the determination as to the suitability of the above facilities regarding unusual

weather or failure conditions unless otherwise specified by the airport authority, or FAA.

NOTAM’s for NAVAID’s, facilities, lighting, marking, or other capabilities must be appropriately

considered for both dispatch, and for continued flight operations intending to use a Category III

procedure. Operators, aircraft dispatchers, and pilots must appropriately respond to NOTAM’s
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potentially adversely affecting the aircraft system operation, or the availability or suitability of Category III

procedures at the airport of landing, or any alternate airport intended for Category III.

An operator may make the determination that a NOTAM does not apply to the aircraft system and

procedures being used for a particular flight if the safety of the operation can be ensured, considering the

NOTAM and situation (e.g., a NOTAM specifying Category III Not Available due to the ALS

inoperative, for an aircraft that had previously been dispatched based on a Category III ETOPS or

EROPS alternate airport flight plan, and no other suitable airport facility is available). In such instances,

pilots must be advised of any relevant information to the decision, and any precautions to be taken.

8.9. Use of Military Facilities. Military facilities may be used for Category III if authorized by DoD,

and if equivalent criteria are met as applicable to United States civil airports.

8.10. Special Provisions for Facilities Used for ETOPS or EROPS Alternates. ETOPS

operations are extended range operations with twin-engine aircraft, typically conducted over oceanic or

remote areas (see Appendix 1 for definitions, or see a current version of AC 120-42 and 14 CFR

section 121.161 for requirements or criteria). EROPS operations are those “extended range

operations” typically conducted in oceanic or remote areas, regardless of the number of installed

engines.

An airport used as an ETOPS or EROPS alternate based on having available Category III engineinoperative capability should meet at least the following criteria:

Sufficient information about pre-threshold terrain, missed approach path terrain, and obstructions should

be available so that an operator can assure that a safe Category III landing can be completed, and that

an engine-inoperative missed approach can be completed from AH or DH as applicable, or at any time

after passing the AH or DH at least to a point at the end of the landing touchdown zone (TDZ).

Sufficient meteorological and facility status information should be available so that a diverting flightcrew

and the aircraft dispatcher can receive timely status updates on facility capability, weather/RVR, wind

components, and braking action reports (if applicable), if conditions could or would adversely affect a

planned Category III landing during the period of a diversion.

For any alternate airports not routinely used by that operator as a regular destination airport

(e.g., EGCC as an alternate for EGLL; BIKF as a North Atlantic alternate), sufficient information

should be provided for aircraft dispatchers and pilots to be familiar with relevant low visibility and

adverse weather characteristics of that airport that might have relevance to an engine-inoperative

operation (e.g., unique lighting or markings, any nearby obstructions or frequently encountered local

wind shear or turbulence characteristics, meteorological reports, braking reports, and NOTAM

interpretation, appropriate ground taxi route and gate location information, emergency services

available).
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8.11. Alternate Minima. Use of alternate minima are specified in Standard OpSpecs Part C

paragraph C055. For applicability of "engine inoperative Category III" capability see section 10.8, and in

particular, 10.8.2 items (10) and (11).

Paragraph C055 is issued to all part 121 and part 135 operators who conduct IFR operations with

airplanes. This paragraph provides a three-part table from which the operator, during the initial dispatch

or flight release planning segment of a flight, determines applicable alternate airport IFR weather

minimums for those cases where it has been determined that an alternate airport is required.

a. Standard Provisions. Standard provisions of the Part C paragraph C055 operationspecification are applicable to airports with at least one operational navigational facility, or for multiple

navigation facilities providing straight-in instrument approach procedures other than precision, or a

straight-in precision approach procedure, or a circling maneuver from an instrument approach

procedure. The required ceiling and visibility is obtained by adding an increment to the landing minima

(e.g., adding 400 ft. to the Category I HAT or, as applicable, the authorized HAA, and by adding 1

statute mile to the authorized landing visibility.

b. Special Engine Inoperative Provisions. Special provisions for Category II and Category III

engine-out capability are listed in the third part of the table for airports with at least two operational

navigational facilities, each providing a straight-in precision approach, including a precision approach

procedure to Category II or Category III minima. The required ceiling and visibility for this operational

credit is obtained by adding 300 ft. or 200 ft. to the respective lowest Category II or Category III

touchdown zone elevation of the two approaches considered, and by adding 1200 ft. to the lowest

authorized RVR minimum (see Appendix 7 Part C paragraph C055).

8.12. Flight Planning to Airports That Have Weather Conditions Below Landing Minima. In

certain instances an operator may flight plan (e.g., dispatch) an aircraft to a destination airport even

though current weather is reported to be below, or may be forecast to be below landing minima. This is

to permit aircraft to begin a flight if there is a reasonable expectation that at or near the expected time of

arrival at the destination airport, weather conditions are expected to permit a landing at or above landing

minima.

Flight Planning (e.g., dispatch) to such airports typically is considered acceptable if the following

conditions are met:

1) All requirements are met to use the landing minima at the destination and at each alternate airport on

which the flight plan (e.g., dispatch) is predicated (e.g., aircraft, crew, airport facilities, NAVAID’s).

2) If Alternate minima credit is applied based on availability of Category III capability, or Engine

inoperative Category III capability, then each of the airborne systems otherwise applicable to use of that

capability must be available at the time of flight planning (e.g., flight guidance system, anti skid, thrust

reverse capability, as applicable to the aircraft type and Category III authorization for that operator)
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3) ETA at the destination airport considers any necessary holding fuel that may be required while the

aircraft waits for weather improvement.

4) Air Traffic conditions are considered for potential delay due to other aircraft arrivals or departures at

the destination and at each alternate airport.

5) At least two qualifying alternates are available, the first of which considers the aircraft flying to the

below minima intended destination, then holding for a time as determined by the operator awaiting

approach or weather improvement, then flying to the closest alternate, then completing an approach and

missed approach at that airport, and then flying to the second alternate and landing with appropriate

reserve fuel.

9. CONTINUING AIRWORTHINESS/MAINTENANCE.

9.1. Maintenance Program. Unless otherwise approved by FAA, each operator should have an

approved continuous airworthiness maintenance program (CAMP). The approved continuous

airworthiness maintenance program should typically include any necessary provisions to address lower

landing minima (LLM) or low visibility takeoff in accordance with the operator’s intended operation and

the manufacturers recommended maintenance program, MRB requirements or equivalent requirements,

or any subsequent FAA designated requirements (e.g., AD’s, mandatory service bulletins). Emphasis

should be on maintaining and ensuring total system performance, accuracy, availability, reliability, and

integrity for the intended operations.

9.2. Maintenance Program Provisions. The maintenance program should be compatible with an

operator’s organization and ability to implement and supervise the program. Maintenance personnel

should be familiar with the operators approved program, their individual responsibilities in accomplishing

that program, and availability of any resources within or outside of the maintenance organization that may

be necessary to assure program effectiveness (e.g., getting applicable information related to the

manufacturer’s recommended maintenance program, getting information referenced in this AC such as

service bulletin information).

Provision for low visibility operations may be addressed as a specific program or may be integrated with

the general maintenance program.

Regardless whether the maintenance program is integrated or is designated as a specific program for

Lower Landing Minima (LLM), the maintenance program should at least address the following:

1) Maintenance procedures necessary to ensure continued airworthiness relative to low visibility

operations.

2) A procedure to revise and update the maintenance program.
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3) A method to identify, record or designate personnel currently assigned responsibility in managing

the program, performing the program, maintaining the program, or performing quality assurance for the

program. This includes identification of any contractor or sub-contractor organizations, or where

applicable, their personnel.

4) Verification should be made of the lower landing minima systems and configuration status for

each aircraft brought into the maintenance or lower minimum program. Unless otherwise accepted by

FAA, each aircraft should meet relevant criteria specified by the applicable aircraft manufacturer or

avionics manufacturer for associated systems and equipment (e.g., Valid U.S. TC, appropriate STC

records and compliance, assessment of status of any engineering orders, AD’s, service bulletins or other

compliance).

5) Identification of modifications, additions, and changes which were made to qualify aircraft systems

for the intended operation or minima, if other than as specified in the AFM, TC or STC.

6) Identification of additional maintenance requirements and log entries necessary to change minima

status.

7) Any discrepancy reporting procedures that may be unique to the low visibility program. If

applicable, such procedures should be compatibly described in maintenance documents and operations

documents.

8) Procedures which identify, monitor and report lower minimum system and component

discrepancies for the purpose of quality control and analysis.

9) Procedures which define, monitor and report chronic and repetitive discrepancies.

10) Procedures which ensure aircraft remain out of lower minimum status until successful corrective

action has been verified for chronic and repetitive discrepancies.

