NASA/TM—2006–214531 

 

Human Factors Considerations for 

Performance-Based Navigation 

 

Richard Barhydt and Catherine A. Adams 

Langley Research Center, Hampton, Virginia

 

December 2006
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NASA/TM—2006–214531 

 

Human Factors Considerations for 

Performance-Based Navigation 

 

Richard Barhydt and Catherine A. Adams 

Langley Research Center, Hampton, Virginia 

 

National Aeronautics and 

Space Administration 

Langley Research Center 

Hampton, VA 23681 

December 2006
Acknowledgments 

The authors would like to thank our FAA sponsors Kathy Abbott, Terry Stubblefield, and 

Tom McCloy for their technical insight and support for this project. We also thank the technical 

experts who have donated their time and provided substantial contributions. Special recognition 

is due to John Anderson (Continental Airlines), Sam Miller (Boeing), Tom Petrakis (FAA, Las 

Vegas TRACON), Phil Mullis (Southwest Airlines), Hal Andersen and Tom Leard (Naverus), 

Brian Townsend (Air Line Pilots Association), Nikki Haase (Human Solutions, Inc.), Don Porter 

(FAA), Ken Speir (Delta Airlines), Frank Alexander (Northwest Airlines), Brian Will (American 

Airlines), Tom Imrich (Boeing), and Bruce Tarbert (FAA). 

Available from: 

NASA Center for AeroSpace Information 

7115 Standard Drive 

Hanover, MD 21076-1320 

(301) 621-0390 
Table of Contents 

EXECUTIVE SUMMARY 3

INTRODUCTION 5

MOTIVATION 5

DEVELOPMENT OF ISSUES LIST AND INTENDED PURPOSE 6

ISSUES LIST FINDINGS 8

ATC PROCEDURES 8

FLIGHT CREW PROCEDURES 9

AIRLINE PROCEDURES 10

Pre-Departure Clearance (PDC) 10

Training 10

EQUIPMENT CAPABILITIES 10

FMS (Other than Navigation Database) 10

Electronic Flight Instrumentation Systems (EFIS) 12

Alerting 12

Non-Satellite Position Sources 12

Electronic Flight Bag (EFB) 13

FMS NAVIGATION DATABASE 13

PROCEDURE DESIGN 14

RNAV SID/STAR 15

RNAV Approaches 16

RNP Approaches 17

RNP Parallel Approach Transition (RPAT) 17

En Route Procedures 18

CHARTING 18

CHART/DATABASE COMMONALITY 19

APPROACH NAMING AND APPROACH CLASSIFICATION 20

FLIGHT PLAN SUFFIXES 21

NOTAMS 22

ISSUES LIST PRIORITIZATION 22

PRIORITIZATION CRITERIA 22

RECOMMENDATIONS FOR EARLIEST CONSIDERATION 23

Human Factors Guidelines for RNAV/RNP Instrument Procedure Design 23

Identification of Lessons Learned during RNP SAAAR Experience and Recommendations for Implementation of 

Public RNP Procedures 23

Continuation of and Coordination among Working Groups that Identify and Propose Solutions for Operational 

Problems Associated with RNAV SID/STAR Procedures 24

Consideration of Potential Changes to Approach Naming, Approach Classification, and Flight Plan Suffixes 24

Resolution of High Priority Items Concerning Chart/Database Commonality 24

Review of Aircraft Equipment-Related Impact of RNAV and RNP Operational Events 24

Review of Issues Pertaining to Use of Baro VNAV during Instrument Approaches 24

SELECTION OF TARGETED STUDIES 25

CONCLUSIONS 25

REFERENCES 26

APPENDIX A: HUMAN FACTORS ISSUES LIST 28
2

THIS PAGE INTENTIONALLY LEFT BLANK 
3

Executive Summary 

 A transition toward a performance-based navigation system is currently underway in both the 

United States and around the world. Performance-based navigation incorporates the use of Area 

Navigation (RNAV) equipment that is not reliant on the location of ground-based navigation aids. In 

addition to the point-to-point capabilities offered by RNAV, new procedures are also being implemented 

that incorporate Required Navigation Performance (RNP). Aircraft certified for RNP operations are able to 

meet specific requirements for position determination and track conformance. RNAV and RNP procedures 

offer significant benefits to both operators and air traffic managers. These benefits include better access to 

terrain-limited airports, more environmentally friendly flight paths, and significant gains in airspace 

efficiency. Performance-based operations are being implemented in both the terminal area and en route 

environments. 