11) Procedures which ensure the aircraft system status is placarded properly and clearly

documented in the aircraft log book, in coordination with maintenance control, engineering, flight

operations, and dispatch, or equivalent.

12) Procedures to ensure the downgrade of an aircraft low visibility capability status, if applicable,

when maintenance has been performed by persons other than those trained, qualified, or authorized to

use or approve procedures related to low visibility operations.

13) Procedures for periodic maintenance of systems ground check, and systems flight check, as

applicable. For example, following a heavy maintenance, suitable checks may need to be performed

prior to return to service.
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14) Provisions for an aircraft to remain in a specific low visibility capability status (e.g., Category II,

Category III, Fail-Operational, Fail Passive) or other designated operational status used by the

operator.

15) Provision should be made for periodic operational sampling of suitable performance. Typically,

at least one satisfactory approach should have been accomplished within a specified period approved

for that operator, unless a satisfactory systems ground check has been accomplished. A recording

procedure for both satisfactory and unsatisfactory results should be included. Fleet sampling is not

typically acceptable in lieu of specific aircraft assessment. Typically at least one satisfactory low

visibility system operational use, or a satisfactory systems ground check, should be accomplished within

30 days, for an aircraft to remain in Category III status. Any extension to an aircraft sampling period

limit beyond 30 days, or use of statistical fleet sampling should be consistent with the manufacturer’s

current sampling recommendations and be based on the demonstrated reliability of that operator’s

aircraft flight guidance system performance in service. Failure of an operator to maintain an acceptable

reliability record should result in timely and appropriate remedial action, and should lead to

reconsideration of suitability of any sampling period extensions or fleet statistical sampling authorizations.

9.3. Initial And Recurrent Maintenance Training. Operator and contract maintenance personnel

including mechanics, maintenance controllers, avionics technicians, personnel performing maintenance

inspection or quality assurance, or other engineering personnel if applicable, should receive initial and

recurrent training as necessary for an effective program. The training curriculum should include specific

aircraft systems and operator policies and procedures applicable to low visibility operations. Recurrent

training should typically be accomplished at least annually, or when a person has not been involved in the

maintenance of the specified aircraft or systems for an extended period (e.g., greater than 6 months).

Training may lead to a certification or qualification (e.g., for lower landing minima “LLM”) if the operator

so designates such qualification in that operator’s approved program.

The training should at least include, as applicable:

1) An initial and recurrent training program for appropriate operator and contract personnel.

Personnel considered to be included are maintenance personnel, quality and reliability groups, maintenance

control, and incoming inspection and stores, or equivalent organizations. Training should include both

classroom and at least some “hands-on” aircraft training for those personnel who are assigned aircraft

maintenance duties. Otherwise, training may be performed in a classroom, by computer based training, in

simulators, in an airplane or in any other effective combination of the above consistent with the approved

program, and considered acceptable to FAA.

2) Subject areas for training should include: Operational concepts, aircraft types and systems

affected, aircraft variants and differences where applicable, procedures to be used, manual or technical

reference availability and use, processes, tools or test equipment to be used, quality control, methods

for testing and return to service, signoffs required, proper Minimum Equipment List (MEL) application,

general information about where to get technical assistance as necessary, necessary coordination with
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other parts of the operator’s organization (e.g., flight operations, dispatch), and any other maintenance

program requirements unique to the operator or the aircraft types or variants flown (e.g., human factors

considerations, problem reporting).

3) Procedures for the use of outside vendors or vendor’s parts that ensures compatibility to

program requirements and for establishing measures to control and account for parts overall quality

assurance.

4) Procedures to ensure tracking and control of components that are “swapped” between systems

for trouble shooting when systems discrepancies can not be duplicated. These procedures should

provide for total system testing and/or removal of aircraft from lower minimum status.

5) Procedures to assess, track and control the accomplishment of changes to components or

systems pertinent to low visibility operations (e.g., AD’s, service bulletins, engineering orders, FAR

requirements).

6) Procedures to record and report lower minimum operation(s) that are discontinued/ interrupted

because of system(s) malfunction.

7) Procedures to install, evaluate, control, and test system and component software changes,

updates, or periodic updates.

8) Procedures related to the minimum equipment list (MEL) remarks section use which identify low

visibility related systems and components, specifying limitations, upgrading and downgrading.

9) Procedures for identifying low visibility related components and systems as “required inspection

items” (RII), to provide quality assurance whether performed in-house or by contract vendors.

9.4. Test Equipment/Calibration Standards. Test equipment may require periodic re-evaluation to

ensure it has the required accuracy and reliability to return systems and components to service following

maintenance. A listing of primary and secondary standards used to maintain test equipment which relate

to low visibility operations should be maintained. It is the operator’s responsibility to ensure these

standards are adhered to by contract maintenance organizations. Traceability to a national standard or

the manufacturer’s calibration standards should be maintained.

9.5. Return To Service Procedures. Procedures should be included to upgrade or downgrade

systems status concerning low visibility operations capability. The method for controlling operational

status of the aircraft should ensure that flightcrews, maintenance and inspection departments, dispatch,

and other administrative personnel as necessary are appropriately aware of aircraft and system status.

The appropriate level of testing should be specified for each component or system. The manufacturer’s

recommended maintenance program or maintenance instructions should be considered when
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determining the role built-in-test-equipment (BITE) should play for return to service (RTS) procedures,

or for use as a method for low visibility status upgrade or downgrade.

Contract facilities or personnel should follow the operator’s FAA approved maintenance program to

approve an aircraft for return to service. The operator is responsible for ensuring that contract

organizations and personnel are appropriately trained, qualified, and authorized.

9.6. Periodic Aircraft System Evaluations. The operator should provide a method to continuously

assess or periodically evaluate aircraft system performance to ensure satisfactory operation for those

systems applicable to Category II or III. An acceptable method for assuring satisfactory performance of

a low visibility flight guidance system (e.g., autoland or HUD) is to periodically use the system and note

satisfactory performance. A reliable record such as a logbook entry or computer ACARS record

showing satisfactory performance within the previous 6 months for Category II, or previous 30 days for

Category III, is typically an acceptable method for assuring satisfactory system operation (see Section 9.2

item 15).

Periodic flight guidance system/autoland system checks should be conducted in accordance with

procedures recommended by the airframe or avionics manufacturer, or by an alternate procedure

approved by the FAA. For periodic assessment, a record should be established to show when and

where the flight guidance/autoland system was satisfactorily used, and if performance was not

satisfactory, to describe any remedial action taken.

Use of the flight guidance/automatic landing system should be encouraged to assist in maintaining its

availability and reliability.

9.7. Reliability Reporting And Quality Control. For a period of 1 year after an applicant has been

authorized reduced minima, a monthly summary should be submitted to the certificate holding office.

The following information should be reported:

a. The total number of approaches tracked, the number of satisfactory approaches tracked, by

aircraft/system type, and visibility(RVR), if known or recorded.

b. The total number of unsatisfactory approaches, and reasons for unsatisfactory performance, if

known, listed by appropriate category(e.g., poor system performance, aircraft equipment problem/failure;

ground facility problem, ATS handling, lack of critical area protection, or other).

c. The total number of unscheduled removals of components of the related avionics systems.

d. Reporting after the initial period should be in accordance with the operators established reliability

and reporting requirements.

9.8. Configuration Control/System Modifications. The operator should ensure that any

modification to systems and components approved for low visibility operations are not adversely
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affected when incorporating software changes, service bulletins, hardware additions or modifications.

Any changes to system components should be consistent with the aircraft manufacturer’s, avionics

manufacturer’s, industry or FAA accepted criteria or processes.

9.9. Records. The operator should keep suitable records (e.g., both the operator's own records and

access to records of any applicable contract maintenance organization). This is to ensure that both the

operator and FAA can determine the appropriate airworthiness configuration and status of each aircraft

intended for Category III operation.

Contract maintenance organizations should have appropriate records and instructions for coordination

of records with the operator.

9.10. FAR 129 Foreign Operator Maintenance Programs.

9.10.1. Maintenance of FAR 129 Foreign Registered Aircraft. For part 129 operators of

Foreign registered aircraft (e.g., section 129.14 is not applicable), the cognizant CAA is the CAA of

the operator. For those situations, FAA may implicitly accept that the maintenance program is

considered to be acceptable if the cognizant CAA has approved it, and if the operator or CAA

indicates that the program meets U.S. criteria, U.S. equivalent criteria (e.g., criteria such as JAA

criteria), or ICAO criteria (e.g., Annex 6 and Doc 9365/AN910 "Manual of All Weather

Operations"), and the cognizant CAA has authorized Category II or Category III U.S. operations.

FAA then issues the pertinent part 129 Category II/III OpSpec based on the other CAA’s approval

for that operator. However, FAA reserves the prerogative to assure competence of both the operator

and authorizing and supervising CAA, depending on whether the CAA or operator are considered to

be from a category 1, 2, or 3 country (safety classification not a low visibility landing classification), and

if there have been any reported problems with the operator or CAA. Evidence of the operator

satisfying or being consistent with the manufacturer's recommended maintenance program should serve

as evidence of an acceptable maintenance program, regardless of the capability of the CAA or the

operator, unless FAA has specifically addressed maintenance requirements beyond those of the

manufacturer for that aircraft type (e.g., required service bulletin compliance or Airworthiness Directive

compliance related to the flight guidance system).

9.10.2. Maintenance of FAR 129 Foreign Operated U.S. “N” Registered Aircraft. Foreign

operators of U.S. "N" Registered Aircraft (e.g., those operators to which section 129.14 is

applicable) should have maintenance programs equivalent to that required for a U.S. part 121

operator. Use of the part 91 provisions for General Aviation are not applicable or appropriate.

Principal Operations Inspector Approval of Category II/III OpSpecs for a part 129.14 operator

may implicitly be considered to also accept the maintenance program adequacy. Accordingly,

coordination between the applicable POI and PMI is necessary before part 129 OpSpec

authorization is completed. The FAA is ultimately the cognizant CAA for the maintenance program

in this instance, if the aircraft is N registered. The FAA may however, accept the oversight of the

operators CAA if that CAA is judged by FAA to have equivalent processes, criteria and procedures

for oversight of maintenance programs (e.g., JAA countries). The basis for any such maintenance
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program should be the recommended airframe manufacturer (or avionics vendor) program,

considering any adjusted MRB requirements.

10. APPROVAL OF UNITED STATES OPERATORS.

Approval for Category I, II and III is through issuance of or amendments to Operations Specifications

(OpSpecs). The authorizations, limitations, and provisions applicable to Category I, Category II or

Category III are specified in Part C of the OpSpecs. Sample OpSpecs are provided in Appendix 7.

Operations specifications authorizing Category I operations that use ICAO standard NAVAID’s are

normally approved by the certificate holding district office or regional flight standards office without

further review and concurrence. All Category II or Category III operations normally require both

regional flight standards and AFS-400 review and concurrence before approval.

10.1. Operations Manuals and Procedures.

a. Manuals. Prior to Category approval, appropriate flightcrew operating manuals, flight manuals,

airline policy manuals, maintenance manuals, training manuals, and related aircraft checklists, quick

reference handbooks, or other equivalent operator information, should satisfactorily incorporate

pertinent Category III provisions.

Information covered in ground training, and procedures addressed in flight training should be available to

pilots in an appropriate form for reference use.

b. Procedures. Prior to Category approval, provisions of section 6 of this AC for procedures,

duties, instructions, or any other necessary information to be used by flightcrews and aircraft dispatchers

should be implemented by the operator.

Crew member duties during the approach, flare, rollout, or missed approach should be described.

Duties should at least address responsibilities, tasks of the pilot flying the aircraft and the pilot not flying

the aircraft during all stages of the approach, landing, rollout and missed approach. The duties of

additional crewmembers, if required, should also be explicitly defined.

Specification of crewmember duties should address any needed interaction with the aircraft dispatcher

or maintenance (e.g., addressing resolution of aircraft discrepancies and return to service).

The applicant's qualification program should incorporate specific Category II/III procedural

responsibilities for the pilot in command and second in command in each of the ground training subject

areas listed in paragraph 7.1, and each of the flight training subject areas listed in paragraph 7.2.

10.2. Training Programs and Crew Qualification. Training programs, AQP programs (if applicable),

crew qualification and checking provisions and standards, differences qualification (AC 120-53) if

applicable, check airmen qualification, line check, route check, and IOE programs should each
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satisfactorily incorporate necessary Category III provisions, as applicable (see sections 7.2 through 7.4).

An acceptable method to track pertinent crewmember Category III qualification and recency should be

established (see section 7.5).

For manually flown Category III systems (e.g., HUD FD’s, Hybrid HUD/Autoland) ensure that provisions

are made for each flightcrew member to receive the appropriate training, qualification, and line experience

before that particular crewmember is authorized to use the pertinent Category III minima.

10.3. Flight Planning (e.g., Dispatch, MEL, Alternate Airports, ETOPS or EROPS). MEL and

CDL provisions should be addressed, as necessary, for Category III operations. The flight planning

(e.g., pilot or aircraft dispatcher) should ensure appropriate consideration of reported and forecast

weather, field conditions, facility status, NOTAM information, alternate airport designation, engineinoperative missed approach performance, crew qualification, airborne system status, and fuel planning.

For ETOPS or EROPS operations, a satisfactory method to address item 8.10 above should be

demonstrated.

10.4. Formulation of Operations Specification (e.g., RVR limits, DH or AH, equipment, field

lengths). Proposed OpSpecs should list pertinent approved RVR limits, DH or AH use provisions,

"Inner Marker based DH or AH" provisions (if applicable), required transmissiometers,

airports/runways, aircraft equipment provisions for "normal" and, if applicable, "engine-inoperative"

operations, landing field length provisions, and any other special requirements identified by the CHDO

or AFS-400 (e.g., ETOPS or EROPS Category III). The operator's manuals, procedures, checklists,

QRH’s, MEL’s, dispatch procedures and other related flightcrew information should be shown to be

consistent with the proposed OpSpecs.

10.5. Operational/Airworthiness Demonstrations. Appropriate "airborne system suitability" and

"operational use suitability" demonstrations must be completed as described in sections 10.5.1 and

10.5.2, unless otherwise specified by AFS-400. The purpose of these operational demonstrations is to

determine or validate the use and effectiveness of the applicable aircraft flight guidance systems, training,

flightcrew procedures, maintenance program, and manuals applicable to the Category III program being

approved. Operators of aircraft having FAA approved AFM’s referencing AC 120-28D as the criteria

used as the basis for Category III airworthiness demonstration already are considered to meet provisions

of section 10.5.1, and typically need only address provisions of section 10.5.2. for verification of

operational use suitability.

10.5.1. Airborne System Suitability Demonstration. Low visibility takeoff and landing

requirements for Category I, Category II, and Category III are related to operating rules addressed by

Standard OpSpecs and 14 CFR parts 1, 61, 91, 97, 121, 125, and 135. These provisions apply

continuously, as defined at the time of a particular Category I, II, or III operation. Airworthiness rules

(14 CFR parts 23, 25, etc.,) primarily apply at the time a "certification basis" is established for type

certificate (TC) or supplemental type certificate (STC) and do not necessarily reflect "present"

requirements, except through issuance of AD’s updated with an amended type certificate or new STC
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application. Accordingly, operationally acceptable demonstrations addressing suitability of airborne

systems for Category III, as applicable, must be successfully completed initially, and acceptable system

status must be maintained by an operator to reflect compliance with current operating rules and

airworthiness requirements, to initially operate or continue to operate to Category III minima.

To minimize the need for repeating initial airborne system operational suitability demonstrations for each

operator, airborne system suitability is usually demonstrated in conjunction with airworthiness approval

(TC or STC) of airborne system components such as flight guidance systems, autoland, flight directors,

HUD’s, flight instrument and alerting systems, radio altimeters, inertial systems, and air data systems.

This approach to determination of airborne system suitability is taken to optimize use of analysis and

flight demonstration resources for operators, aircraft manufacturers, avionics manufacturers, and the

FAA. Accordingly, airborne system suitability is normally demonstrated through an initial airworthiness

demonstration meeting applicable provisions of Appendices to this AC (or combined

airworthiness/operational evaluation for new systems or concepts, or where otherwise necessary).

Demonstration to an acceptable earlier version of AC 120-28 or equivalent criteria may continue to be

used for demonstration of aircraft/airborne systems initially type certificated prior to issuance of this AC

120-28D revision as applicable to the particular aircraft or airborne system (e.g., current production

aircraft using earlier AC’s 120-28/A/B/C.)

However, previously demonstrated aircraft or airborne systems seeking Category III credits specified

only in provisions of revised AC 120-28D (e.g., Hybrid Autoland/HUD Category III) must meet

criteria specified in this AC.

Acceptable results of such airworthiness evaluations are usually described in section 3 (Normal and NonNormal Procedures) of the FAA approved AFM or AFM Supplement. Certificate Holding District

Offices should ensure that aircraft proposed for Category III have completed such an appropriate

airborne system operational suitability demonstration, and that result should normally be reflected in the

approved AFM or AFM Supplement, unless otherwise specified by AFS-400.