 The implementation of these procedures has produced tangible benefits at a number of different 

airports. According to the FAA Roadmap for Performance-Based Navigation, new RNAV procedures in 

the terminal area have reduced air-ground communications and led to reductions in flight times and 

distances.2

 These positive outcomes notwithstanding, the transition to RNAV and RNP, has caused some 

human performance issues to emerge that have prevented the full realization of benefits from the new 

procedures. As new performance-based applications are considered, other human performance issues are 

also anticipated. To provide a more seamless transition to RNAV and RNP, a National Aeronautics and 

Space Administration (NASA) and Federal Aviation Administration (FAA) project has been initiated to 

identify a broad set of human factors issues associated with performance-based navigation and to make 

recommendations for prioritizing work on those issues. 

 The primary objective of the project is to provide greater awareness of human-performance issues 

related to RNAV and RNP to a wide range of stakeholders. Products from this project are expected to 

benefit air navigation service providers, regulators, manufacturers, and training professionals. With this 

awareness, it is expected that instrument procedures, training programs, regulatory reviews, and operational 

procedures will place additional emphasis on human factors. 

To address these goals, the project has developed and prioritized a list of human factors issues 

related to performance-based navigation. The list concentrates on air carrier operations. It was created 

based on a literature review, attendance at government/industry committee meetings, and discussions with 

technical experts. Major results from a separate review of Aviation Safety Reporting System (ASRS) data 

related to RNAV Standard Instrument Departures (SIDs) and Standard Terminal Arrival Routes (STARs) 

have also been incorporated.6

 Where possible, the list has been supplemented with summary information 

on known efforts to address these issues. Categories considered include operational procedures, aircraft 

equipment capabilities, procedure design, charting, and the application of current approach categories and 

flight plan suffixes in a performance-based environment. While these issues are grouped and discussed 

separately, many of them are interdependent or have multiple implications. They may also combine and 

cause a cumulative effect on operations. 

 Air traffic control procedures have been affected by the transition to performance-based navigation. 

Some conventional terminology is less able to accommodate the greater prevalence of route-based 

clearances associated with RNAV procedures. Although often necessary for air traffic management 

purposes, late runway changes assigned by controllers can increase pilot workload due to necessary 

programming changes within the Flight Management System (FMS). Pilots also require greater awareness 

of this procedure management issue and are encouraged to take extra care to ensure that the correct runway 

is loaded into the FMS after a change has occurred. 

 RNAV and RNP procedures have increased the importance of some tasks performed by pilots and 

have also introduced some new ones. Pilots must allow adequate time to properly load and brief their SID, 

STAR, and approach charts. While containing many elements common with existing procedures, these 

procedures can be more detailed than their conventional counterparts. Considering the increased reliance 

on the FMS for RNAV and RNP procedures, airlines may benefit from reviewing their training programs 

and ensuring that they meet pilot workload and situation awareness demands. 
4

 RNAV and RNP procedures require tight adherence to the published path and are often more 

sensitive to variance in path construction and guidance techniques amongst flight management systems. 

Differences such as path construction at waypoints, handling of speed constraints, and mode transitions can 

cause path inconsistencies. In some cases, these differences have resulted in traffic conflicts. In addition to 

the FMS, design considerations related to other supporting systems were also noted. 

 The FMS navigation database plays a key role in the implementation of performance-based 

procedures. Several technical experts have recommended more thorough database integrity checking at all 

data processing levels, from origination by source countries to procedure coding in a particular FMS unit. 

 Over-complexity has been cited as a common concern for several different types of terminal area 

procedures. Several aspects may contribute to complexity including the number of waypoints required for 

RNAV procedures, chart clutter, successive altitude constraints in close proximity, and conditional 

constraints. Commonality with other procedures has also led to misidentification by pilots. A set of 

guidelines that assesses the operational effects of procedure design attributes (both individually and in 

combination) could be valuable for enabling the design of new procedures that achieve benefits while 

maximizing human performance. 

 RNP approaches now provide the capability to incorporate highly precise turn segments. This 

significant enhancement is causing airline personnel to re-think traditional definitions of “stabilized” 

approaches. The appropriate minimum altitude for turn segments and the use of turn segments at decision 

altitude are also major issues requiring further consideration. 

 Many have cited the current approach naming and approach classification system as inadequate to 

support performance-based navigation. This system includes approach naming conventions based on 

aircraft equipment and the distinction between “precision” and “non-precision” approaches. A new 

classification system could improve clarity, but would need to consider the broad impact of the current 

system. 