For aircraft certified by FAA through section 21.29 (Certain Non-United States manufactured aircraft),

AFM provisions applicable to Category III may vary. In certain instances AFM provisions may not be

consistent with United States policy or rules applicable to Category III. In such instances, CHDO prior

coordination with AFS-400 is appropriate to provide appropriate guidance to operators regarding

applicability of various AFM provisions (e.g., DH and RVR limitations, acceptable NAVAID use,

alerting system use, and required versus recommended crew procedures).

In the event of special circumstances such as FAA Category III acceptance of an aircraft certificated by

a Non-United States airworthiness authority which has only foreign AFM Category III approval, or

acceptance of additional credit for existing systems, operational assessments in accordance with criteria

in this AC, or equivalent criteria, may be necessary. In such instances, AFS-400 specifies applicable

criteria.
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10.5.2. "Operator Use Suitability" Demonstration. At least one-hundred (100) successful

landings should be accomplished in line operations using the low visibility landing system installed in each

aircraft type applicable to the Category III authorization. Demonstrations may be conducted in line

operations, during training flights, or during aircraft type or route proving runs.

If an excessive number of failures (e.g., unsatisfactory landings, system disconnects) occur during the

landing demonstration program, a determination should be made for the need for additional

demonstration landings, or for consideration of other remedial action (e.g., procedures adjustment, wind

constraints, or system modifications).

The system should demonstrate reliability and performance in line operations consistent with the

operational concepts specified in section 4. In unique situations where the completion of 100 successful

landings could take an unreasonably long period of time due to factors such as a small number of aircraft

in the fleet, limited opportunity to use runways having Category II/III procedures, or inability to obtain

ATS critical area protection during good weather conditions, and equivalent reliability assurance can be

achieved, a reduction in the required number of landings may be considered on a case-by-case basis.

Reduction of the number of landings to be demonstrated requires a justification for the reduction, and

prior approval from the Technical Programs Division (AFS-400).

Landing demonstrations should be accomplished on U.S. facilities or international facilities acceptable to

FAA which have Category II or III procedures. However, at the operator's option, demonstrations

may be made on other runways and facilities if sufficient information is collected to determine the cause

of any unsatisfactory performance (e.g., critical area was not protected). No more than 50 percent of

the demonstrations may be made on such facilities.

If an operator has different models of the same type of aircraft using the same basic flight control and

display systems, or different basic flight control and display systems on the same type of aircraft, the

operator should show that the various models have satisfactory performance, but the operator need not

conduct a full operational demonstration for each model or variant.

10.5.2.1. Data Collection For Airborne System Demonstrations. Each applicant should develop

a data collection method (e.g., form to be used by flightcrew) to record approach and landing

performance. Data should be collected whenever an approach and landing is attempted using the

Category III system, regardless of whether the approach is abandoned, unsatisfactory, or is concluded

successfully. The resulting data and a summary of the demonstration data should be made available to

the CHDO for evaluation. The data should, as a minimum, include the following information:

1. Inability to Initiate an Approach. Identify deficiencies related to airborne equipment which

preclude initiation of a Category III approach.

2. Abandoned Approaches. Give the reasons and altitude above the runway at which approach

was discontinued or the automatic landing system was disengaged.
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3. Touchdown or Touchdown and Rollout Performance. Describe whether or not the aircraft

landed satisfactorily (within the desired touchdown area) with lateral velocity or crosstrack error which

could be corrected by the pilot or automatic system so as to remain within the lateral confines of the

runway without unusual pilot skill or technique. The approximate lateral and longitudinal position of the

actual touchdown point in relation to the runway centerline and the runway threshold, respectively,

should be indicated in the report. This report should also include any Category III system abnormalities

which required manual intervention by the pilot to ensure a safe touchdown or touchdown and rollout,

as appropriate.

10.5.2.2. Data Analysis. Unsatisfactory approaches using facilities approved for Category II or III

where landing system signal protection was provided should be fully documented. The following factors

should be considered:

1. ATS Factors. ATS factors which result in unsuccessful approaches should be reported.

Examples include situations in which a flight is vectored too close to the final approach fix/point for

adequate localizer and glide slope capture, lack of protection of ILS critical areas, or ATS requests the

flight to discontinue the approach.

2. Faulty NAVAID Signals. NAVAID (e.g., ILS localizer) irregularities, such as those caused by

other aircraft taxiing, over-flying the NAVAID (antenna), or where a pattern of such faulty performance

can be established should be reported.

3. Other Factors. Any other specific factors affecting the success of Category III operations that

are clearly discernible to the flightcrew should be reported. An evaluation of reports discussed in

subparagraphs 10.5.2.1 (1), (2), and (3) will be made to determine system suitability for further

Category III operations.

10.5.2.3. Approval of Landing Minima. When the data from the operational demonstration has been

analyzed and found acceptable, an applicant may be authorized the lowest requested minima consistent

with this AC and applicable standard operations specifications. Several examples are provided below.

For Category III, fail passive operations where the operator was initially authorized RVR1000 (300 m)

to begin a demonstration program, following successful demonstration that operator may be authorized

to operate to minima of RVR600 (175 m).

For Category III fail operational operations, where the operator was initially authorized RVR1000 (300

m) to begin a demonstration program, following successful demonstration that operator may be authorized

to operate to minima of RVR600 (175 m) or RVR300 (75 m) as applicable.

If the Category III rollout control system has been shown to meet the appropriate provisions of Appendix

3, and the airborne and ground systems including applicable ILS, GLS or MLS (e.g., xLS), Surface

Movement Guidance and Control (SMGCS), and weather reporting (e.g., RVR) are each suitable, then

operations approvals for operations below RVR300 (75 m) may be authorized. Such authorizations are

considered only for specific facilities on a case by case basis, based on suitable and successful operational
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experience for each particular operator and aircraft type, and must have included actual operations in

weather conditions at or below RVR600, using minima of RVR300.

For additional examples of minima step down provisions acceptable to FAA see paragraphs 10.9 and

10.10.

10.6. Eligible Airports and Runways. An assessment of eligible airports, runways, and airborne

systems must be made in order to list appropriate runways on OpSpecs. Runways authorized for

particular aircraft in accordance with existing operations listed on the AFS-400 Category II/Category III

status checklist may be directly incorporated in OpSpecs, or incorporated by reference if published part

97 SIAPS are available. Aircraft type/runway combinations not shown should be verified by airborne

system use in line operations at Category II or better minima, prior to authorization for Category III.

Airports/aircraft types restricted due to special conditions (e.g., irregular underlying terrain) must be

evaluated in accordance with Appendix 8, prior to OpSpecs authorization.

If applicable, the operator should identify any necessary provisions for periodic demonstration of the

airborne system on runways other than those having Category II or III procedures (e.g., periodic autoland

performance verification, using runways served only by a Category I procedure).

A status checklist for facilities which have published Category II or III procedures can be viewed on the

Internet using the following address to access the FAA’s Flight Standards Service home page:

FAA Category II/Category III Status Checklist

http://www.faa.gov/avr/afshome.htm

To access this list, search the menu for Air Transportation and select All Weather Operations. The

desired section can then be selected from the All Weather Operations home page menu.

10.7. Irregular Pre-Threshold Terrain and Other Restricted Runways. Airports/runways with

irregular pre-threshold terrain, or runways restricted due to NAVAID or facility characteristics (see FAA

Category II/Category III Status Checklist in section 10.6) may require special evaluation, or limitations.

Certificate Holding District Offices (CHDO’s) of operators desiring operations on these runways should

contact AFS-400 to identify pertinent criteria and evaluation requirements. Various procedures used by

FAA to assess irregular pre-threshold terrain are described in Appendix 8.

10.8. Engine-Inoperative Operations and ETOPS or EROPS Alternates based on

Category III. Low visibility landing minima are typically based on normal operations. For non-normal

operations, flightcrews and aircraft dispatchers are expected to take the safest course of action to

resolve the non-normal condition. The low weather minima capability of the aircraft must be known and

available to the flightcrew and aircraft dispatcher.
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In certain instances, sufficient airborne system redundancy may be included in the aircraft design to

permit use of an alternate configuration such as “engine inoperative capability” for initiation of a

Category III approach. Use of an engine inoperative configuration is based on the premise that the

engine non-normal condition is an engine failure that has not adversely affected other airborne systems.

Systems which should be considered include systems such as hydraulic systems, electrical systems or

other relevant systems for Category III that are necessary to establish the appropriate flight guidance

configuration.

An alternate engine inoperative configuration also is based on the premise that catastrophic engine failure

has not occurred which may have caused uncertain, or unsafe collateral damage to the airframe, or

aerodynamic configuration.

In instances when AFM or operational criteria is not met, and a Category III approach is necessary,

because it is the safest course of action, (e.g., in flight fire), the flightcrew may use emergency authority.

The flightcrew should determine to the extent necessary the state of the aircraft and other diversion

options to ensure that an approach in weather conditions less than Category II is the safest course of

action.

Four cases are useful in considering engine inoperative Category III capability, and engine inoperative

approach authorization:

1. Flight planning (e.g., Dispatch) is based on aircraft configuration, reliability, and capability for

"engine inoperative Category III" (see Section 10.8.2).

2. An engine fails en route, but prior to final approach (see Section 10.8.3).

3. An engine fails during the approach after passing the final approach fix, but prior to reaching the

Alert Height or Decision Height (see Section 10.8.4).

4. An engine fails during approach after passing the Alert Height or Decision Height (see

Section 10.8.5).

Section 5.17 provides airworthiness criteria for demonstration of Category III engine out capability.

Sections 10.8.1 through 10.8.5 below address criteria for use of aircraft with "engine inoperative

Category III" capability.

10.8.1. General Criteria for Engine-Inoperative Category III Authorization. Aircraft capability

for "engine-inoperative Category III" should be approved in accordance with the provisions of

paragraph 5.17, and Appendix 3.

Regardless of whether an operator is or is not operationally authorized for "engine inoperative Category

III", it must be clear that having this aircraft capability should not be interpreted as requiring a Category
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III landing at the "nearest suitable" airport in time (e.g., does not require landing at the nearest suitable

Category III qualified airport - section 121.565).

POI’s should ensure that the following conditions are met:

1. Operations must be in accordance with the "engine inoperative Category III" AFM provisions

(e.g., within demonstrated wind limits, using appropriate crew procedures).

2. Demonstrated/acceptable configurations must be used (e.g., AFDS modes, flap settings,

electrical power sources, MEL provisions).

3. WAT limits must be established, and Engine-inoperative Missed Approach obstacle clearance

from the TDZ must be ensured. This data should be readily available for flight planning (e.g., to the

aircraft dispatcher) either by pre-determined certification listing or through appropriate engine-inoperative

programming in automated flight planning and performance systems.

4. Appropriate training program provisions for engine inoperative approaches must be provided

(see paragraph 7.2.6).

5. Pilots must be aware that they are expected to take the safest course of action, in their judgment,

in the event that unforeseen circumstances or unusual conditions occur that are not addressed by the

"engine-inoperative" Category III demonstrated configuration (e.g., uncertain aircraft damage, possible

fire, weather deterioration).

6. Operations Specifications must identify the type of "engine-inoperative" Category III operations

authorized. Types of operations are described in sections 10.8.2 through 10.8.5 below.

10.8.2. Engine Inoperative "Flight Planning." The operator (e.g., aircraft dispatcher) may

consider "engine inoperative Category III" capability in planning flights for a takeoff alternate, en route

(ETOPS or EROPS) alternate, re-dispatch alternate, destination, or destination alternate only if each of

the following conditions are met:

1. The operator (e.g., aircraft dispatcher) has determined that the aircraft is capable of engine

inoperative Category III.

2. Appropriate procedures, performance, and obstacle clearance information must be provided

to the crew to be able to safely accomplish an engine inoperative missed approach at any point in the

approach. If applicable, similar information must also be readily available to the aircraft dispatcher.

3. Appropriate operational weather constraints must be considered and specified as necessary

regarding cross wind, head wind, tail wind limits considering the demonstrated capability specified in the

AFM.
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4. Weather reports or forecast must indicate that specified alternate minimums or landing

minimums will be available for the runway equipped with approved Category III systems and

procedures. The operators use of engine inoperative capability credit should consider both the

availability and reliability of meteorological reports and forecasts, the time factors involved in potential

forecast accuracy, the potential for variability in the weather at each pertinent airport, and the ability for

the crew and, if applicable, aircraft dispatcher to obtain timely weather reports and forecast updates

during the time the flight is en route. Flight planning considerations must account for any expected ATS

delays that might be experienced during arrival due to weather, snow removal, or other factors.

5. Notices to airmen or equivalent information for airport and facility status should be reviewed

to ensure that they do not preclude the accomplishment of a safe engine inoperative approach on the

designated runway using approved Category III procedures (e.g., temporary obstructions). Any

change in NOTAM status of facilities related to use of landing minima or alternate minima must be

provided to the crew in a timely manner while en route.

6. If the engine inoperative configuration is different than a normal landing configuration, a means

to determine the landing distance of the section 121.195(b) distance must be available for the pertinent

engine inoperative aircraft configuration (e.g., landing flap setting). This distance is to ensure sufficient

runway to provide for any limitations on the use of reverse thrust or other factors that could pertain to an

inoperative engine landing (e.g., reduced flap settings used for an engine inoperative approach). This data

may be based on basic aircraft data otherwise available and need not be redemonstrated for "engine-out'

cases.

7. The expectation for runway surface condition based on pilot and operator (e.g., aircraft

dispatcher) interpretation of the available weather reports, field conditions, and forecasts is that the

applicable runway is likely to be free from standing water, snow, slush, ice, or other contaminants at the

time of landing. The flightcrew must be advised of any adverse change in this expectation while en

route.

8. Criteria otherwise applicable to "all engine" Category III, such as flightcrew or dispatcher

training, crew qualification, and availability of suitable procedures must also be addressed for the engine

inoperative landing case, if they are not the same as for the “all engine” case.

9. The operator is approved for operations based on engine inoperative Category III capability.

In addition, operator responsibilities for engine inoperative credit should be equivalent to that of current

normal operations when an en route landing system failure causes degraded landing capability. If an

inflight failure causes further degradation of engine inoperative landing capability, the flightcrew (if

applicable, in conjunction with the aircraft dispatcher) should determine an acceptable alternative course

of action (e.g., specification of different en route diversion options, revised fuel reserves plan, or revised

flight plan routing).

10. When engine inoperative Category III provisions are applied to identification of any

destination or destination alternate, more than one qualifying destination alternate is required. This is to
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provide for the possibility of adverse area wide weather phenomena, or unexpected loss of landing

capability at the first designated alternate airport.

11. An appropriate ceiling and visibility increment is added to the lowest authorized minimums

when credit for an alternate airport or airports is sought (e.g., 200 ft. DH additive and appropriate RVR

additive; see Appendix 7 - Operations Specification Example).

12. The airborne system should be shown through "in-service" performance that for fail-operational

systems, landing system availability is at least 99% from takeoff to 500’ HAT on approach, and for failpassive systems, system availability is at least 95% from takeoff to 500’ HAT on approach (see Appendix 3

section 6.5.1).

It should be noted that even if the aircraft, flightcrews, and operator are authorized for engine

inoperative Category III, flightcrews are not required to use a Category III approach to satisfy

requirements of section 121.565. Not withstanding section 121.565, pilots may elect to take a safe

course of action by landing at a more distant airport than one at which a Category III approach may be

required. Conversely, pilots may elect to conduct the Category III approach as the safest or a safe

course of action.

10.8.3. Engine Inoperative En Route. For engine failure en route, a pilot may initiate an "engine

inoperative" Category III approach under the following conditions:

1. The airplane flight manual normal or non-normal sections specify that engine inoperative

approach capability has been demonstrated and procedures are available.

2. The pilot and, if applicable, aircraft dispatcher have taken into account the landing runway length

needed for the inoperative engine configuration and corresponding approach speeds, and obstacle

clearance can be maintained in the event of a missed approach.

3. The pilot and, if applicable, aircraft dispatcher have determined that the approach can be

conducted within the wind, weather, configuration, or other relevant constraints demonstrated for the

configuration.

4. The pilot and, if applicable, aircraft dispatcher have determined from interpretation of the best

available information that the runway is expected to be free from standing water, snow, slush, ice, or other

contaminants.

5. The pilot is confident that the aircraft has not experienced damage related to the engine failure

that would make an engine inoperative Category III approach unsuccessful, or unsafe.

6. The operator is approved and the pilot is qualified to conduct a Category III engine inoperative

approach.
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7. The pilot and, if applicable, aircraft dispatcher consider that conducting a Category III approach

is a safe and appropriate course of action.

10.8.4. Engine Failure During Approach, Prior to Alert Height or Decision Height. If the

aircraft, operator, and crew meet paragraphs 5.17 for the aircraft and sections 10.8.2 or 10.8.3 for

operational use, a Category III approach may be continued if an engine failure is experienced after

passing the final approach fix.

In the event that an aircraft has not been demonstrated for engine inoperative Category III approach

capability, or the operator or crew have not been authorized for Category III engine inoperative

approaches, then, regardless of flight phase, continuation of an approach in the event of an engine failure

is permitted only in accordance with the emergency authority of the pilot to select the safest course of

action.

NOTE: For some aircraft configurations, it may be necessary to discontinue the

approach after passing the final approach fix or final approach point; re-trim the

aircraft for an inoperative engine, and then re-initiate the approach in order to be

able to appropriately complete a satisfactory Category III landing.