Single letter flight plan suffixes used to delineate various equipment capabilities to controllers have 

also been called into question. In a performance-based environment, these codes may be insufficient for 

controllers to determine whether an aircraft is capable of performing a particular procedure. 

 Issues were prioritized based on recommended criteria from the Performance-based Aviation 

Rulemaking Committee (PARC) Human Factors Working Group, their potential impact on performancebased navigation, their prevalence in discussion at committee meetings, and the importance assigned to 

them by technical experts. Major issues that are recommended for near-term focused consideration include 

the 

• development of human factors guidelines for instrument procedures, 

• application of lessons learned from prior experience with specially-tailored RNP approaches toward 

implementation of public RNP approaches, 

• continuation of efforts to resolve operational issues associated with RNAV SID and STAR 

procedures, 

• review of approach naming and approach classification systems, flight plan suffixes, and assessment 

of proposed new systems designed to better accommodate performance-based operations, 

• resolution of major issues related to chart/database commonality, 

• review of aircraft equipment-related impact of RNAV and RNP operational events, 

• and a review of several specific issues related to the use of barometric vertical navigation (“Baro 

VNAV”). 

Decisions to consider targeted investigation of a particular issue should consider priorities, available 

resources, and the ongoing work of other organizations. Strong collaboration between different groups 

addressing these issues will enable more efficient use of resources and a greater likelihood that compatible 

solutions will be realized. 
5

Introduction 

Motivation 

In the U.S. National Airspace System and elsewhere in the world, a move is underway to transform 

navigation services from those emphasizing the use of specific sensors to those that focus on a performance 

capability. As part of this trend, more and more aircraft are being flown using area navigation (RNAV), a 

technology that allows point-to-point travel without regard to the location of ground-based radio stations. 

An extension of RNAV capability, known as Required Navigation Performance (RNP), specifies various 

levels of performance capabilities. Aircraft certified to a particular RNP have a demonstrated ability to 

remain within a containment area defined by their capability level.1

 

 RNAV and RNP are seen as key enabling factors in improving the efficiency and capacity of the 

National Airspace System (NAS).2

 New procedures that rely on RNAV capabilities provide pilotnavigated routes that conform to local air traffic flow management needs and meet terrain and airspace 

challenges. Lower path tracking variability associated with these procedures improves consistency and 

allows controllers to use available airspace more efficiently. Controllers are able to issue more routeoriented clearances and rely less on radar vectoring in the terminal area. This change has reduced airground communications and led to more organized and predictable traffic flows. Because RNAV routes 

are no longer constrained by the location of ground-based navigation aids, procedures can also be 

developed that improve access while avoiding unusable airspace. RNAV provides additional options for 

procedure designers to accommodate challenging constraints such as terrain, noise-sensitive areas, and 

special use airspace.3

 These benefits relate directly to the performance-based services and trajectory-based 

operations capabilities envisioned for the Next Generation Air Transportation System (NGATS).4

 The 

Joint Planning and Development Office (JPDO), a consortium of government agencies and industry 

representatives, has been chartered to implement the NGATS by 2025. 

RNAV and RNP are already yielding significant benefits. At the same time, these capabilities have 

led to some fundamental changes in aircraft operations, flight crew and controller procedures, and in 

supporting aircraft and ground-based automation systems. As expected with any transition, some human 

performance issues have emerged during operations. 

Issues have been identified in several areas, including air traffic control (ATC) communication, the 

ability to perform RNAV procedures with various legacy systems, procedure design and charting, and the 

use of existing procedure classification systems employed by the Federal Aviation Administration (FAA). 

Many of these issues are not unique to RNAV and RNP operations. The new emphasis on 

trajectory-based operations has highlighted vulnerabilities that existed with legacy procedures and 

equipment but were not frequently exercised. In many cases, the new procedures have increased 

opportunities to use existing equipment and communication conventions. Pilots and controllers are also 

adapting to a more precise system that requires even greater attention to good operating procedures. 

 Human performance issues are being discussed in various forums. A number of 

government/industry committees such as the RNAV Task Force, the Performance-Based Aviation 

Rulemaking Committee (PARC), and several International Civil Aviation Organization (ICAO) panels 

regularly discuss these issues and potential mitigation strategies. Web-based information sites such as 

Bluecoat allow airline pilots to discuss issues they’ve encountered with others in the community. Issues are 

also raised through the Aviation Safety Reporting System (ASRS), a searchable database sponsored by the 

FAA and administered by the National Aeronautics and Space Administration (NASA). FAA documents 

are being developed to address them. With discussions taking place in multiple venues and across a 

number of organizations, there appears to be a strong need to organize the issues raised, discuss their 

relative importance, and make the information available to a wider audience. 