10.8.5. Engine Failure After Passing Alert Height or Decision Height. If an engine fails after

passing the Alert Height or Decision Height, the procedure specified in the airplane flight manual for

normal or non-normal operations should be followed. All Category III approvals must consider the case

of engine failure at, or after, DH or AH. Standard operations specifications are considered to address this

case. "Engine inoperative Category III capability" is not specifically a factor in determining response to

this situation.

10.9. New Category III Operators. New operators should follow demonstration period provisions

of section 10.5.2. Additionally, typical acceptable minima step down provisions approvable by FAA

are as follows:

Starting from Category I

Fail - Passive Landing System 100 ft. DH/RVR1000 then 50 ft. DH/RVR600

Fail - Operational Landing System 100 ft. DH/RVR1000 then RVR600, then RVR300

Starting from Category II

Fail - Passive Landing System 50 ft. DH/RVR600

Fail - Operational Landing System RVR600 then RVR300

Each runway/procedure not already being used by any operator of a similar type aircraft must be

successfully demonstrated by a line service or an evaluation landing using the Category III system and

procedures, in Category II or better conditions, for each aircraft/system type (e.g., B767, L1011). Once

this capability has been successfully demonstrated by any operator for a particular runway and aircraft
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type, subsequent operators may take credit for that demonstration and need not re-demonstrate suitable

performance. However, the operator must appropriately address special airports/runways as noted in

section 10.7 and the FAA Category II/Category III Status Checklist.

10.10. Credit for Experienced Category III Operators for New Authorizations. Experienced

operators are considered to be those operators having successfully completed their initial 6 month/ 100

Category III landing demonstration period, and have current operations specifications authorizing use of

lowest applicable or intended Category III minima. Sections 10.10.1 through 10.10.3 below address

examples of Category III program changes where "experienced operator" credit may apply.

Operators authorized for Category III using one class of system (e.g., autoland) but who are introducing a

significantly different class of system as the basis for a Category III authorization (e.g., manually flown

Category III approaches using a HUD) are typically considered to be "New Category III operators" for

the purposes of demonstration period provisions and acceptable minima "step down" provisions for that

class of system (see section 10.9).

10.10.1. New Airports/Runways. New airports/runways may be added to an experienced

Category III operators OpSpecs without further demonstration, if the same or equivalent

aircraft/airborne system for the approach are shown on the Category II/III status checklist.

Otherwise, the operator needs to accomplish a line service landing at Category II or better weather

conditions to ensure satisfactory performance. Special runways on the FAA Category II/Category III

Status Checklist (e.g., irregular terrain runways) may still require special evaluation.

Prior to approval of Category III minima for a particular aircraft type on any facility not formerly

approved for Category III use for that type of aircraft, acceptable flight guidance (e.g., autoland, or

autoland and rollout) performance if applicable, should be verified. This verification may be made by

airline and/or FAA observation of automatic landings during line operations or training flights in weather

conditions at or above Category II minima to determine adequacy of the facility for that type aircraft. In

certain special cases, as designated by the FAA, where the characteristics of the pre-threshold terrain

may induce abnormal performance in certain automatic flight control systems, additional analysis or flight

demonstrations in line service may be required for each aircraft type prior to approval of Category III

minima.

10.10.2. New or Upgraded Airborne System Capability. Unless otherwise specified by

AFS-400, experienced Category III operators may initially use new or upgraded airborne system

capabilities/components to the lowest authorized minima established for those systems or components,

consistent with the examples provided below. Operators may also request reduced length

demonstration periods, consistent with the new airborne systems to be used, FAA FSB requirements,

and NAVAIDs, runways, and procedures to be used. Examples of this provision include addition of a

new capability such as "engine inoperative" autoland to a system currently approved for "all engine"

Category III, or introduction of an updated flight guidance system software version on an aircraft
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previously authorized for Category III for that operator. In such cases, the lowest authorized minima

may be used, or may continue to be used, without additional demonstration.

10.10.3. Adding a New Category III Aircraft Type. Experienced Category III operators may

operate new or upgraded aircraft types/systems, or derivative types, using reduced length demonstration

periods (e.g., less than 6 months/100 landings) when authorized by AFS-400. Demonstration

requirements are established considering any applicable FAA FSB criteria, applicability of previous

operator service experience, experience with that aircraft type by other operators, experience of

flightcrews of that operator for Category III and the type of system, and other such factors, on an

individual basis. Appropriate minima reduction steps may also be established for an abbreviated

demonstration period, consistent with prior operator experience, NAVAID’s and runways used, and

procedures to be used, etc. (e.g., newly acquired B757s being added to Category III OpSpecs, in

addition to an operator's currently approved Category III A300 and MD-80 fleets).

10.11. Category III Program Status Following Operator Acquisitions/Mergers. Category III

operators involved in acquisitions of other operators, or mergers, and their respective CHDO’s, must

ensure compatibility of programs. Procedures, airborne systems, runways served and any other relevant

issues must be addressed before amending operations-specifications, or advising the surviving or

controlling operator of the status of Category III OpSpecs of the acquired or merged operator. If CHDO

doubt exists regarding applicability or status of Category III OpSpecs provisions for a resulting new,

surviving, acquired, or merged carrier, AFS-400 should be consulted.

10.12. Initiating New Combined Category II and Category III Programs. Unless otherwise

specified by AFS-400, Category II and Category III programs may be initiated simultaneously for new

operators, or for existing operators currently approved for Category I. Appropriate provisions of both

AC 120-29, as amended, and AC 120-28D are used. Operational Suitability Demonstration programs

may be simultaneously conducted as long as procedures and systems applicable to both Category II and

Category III minima are assessed (e.g., use of Category II DH vs. Category III AH). The lowest

authorized minima established during the evaluation program should be as specified in section 10.9.

10.13. United States Carrier Category III Operations at Foreign Airports. An applicant having

U.S. Category III approval may be authorized to use Category III minima at foreign airports on the FAAapproved list. Airports are approved and listed when the following conditions are met:

1. The airport is approved for Category III operations by the appropriate foreign airport authority.

2. The visual aids are equivalent to those used for U.S. Category III approaches.

3. Electronic ground aids are at least equivalent to those designated for U.S. Category III approaches.

4. The FAA office having responsibility for the area in which the foreign facility is located has

reviewed and verified the conditions in items (1), (2), and (3) above.
AC 120-28D 07/13/99

Page 82

The major factors to be considered when approving such airports will be the equivalence with U.S.

standards of the approach light systems, high intensity runway lights, in-runway lights, quality and integrity

of the approach and landing guidance systems, runway marking, procedures for reporting runway

visibility, and airport surface traffic control. Although it is recognized that the systems at foreign airports

may not be exactly in accordance with U.S. standards, it is important that any foreign facilities used for

Category III provide the necessary information or functions consistent with the intent of the U.S.

standards. Carriers desiring Category III approvals at foreign airports or runways not on the FAAapproved list should submit such requests through its FAA principal operations inspector to AFS-400,

FAA Headquarters, Washington, D.C.

Typically for airports at which JAA rules apply, U.S. operators may expect to receive authorization to use

the most restrictive of either the minima in their U.S. authorization for the aircraft type or flightcrew, or the

lowest applicable JAA minima for the airport and runway used.

U.S. operators and pilots of aircraft operating internationally should be familiar with any unique

provisions applicable to Category III operations at particular airports outside the U.S. As an example,

international operators and pilots should be familiar with the need to convert minima specified in one

form (e.g., meteorological visibility) to another different but equivalent form (e.g., RVR – see Section

8.6.2.2 and Appendix 7, Standard Operations-Specifications Part C Paragraph C051 for the

applicable conversion table).