 
6

Development of Issues List and Intended Purpose 

In response to these needs, the NASA Langley Research Center, under joint sponsorship from the 

FAA, has undertaken a project to assemble and prioritize a list of human factors issues related to 

performance-based navigation. These issues focus on air carrier operations. The purpose of the Issues List 

and supporting analysis is to improve awareness of human factors for NAS stakeholders who conduct 

RNAV and RNP operations or offer related products and services. It also serves to provide guidance for 

government/industry committees that address RNAV and RNP issues. The document could be used 

effectively in a number of different ways. Air navigation service providers and manufacturers could take 

the issues raised into account when designing instrument procedures and aircraft systems, respectively. 

FAA personnel may develop or revise advisory circular material and certification guidelines for aircraft and 

flight crews involved in RNAV and RNP operations. Committees and research organizations could also 

consider the prioritized list when allocating resources to study relevant issues. The document may be 

helpful for training professionals who develop RNAV and RNP-related course material. 

This document focuses primarily on human performance issues that have occurred during 

implementation of RNAV and RNP. It is not intended to be a harsh critique of these operations, nor to 

imply that the procedures are unsafe or inherently difficult. Comparable or potentially more significant 

issues could exist with legacy procedures and are not addressed specifically in this document. A strong 

consensus exists in the aviation community that RNAV and RNP provide major safety, air traffic 

efficiency, and economic advantages over legacy systems and procedures. The reader is encouraged to 

consider the issues presented in light of these significant benefits. Coordinated actions taken to address 

these issues will likely lead to even greater operational performance. 

The Issues List has been developed through a wide literature review, attendance at 

government/industry committee meetings, and discussions with technical experts. As part of this effort, the 

authors conducted a more detailed review of the ASRS database for events occurring during the operation 

of RNAV Standard Instrument Departures (SIDs) and Standard Terminal Arrival Routes (STARs). While 

the details of the ASRS review have been discussed in a separate report,6

 the high level findings have been 

incorporated into the Issues List. 

Appendix A presents the list of issues compiled during this study. The first several columns 

identify the source of the issue. Many of the issues were captured from presentations given at committee 

meetings. Others were uncovered during a literature search of FAA publications such as Issue Papers, 

Advisory Circulars, Orders, and bulletins; a review of airline information websites such as Bluecoat, an 

assessment of pilot deviation reports and ASRS records, and through technical discussions with expert 

users. Where available, the expert identifying the issue and his or her organization are provided. 

A category is assigned for each issue. While many issues have ties to several different functional 

areas, category assignment is based on the aspect deemed to be most directly related to the issue cause. 

List categories were organized to capture human performance issues related to procedures, aircraft 

equipment, and information exchange. The left column of Table 1 provides a list of all categories 

considered. 

Many issues have a cause/effect relationship and therefore impact other areas. Some of them also 

have roots in more than one categorical area. In these cases, additional keywords are provided. Keywords 

may include the category labels or may come from an additional set of next level descriptors. The right 

column of Table 1 provides additional keywords. Some keywords are considered to be sub-categories and 

are listed under their corresponding higher level attribute. If an issue affects a specific keyword, the list 

references the keyword. However, if it affects several sub-categories under the same higher level category, 

the category may be listed in one of the keyword columns. Up to two keywords are provided for each 

issue. 
7

Table 1 Categories and Keywords Used in Issues List 

Category Keywords/Sub-Categories 

ATC Procedures 

Flight Crew Procedures 

Airline Procedures Pre-Departure Clearance (PDC) 

Training 

FMS (other than navigation database), 

Electronic Flight Instrumentation System 

(EFIS) 

Alerting 

Autopilot 

Distance Measuring Equipment (DME)/DME 

Inertial 

Equipment Capabilities 

Electronic Flight Bag (EFB) 

FMS Navigation Database 

RNAV SID/STAR 

RNAV Approaches 

RNP Approaches 

RNP Parallel Approach Transition (RPAT) 

Q Routes 

Procedure Design 

FMS Offsets 

Charting 

Chart/Database Commonality 

Approach Naming and 

Approach Classification 

Flight Plan Suffix 

NOTAMs 

Collaboration 

 Category organization within Table 1 is not necessarily based on order of importance, but has been 

chosen to facilitate description in later sections. Procedures can largely be broken down into those 

pertaining to pilots, air traffic controllers, and airlines. Pilot training and pre-departure clearance (PDC) 

formats are considered part of airline procedures. Equipment capabilities were often found to contribute to 

human performance issues. These instances included cases where pilots needed to accommodate the 

functional limitations of aircraft systems. Design issues have also been included. Due to the large number 

of entries pertaining to FMS navigation databases, these records are separated from other FMS functions 

such as guidance, flight planning, and aircraft performance. Procedure design is broken down into various 

en route and terminal procedures currently in use or proposed. Many issues were found that linked FMS 

navigation databases with the charts they supported. These issues are included as part of a separate 

category (Chart/Database Commonality). Approach Naming and Approach Classification includes both the 

distinction between precision and non-precision approaches as well as the approach naming convention. 

The latter is currently based on the type of equipment used to fly the approach, but may eventually 

incorporate a performance-based definition. Flight plan suffixes refer to the single letter codes used to 

identify relevant equipment capabilities onboard a particular aircraft. Notices to Airmen (NOTAMs) issues 
8

were captured that pertained specifically to RNAV and RNP systems and operations. Finally, several 

issues were documented concerning collaboration between various organizations making decisions on 

human factors for performance-based navigation. 

 Appendix A provides a priority assessment of each issue (high, medium, or low). Priorities were 

assigned based on expert review, time criticality, and potential for broad-reaching impact. Additional 

details of the prioritization scheme are provided in a later section. 

 The synopsis includes a summary description from the perspective of the person or entity raising 

the issue. It may not include other perspectives of the same issue, although those viewpoints may be 

captured as additional issues. Where possible, information is provided on known ongoing or previously 

occurring activities taken to address the issue. Due to the dynamic nature of this material and the large 

number of ongoing efforts, it is likely that some relevant activities have not been captured. Even when 

activities have taken place that are expected to provide complete resolution, the issues are still recorded in 

order to document lessons learned. These lessons may benefit stakeholders facing similar situations in the 

future and may also be helpful to other organizations (either domestic or international) at different stages of 

RNAV and RNP implementation. 

 

Issues List Findings 

 Issue descriptions below are described in the order listed in Table 1 and do not necessarily reflect 

order of importance. 

ATC Procedures 

 The introduction of RNAV and RNP procedures has led to opportunities for more route-oriented 

climb and descent clearances to be issued by ATC. A key advantage of RNAV SID and STAR procedures 

has been a reduction in vector and speed-based commands in the terminal area. These changes have 

improved efficiency and have generally reduced controller workload; however, they have also revealed 

several shortcomings in existing ATC terminology. 

One particular area that has caused pilot confusion relates to the distinction between a clearance to 

climb or descend uninhibited with one that requires compliance with intermediate altitude constraints. 

When the controller expects compliance with published constraints, the term, “descend via” is often used. 

There is no corresponding term for a climb scenario. Industry groups and controller personnel are currently 

working to address this gap through development of a “climb via” phraseology and procedure. Human 

factors validation testing is underway and training material is being developed in support of this procedure. 

Changes to the Controllers’ Handbook, 7110.65R7

 and the Aeronautical Information Manual (AIM),8

provide more specific guidance as it relates to “descend via” and runway transitions. These changes were 

motivated by the Pilot/Controllers Procedures & Phraseology Action Team under the PARC. The team is 

made up of FAA and industry subject experts. 

 Pilots have noted instances in ASRS records where they were confused by the controller’s altitude 

assignment while they were operating off the published portion of an arrival or departure procedure. 

Controllers should provide an altitude assignment while an aircraft is being vectored and state explicitly 

whether a flight crew should resume compliance with charted restrictions after re-joining the route. 

Changes to the Air Traffic Control Order7

 and AIM8 provide additional clarification on altitude 

assignments for cases where aircraft are cleared to proceed direct to a fix contained in a STAR procedure 

and then to “descend via” the arrival. These issues are also relevant for conventional SID and STAR 

procedures. 

 In response to changing air traffic needs, it sometimes becomes necessary for controllers to change 

the assigned runway for a departing or arriving aircraft. This change often requires the flight crew to 

perform several steps to re-program the aircraft’s FMS. Necessary changes include selecting a new 

runway, choosing a new runway transition, and clearing any resulting route discontinuities. Correct 
9

programming is even more important in an environment such as RNAV and RNP that emphasizes 

trajectory-based aircraft control close to the runway end. When multiple-runway operations are in effect, 

an aircraft’s flight path could conflict with other traffic if the route is improperly programmed. Reprogramming errors in operational service have led to path deviation errors and traffic conflicts. 