Figure 10.13-1 provides a checklist for carriers use to facilitate approval of Category II/III operations

at facilities listed in the controlling states Aeronautical Information Publication (AIP). It should be used

to ensure suitability of the intended facility and to verify conformance or equivalence with U.S. standards

at non-U.S. airports. Completion of this checklist must reflect achieved or completed status, not

planned actions for the future. For ICAO states that do not maintain an AIP, a copy of the Notice to

Airmen (NOTAM), obstruction data, and/or a reliable and regular method of correspondence with the

charting services used by U.S. certificate holders must be attached.
07/13/99 AC 120-28D

Page 83

FACILITY CHECKLIST FOR CATEGORY II/III

(FOR NON-U.S. FACILITIES)

AIRPORT (ICAO ID): ________ COUNTRY: ____________ DATE: ____________

Runway: ________ Length: _________ Width: _________ G/S Angle (deg.): ___________

Lowest Minima ________________________ (ft./m) Runway TCH _____________ (ft./m)

Special Limitations (if any):

LIGHTING:

Approach _____ TDZ _____ Centerline ____ HIRL ____ Stopbars _____

Other (e.g., PAPI):

MARKINGS:

Runway _______ Taxiway _______ Other (e.g., Taxiway Position) __________

Critical Area Protection Policy (ceiling/visibility or conditions):

LOC ____________________________ G/S ________________________________

METEOROLOGICAL DATA: METAR’s ________ TAF’s ___________

TRANSMISSOMETERS:

(Locations/Lowest RVR reported/readout step increment)

Touchdown _______________ Mid _________________ Rollout _______________

OBSTRUCTION CLEARANCE ASSESSMENT COMPLETION DATE: _________________

Verified by: certificate holder ________, “state of the aerodrome” __________, other _______

Irregular terrain a factor (Y/N): _______ Similar type aircraft currently operate (Y/N) ________

NOTAM SOURCE/CONTACT: ___________________________________________________

FIELD CONDITIONS SOURCE/CONTACT ________________________________________

Attached procedure has been developed in accordance with:

FAA Handbook 8260.3B (TERPS) ____ ICAO PANS-OPS Doc. 8168-OPS/611, Vol.-11 ____

Other Criteria Accepted by FAA ____ (indicate criteria) ______________________________

Facility reviewed in accordance with ICAO Manual of All Weather Operations, as revised

(DOC 9365/AN910) chapters 3, 5, and 6 DATE REVIEW COMPLETED: _________________

Name: ____________________________

Title: _____________________________

Signature: _________________________

Date: _____________________________

Attachments List:
AC 120-28D 07/13/99

Page 84

Figure 10.13 - 1

10.14. Category III Operations on Off-Route Charters. Unless otherwise specified by AFS-400,

experienced Category III operators may receive authorization to use Category III minima at United States

off-route charter airports and runways as follows:

1) The runway must be on the FAA Category II/Category III status checklist, and not be restricted

or require special evaluation (e.g., irregular terrain).

2) The aircraft used must be the same as or equivalent to an aircraft type already using the facility

by another FAA certificated operator (e.g., a charter flight could be considered acceptable using an

MD-83 with a "-971 Flight Guidance Control System (FGCS)" at a runway which had current

Category III operations authorized for an MD-81 of another operator, but with an earlier but similar

FGCS version).

3) Pilots must have sufficient information to safely conduct the low visibility operation regarding

familiarity with the airport (e.g., SMGC procedures, taxi hold point or gate direction markings, gate

location to be used).

4) The OpSpecs must authorize off-route charter Category III procedures, and

5) The CHDO must be advised of the specific airports, aircraft, crew qualifications and any special

provisions to be used.

10.15. Approval of Category III Minima and Issuance of Operations Specifications.

Applicants should submit documentation requesting approval of Category III weather minima to the

FAA Certificate Holding District Office (CHDO) or Flight Standards District Office (FSDO)

responsible for that operator's certificate. The application should demonstrate compliance with the

appropriate provisions of applicable sections of this AC, particularly sections 7 through 12. Proposed

operations specifications provisions should be included with the application.

The operators application documentation should be evaluated by the CHDO/FSDO and forwarded, with

any recommendations, to the Technical Programs Division, AFS-400, FAA Headquarters, Washington,

D.C., for review and concurrence. This review and concurrence is necessary prior to CHDO approval of

Category III minima.

Following AFS-400 concurrence, OpSpecs authorizing Category IIIa or Category IIIb minima may be

issued (see Appendix 7 for sample Operations Specifications examples).

During the period following the issuance of new or revised operations specifications for Category III

(typically 6 months), the operator must successfully complete a suitable operations demonstration and

data collection program in "line service" for each type aircraft, as the final part of the approval process.
07/13/99 AC 120-28D

Page 85

The approval process is considered to be completed following a successful demonstration period. This

is to ensure appropriate performance and reliability of the Category III system with that operators

aircraft, procedures, maintenance, airports, and NAVAID’s. This process must be completed before

operations down to lowest requested minima are authorized. Section 10.5 addresses appropriate

demonstration process criteria.

In situations involving newly manufactured airplanes or where otherwise authorized by FAA, the

operations demonstration and data collection process may be initiated prior to the issuance of Category

III operations specifications. Sections 10.9 through 10.12 provide criteria that may be used to establish

acceptable operations demonstration time periods, and demonstration program scope for different

operator situations, aircraft variants, and low visibility operating experience history.

10.16. Operations Specification Amendments. The operator is responsible for maintaining current

OpSpecs reflecting current approvals authorized by FAA. Once FAA has authorized a change for

airborne systems, new runways, or other authorizations, appropriate and timely amendments to affected

OpSpecs should be issued. Issuance of amendments to guidance or procedures in other related

material such as the Flight Operations Manual or Training Program may also be required. When

updated standard operations specification provisions are adopted by FAA, provisions of those updated

operations specifications should normally be applied to each operator's program in a timely manner.

10.17. Use of Special Obstacle Clearance Criteria (e.g., RNP criteria). This paragraph addresses

use of special criteria such as "Required Navigation Performance" (RNP) criteria. Pending

implementation of RNP criteria for public use Standard Instrument Approach Procedures (SIAP’s),

obstacle assessments using RNP criteria will be conducted on a case-by-case basis, and for Category III,

only authorized as an element of special procedures for RNP qualified operators, using RNP qualified

aircraft. Early application of RNP for special procedures is typically intended to apply to instrument

procedure segments classified as a transition to a final approach segment, or to facilitate definition of

suitable missed approach segments. Use of special obstacle clearance criteria or RNP criteria must be

approved by AFS-400 for any Category III procedures.

If RNP procedures are used, the operator must have an acceptable method to assure that any

waypoints which are considered critical to an instrument procedure (if any) are correctly defined, and

are loaded into each applicable aircraft’s database, initially, and at each change cycle.

10.18. Proof-of-Concept Demonstration for New Systems/Methods. Proof-of-Concept [PoC]

as used in this AC is defined as:

A generic demonstration in a full operational environment of facilities, weather, crew complement,

airborne systems and any other relevant parameters is necessary to show concept validity in terms of

performance, system reliability, repeatability, and typical pilot response to failures as well as to

demonstrate that an equivalent level of safety is provided.
AC 120-28D 07/13/99

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Proof-of-Concept may be established by a combination of analysis, simulation and/or flight

demonstrations in an operational environment. PoC is typically a combined effort of FAA airworthiness

and operational organizations with the applicant, with input from any associated or interested

organizations.

A typical PoC program consists of the following elements:

1. Applicant submits a request to either FAA Aircraft Certification or Flight Standards.

2. Meetings are arranged to include all disciplines involved: Aircraft certification; Flight Standards;

National Resource Specialists (NRS’s); the applicant, and supporting personnel as necessary (e.g., Air

Traffic and representative flightcrews, as appropriate).

3. A test plan is established which includes input from applicable FAA organizations, the applicant,

and as applicable, industry user groups.

4. The test plan should include as a minimum: system definition, operations procedures, qualification,

training, weather and environment definition, normal, rare-normal, and non-normal conditions to be

assessed, flightcrew, test subject, and test crew requirements, test procedures, test safety constraints as

applicable, assessment criteria, and analysis, simulator and test aircraft requirements, and a clear

understanding of what constitutes a successful test and proof of concept.

5. PoC is conducted using agreed subject pilots, as appropriate.

6. PoC data is collected in a suitable simulator environment and validated in a realistic airplane

environment.

7. FAA is responsible for assessing the PoC data which is typically provided to FAA as agreed by

FAA and the applicant. FAA reports relevant findings to the applicant and if applicable, interested

industry representatives.

8. FAA operations and airworthiness organizations use the data to develop criteria for approval of

type designs, certification processes and procedures, operating concepts, facilities, flightcrew/aircraft

dispatcher and maintenance qualification, operations specification, operations procedures, manuals,

AFM’s, maintenance procedures, and any criteria necessary.

9. FAA AC criteria for airworthiness and operational approval typically is a product of PoC

assessment.