Performing the required changes can greatly increase crew workload, especially when at lower altitude or 

closer to the runway. Time pressures associated with immediate takeoff clearances can also be problematic 

when flight crews bypass essential FMS reprogramming verification. Focused training may be beneficial 

for both pilots and controllers. This training could emphasize proper and methodical re-programming by 

pilots and awareness by controllers to exercise caution when making changes during critical flight regimes. 

 Considering the programming changes that a crew must perform after a runway change, there is 

active discussion on ways that departing flights can be given information related to their runway 

assignment prior to push-back. The use of either Air Terminal Information Service (ATIS) or PDC has 

been discussed, but some have expressed concerns that these sources may cause confusion related to the 

clearance status of the information. 

 Another ATC change that can affect pilot performance occurs when a controller must change the 

altitude or speed assignment from that published on the chart. This revision often requires the aircraft to 

leave the FMS Vertical Navigation (VNAV) path and may make it more difficult to meet downstream 

waypoint altitude or speed restrictions. Controller training now emphasizes that pilots should be kept on 

the published procedure when possible. 

 ATC roles have also been discussed related to two en route RNAV procedures: “Q” routes and 

FMS offsets. Q routes are high altitude RNAV airways and FMS offsets allow pilots to fly their FMS paths 

at a specified offset left or right of course. A possibility exists that controllers may be asked to monitor the 

status of critical Distance Measuring Equipment (DME) stations for Q routes. Lost communication 

procedures are under discussion for FMS offsets. Any additional procedures for controllers should be 

considered in context of their existing duties. 

Flight Crew Procedures 

Flight crew procedures have also been substantially affected by the transition toward performancebased navigation. With generally more detailed procedures, controller expectations of repeatable and 

predictable flight paths, and requirements for additional programming, flight crews must remain even more 

vigilant. 

 Hand flying RNAV SIDs and STARs that contain multiple vertical constraints has likely 

contributed to altitude deviations. Autopilot use for multi-segmented procedures is recommended or 

required by several airlines. In addition to the use of autopilot, the choice of autoflight mode also 

contributes to the pilot’s ability to fly a precise path and meet restrictions. Establishment of a consistent 

engagement altitude for the Lateral Navigation (LNAV) mode has been recommended in order to improve 

path predictability. 

 Prior to conducting an RNAV or RNP procedure, pilots must verify that their equipment meets the 

proper requirements. For RNP procedures, they must be cognizant of the RNP requirement for each 

approach segment and must also monitor the aircraft’s Estimate of Position Uncertainty (EPU).1

 EPU 

relates to the ability of the aircraft’s position sensors to meet the accuracy requirements for a particular 

RNP level. The total system error, defined as the vector sum of the path definition, path steering, and 

position estimation errors, must be within the RNP value 95% of the time.1

 Current FMS equipment 

requires the pilot to enter the RNP value each time it changes for a new segment. These additional tasks 

have occasionally led to high crew workload. Near term additions to the navigation database will include 

RNP for enroute and approach segments. However, not all FMSs are capable of using the Navigation 

Database-provided RNP values. Regardless, the flight crew must ensure the charted RNP value is correctly 

entered into the FMS. 
10

Crew procedures must be tailored for the specific RNAV equipment used. For example, an RNAV 

SID performed with an Inertial Reference Unit (IRU) or DME/DME requires that the FMS be properly 

aligned prior to takeoff. Some pilots flying older aircraft without runway position updating have neglected 

to perform this task. This omission could result in a map shift shortly after departure and these map shifts 

have contributed to lateral deviations. Procedural mitigations have helped address this issue. 

Airline Procedures 

 Airline company procedures can affect pilot operations in the performance-based NAS. The most 

direct applications of this relationship include airline training programs and the issuance of PDCs. 

Pre-Departure Clearance (PDC) 

 Proper understanding of the aircraft and crew’s ability to fly particular RNAV and RNP procedures 

is important to ensuring that the resulting ATC clearance can be accepted by the flight crew. When the 

dispatch office files for a procedure that is unavailable to a particular aircraft type, potential errors can 

result when pilots obtain the clearance. 

 Problems may also ensue when the ATC clearance is different from the flight plan filed by the 

dispatch office. In several observed cases, the flight crews neglected to extract this important information 

when retrieving their clearance by PDC. In their ASRS reports, many pilots stated that the clearance 

change had been embedded in the footnotes or remarks section and had not drawn their attention. Pilots 

also cited preprogramming the FMS in anticipation of a preferred route or dispatch issued clearance and 

having not realized the PDC was different. In response to these concerns, some airlines have changed their 

PDC formats in order to highlight important changes. This issue is likely still a problem for airlines using 

older formats. 

Training 

Pilot training is frequently challenged by full syllabi and limited available time. For these reasons, 

airlines have traditionally been unable to spend substantial time covering the intricacies of FMS operations. 

Pilots often learn basic operations in class, but require on-the-line experience to become comfortable with 

additional features. These features may vary across different aircraft (even within the same model). 

Problems on RNAV procedures can occur when a crew has only received limited FMS training or lacks 

recent experience. High workload situations can develop on complex procedures, especially when a 

change requires substantial re-programming of the FMS route. Additional emphasis on overall flight 

management/autoflight system modes and transitions (including those related to the FMS) may also be 

warranted. Multiple successive altitude crossing restrictions associated with RNAV SIDs and STARs have 

led to altitude deviations when pilots were caught off guard by unexpected mode changes. Many airlines 

have responded to these challenges by developing specialized FMS RNAV courses and requiring flight 

crews to demonstrate proficiency in regular simulator sessions. 

Equipment Capabilities 

 Equipment design features and limitations often impact pilot performance and workload in a 

performance-based environment. Discussion of these issues is intended to guide system designers when 

developing new products or enhancing current ones, as well as to make pilots aware of their aircraft 

capabilities when conducting RNAV and RNP procedures. 

FMS (Other than Navigation Database) 

The FMS plays a key role in the implementation of performance-based navigation. Most FMS 

considerations related to RNAV and RNP operations primarily involve the navigation database. 

Nevertheless, the flight planning, trajectory generation, and guidance functions also have important roles. 
11

Pilots appear to have an easier time complying with speed and altitude waypoint constraints on 

RNAV and RNP terminal procedures when using the FMS VNAV capability. When engaged, the VNAV 

mode commands appropriate pitch changes to comply with these restrictions. Use of an autothrottle and 

autopilot in conjunction with VNAV enables pilots to monitor the aircraft’s altitude and speed without 

actively controlling to these targets. Pilots appear more susceptible to high workload events when these 

capabilities are unavailable or unused. 

When flying an instrument procedure with the FMS, pilots monitor their progress by keeping track 

of the active waypoint on the Legs/FPLN page or by referencing the Navigation (Moving Map) Display (if 

installed). RNAV and RNP procedures make more use of the fly-by and fly-over waypoint type 

distinctions than their conventional counterparts. Current FMS designs do not provide waypoint type 

information to the pilot. This information may enable better overall awareness during the procedure. Pilots 

should be aware of fly-by and fly-over waypoint designations on instrument charts and how they should be 

flown. As a general rule, fly-over waypoints are discouraged for most procedure design when repeatable 

and predictable flight tracks are required. 

Different FMS designs may vary in how they construct a path for a common waypoint type. 

During the initial implementation of RNAV departure procedures at Dallas Ft. Worth airport (DFW), wide 

variation in turn anticipation at a waypoint caused some aircraft types to overshoot the intended 

containment area. These path disparities occasionally led to traffic conflicts. Another potential difference 

is the way in which a FMS rejoins the outbound path after completing a large course change at a fly-over 

waypoint. These differences can contribute to air traffic separation issues when the resulting flight track 

differs from the controller’s expectation. Procedure designers and controllers will likely benefit from 

increased awareness of differences in tracking performance that exist among flight management systems. 

This information should enable them to better accommodate areas where design differences are most likely 

to contribute to path variation. 

Some flight management systems have design features that can cause unexpected behavior for 

pilots having less FMS proficiency or facing high workload situations. When a runway is selected on the 

FMS of Airbus aircraft, the FMS will automatically connect a programmed STAR with the runway using 

an approach transition (“Approach Via”) if one exists. This action will delete any STAR waypoints 

subsequent to the one commencing the transition. Pilots must ensure the resulting route is consistent with 

that intended by ATC. On Boeing aircraft, the FMS Route Page does not necessarily show all waypoints 

along the route. Pilots should therefore use the Legs Page (rather than the Route Page) to ensure that all 

desired waypoints are part of the active flight plan. When clearing a route discontinuity, using the Legs 

page may prevent unintentional waypoint deletion. This discussion is not intended to pass judgment on the 

desirability of these features, but rather to highlight areas that may deserve specific mention during pilot 

training. 

In other cases, concerns have been raised that some business and regional jets incorporate 

potentially challenging displays and interfaces. For example, the loaded runway may not be readily 

apparent on one regional jet’s FMS Nav page. On this same aircraft, pilots have had trouble fully 

understanding FMS error messages. Designers of these systems may benefit from a study that assesses the 

operational impact of specific FMS attributes. 