This process is presented pictorially in the following figure.
07/13/99 AC 120-28D

Page 87

TECHNOLOGY DEVELOPMENT PROCESS

LETTER AND

APPLICATION

TO ACO

APPLICANT

ACO INITIATES

PROJECT

ACO

LETTER OF

INTENT TO

FAA-AFS

OPERATOR

DEVELOP

TECHNOLOGY

TEAM

ACO, AFS

DETERMINE

APPLICATIONS

AND CONSTRAINTS

IN THE NATIONAL

OPERATIONAL SYSTEM

AFS HQ

Note 2)

DEVELOP PROOF OF

CONCEPT (POC)

TEST REQUIREMENTS

AND SUCCESS CRITERIA

ACO, AFS

CONDUCT POC

ACO, AFS

REPORT TEST

RESULTS

ACO, AFS

DEVELOP TYPE

DESIGN REQUIREMENTS

- Certification

- Operation

- Maintenance

ACO, TSS, AFS

DEVELOP USER

REQUIREMENTS

- Operation

- Maintenance

- Training

Wash AFS, POI's

Handbook

DESIGN

INDUSTRY Note 1)

ACO TYPE DESIGN

CERTIFICATION

ACO

ACO

AIRPLANE

FLIGHT MANUAL

DRAFT ADVISORY

CIRCULAR (AC)

ACO, TSS, AFS

POI AFS

OPS APPROVAL

OPS SPECIFICATIONS

FCOM-FLIGHT CREW

OPERATING MANUAL

Note: 1) Futher modifications to the applicant's original Type Design may require additional

technology revisions and/or follow on Proof of Concept testing.

2) The AFS group has the responsibility to coordinate with all Industry technology

groups (ALPA, APA, ATA, ADF Industry, manufactures, vendors, DOD, NASA, etc.)

3) Both the FAA ACO and FAA AFS should be contacted to provide certification and

operational data to the respective offices.

Index:ACO - Aircraft Certification Office (Including Aircraft Evaluation Group)

AFS - Washington Flight Standards Policy Office

TSS - Transport Standards Staff RRD7/19/94

Note 3)
AC 120-28D 07/13/99

Page 88

11. FOREIGN AIR CARRIER CATEGORY III AT UNITED STATES AIRPORTS (PART

129 OPERATIONS SPECIFICATIONS).

11.1. Use of ICAO or FAA Criteria. International operators requesting or authorized for

Category III at U.S. airports should meet criteria of 11.1.1 through 11.1.3 below.

11.1.1. Acceptable Criteria. Criteria Acceptable for use for assessment of international operator's

applications for Category III at U.S. airports includes this AC, equivalent JAA criteria, or the ICAO

Manual of All Weather Operations DOC 9365/AN910, as amended.

International operators previously approved by FAA in accordance with earlier criteria may continue to

apply that earlier criteria. International operators seeking credit for operations addressed only by this

revision of AC 120-28D (e.g., Category III HUD operations) must meet criteria of this AC, or

equivalent criteria acceptable to FAA, for those applicable provisions.

11.1.2. Foreign Operator AFM Provisions. Unless otherwise authorized by FAA, aircraft used by

international operators for Category III within the U.S. should have AFM provisions reflecting an

appropriate level of Category III capability as demonstrated to or authorized by FAA, or demonstrated to

or authorized by an authority recognized by FAA, as having acceptable equivalent Category III

airworthiness criteria (e.g., European JAA, Canada MOT, UK CAA).

11.1.3. Foreign Operator Category III Demonstrations. International (Foreign) Air Carriers

meeting FAA criteria, or criteria acceptable to FAA (e.g., European JAA, ICAO Criteria including

Doc 9365/AN910), and having more than 6 months experience in use of Category III operations with the

applicable aircraft type may be approved for Category III in accordance with provisions of their own

regulatory authority, or in accordance with standard provisions of 14 CFR part 129 OpSpecs, which ever

is the more restrictive. A separate demonstration period is not required for FAA if the “State of the

Operator” does not require it. However, operators approved in accordance with this provision may

nonetheless be subject to additional FAA demonstration for special situations, such as at airports with

irregular underlying terrain (see 11.3), or for aircraft types not having flown to U.S. facilities having

Category III procedures.

For international (foreign) operators having current U.S. Category III authorization, the Category III

demonstration period may be reduced or waived for addition of a new type aircraft to the existing

Category III authority. The demonstration period may be reduced or waived to the extent that a

successful demonstration has been accepted by FAA for that aircraft type for any other U.S. or

international operator.

International (Foreign) Air Carriers not meeting above provisions may be subject to the demonstration

described at 10.5.2 and 10.9 (equivalent to those necessary for U.S. operators) as determined

applicable by FAA.
07/13/99 AC 120-28D

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11.2. Issuance of Part 129 Operations Specifications. International (Foreign) Air Carriers

operating to U.S. airports which meet applicable provisions above are approved for Category III

through issuance of part 129 OpSpecs (see Appendix 7).

Operators intending Category III operations at U.S. designated irregular terrain airports, or airports

otherwise requiring special assessments must successfully complete those assessments prior to use of

those facilities.

11.3. Use of Certain United States Facilities. Foreign operators typically use Category III

procedures in the U.S. which are available as unrestricted public use procedures. However, FAA may

also authorize certain restricted public use procedures and special Category III approach procedures for

non-U.S. Operators. Typically, these procedures require special airborne equipment capability, special

training, or non-standard facility and obstacle assessments. These special procedures are identified on the

Category II/III status checklist and are not usually published as a part 97 Category III SIAP.

Foreign operators may be eligible to use certain of these procedures if they meet the same special criteria

as would apply to a U.S. operator, and if they are approved by their own authority specifically for the use

of the procedure. Some procedures may not be eligible for foreign use because of other applicable

restrictions such as a restriction placed on private facility use. Special or restricted procedures require

both FAA authorization and specific authorization from the state of the operator's controlling authority for

each procedure. This is to ensure that both the operator and foreign authority are aware of the special

provisions needed, and to ensure equivalent safety to use of standard ICAO criteria.

Each foreign operator seeking Category III procedure authorization at a facility not published as a standard

and unrestricted Category III SIAP, or at any other facilities identified as special or restricted on the FAA

Category II/III Status checklist, and that operator's controlling authority must:

1. Be aware of the restrictions applicable to the procedure (e.g., facility status),

2. Provide evidence to FAA of the controlling authority's approval of the operator for each special

procedure requested, and

3. Must have the applicable limitations and conditions included in that operator's part 129 OpSpecs

for each procedure to be used.

Foreign operators shall not normally be authorized special Category III operations to minima lower than

those specified in part 97 Category III SIAPS consistent with ICAO criteria.

12. OPERATOR REPORTING, AND TAKING CORRECTIVE ACTIONS.

12.1. Operator Reporting. The reporting of satisfactory and unsatisfactory Category III aircraft

performance is a useful tool in establishing and maintaining effective maintenance and operating policy
AC 120-28D 07/13/99

Page 90

and procedures. Information obtained from reporting data and its analysis is useful in recommending

and issuing appropriate corrective action(s).

Accordingly, for a period of at least 1 year after an applicant has been advised that its aircraft and

program meet Category III criteria, and reduced minima are authorized, the operator is to provide a

monthly summary to the FAA of the following information:

1. The total number of approaches where the equipment constituting the airborne portion of the

Category III system was utilized to make satisfactory (actual or simulated) approaches to the applicable

Category III minima (by aircraft type).

2. The total number of unsatisfactory approaches by airport and aircraft registration number with

explanations in the following categories - airborne equipment faults, ground facility difficulties, aborts of

approaches because of ATC instructions, or other reasons.

3. Notify the certificate-holding office as soon as possible of any system failures or abnormalities

which require flightcrew intervention after passing 100 ft. during operations in weather conditions below

Category I minima.

4. Upon request, the certificate-holding district office will make this information available to AFS400 for overall Category III program management, or to assist in assessment of program or facility

effectiveness.

This 1 year recording and reporting requirement applies to the initial Category III airplane, however,

when maintained over longer periods of time the report data substantiates a successful program and can

identify trends, or recurring problems that may not be related to aircraft performance.

NOTE: The reporting burden contained in this AC does not require Office of

Management and Budget approval under the provisions of the Paperwork

Reduction Act of 1980, according to section 3502(4)(a).

12.2. Operator Corrective Actions. In addition to the corrective actions contained in the operations

and maintenance manuals, operators are expected to take appropriate corrective actions when they

determine that conditions exist which could adversely affect safe Category III operations. Examples of

situations for which an operator may need to take action restricting, limiting, or discontinuing Category III

operations include:

Repeated aircraft system difficulties, repeated maintenance write-ups, chronic pilot reports of

unacceptable landing performance, applicable service bulletin issuance, AD’s, NAVAID status or

performance problems, applicable NOTAM’s, airport facility status change, air traffic procedure

adjustment, lighting, marking, or standby power system status outages, airport construction, obstacle

construction, temporary obstacles, natural disasters, adverse weather, snow banks, snow removal, icy

runways or taxiways, deep snow in glide slope critical areas, inability to confirm appropriate critical area

protection at non-United States airports, and other such conditions.
07/13/99 AC 120-28D

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Examples of appropriate corrective action could be an adjustment of Category III programs,

procedures, training, modification to aircraft, restriction of minima, limitations on winds, restriction of

NAVAID facility use, adjustment of payload, service bulletin incorporation, or other such measures

necessary to ensure safe operation.