Tighter tolerances imposed by RNAV procedures sometimes challenge the capabilities of legacy 

systems. Two design features of a particular FMS have been mentioned with regard to their ability to 

manage waypoint speed constraints. These systems do not allow the pilot to enter a waypoint speed 

constraint without a crossing altitude. In addition, they disregard speed constraints after sequencing the 

corresponding waypoint. The former requires a pilot workaround, whereas the latter may affect aircraft 

tracking performance in a turn. It should be noted that these systems still provide highly reliable capability 

to conduct RNAV and RNP operations. 
12

Electronic Flight Instrumentation Systems (EFIS) 

 Sometimes the lack of a particular kind of equipment can affect flight operations as much as the 

characteristics of an available system. Pilots flying aircraft with pre-glass “steam gauges” are at a distinct 

disadvantage when flying RNAV and RNP procedures. The high speeds of commercial transport aircraft 

coupled with frequent turns and multiple altitude restrictions often make position situation awareness 

challenging. 

 Map displays that provide a situational representation of the aircraft’s position and corresponding 

navigation fixes allow pilots to anticipate course changes and monitor flight progress much easier than 

conventional course deviation instruments. Because of these issues, some airlines limit RNAV and RNP 

operations to those aircraft that have map displays associated with Electronic Flight Instrumentation 

Systems (EFIS). The importance of map displays may be even more pronounced for RNAV SIDs. On 

departure, the crew has less preparation time available to study the procedure and is often faced with even 

higher workload conditions than those occurring during RNAV STAR operations. 

 Display design issues are also emerging with the transition toward RNAV procedures. The 

additional flight segments contained in these procedures make it increasingly difficult for pilots to 

distinguish between the final approach and missed approach segments of an RNAV approach. In response 

to this issue, one aircraft manufacturer now specifies different colors to distinguish these approach 

segments. 

Alerting 

 RNP operations require alerting systems that indicate when the EPU has exceeded RNP. These 

alerts do not account for FTE and therefore do not notify the pilot that the aircraft position has exceeded the 

RNP value. On many aircraft, pilots monitor the aircraft’s position relative to RNP by referring to the FMS 

cross-track error on the Control Display Unit (CDU). Some have suggested this monitoring task would be 

easier if the cross-track error were displayed within the pilot’s primary field of view. This distinction may 

be even more important at low RNP levels. Boeing’s navigation performance scales are one potential 

design solution to this issue. 

 The navigation performance scales show the relationship between RNP, sensor performance 

(indicated as EPU, and available FTE). In addition to issuing containment advisories, they can be used to 

provide valuable trend information. Pilots have an immediate indication of degrading sensor performance 

when the additional position measurement uncertainty is shown to erode the margin available for FTE. The 

ability to which pilots are able to use this information may give valuable insight into the potential need for 

revised alerting system requirements. 

General design attributes of RNP alerting systems are currently under discussion. Many of the 

design issues are common with other types of alerting systems, including visual and aural cues, color, 

intensity, flash vs. steady state, and location within the pilot’s scan. Human performance studies such as 

those previously conducted for traffic, windshear, and terrain warning systems may be beneficial in 

establishing design criteria. 

Non-Satellite Position Sources 

 Aircraft without Global Navigation Satellite System (GNSS) equipment (such as Global 

Positioning System (GPS)) normally use Distance Measuring Equipment (DME) receivers for position 

information. Onboard DME equipment receives signals from multiple ground-based navigation aids and 

combines those signals to determine position. Many of these aircraft are also equipped with inertial 

systems that determine position by integrating acceleration along multiple axes. These systems have 

unique operating characteristics that can cause position sensing errors if not properly monitored and 

initialized. 

 A DME station is considered “critical” if its loss prevents the aircraft from making a proper 

position determination. Status of critical DMEs must be properly monitored to ensure that adequate backup 

procedures are initiated. Development of these backup procedures has been identified as an issue for 
13

RNAV SID/STARs and Q routes. Questions have been raised concerning whether pilots have adequate 

alerting mechanisms to indicate the loss of critical DME information. This issue will also be applicable to 

controllers if they are asked to monitor critical DMEs for Q routes as has been suggested. Controller 

workload issues may be important if they take on this additional task. Service volume saturation (high 

traffic density preventing proper reception) is an additional DME performance issue that should be 

considered for RNAV and RNP operations. 

Electronic Flight Bag (EFB) 

Electronic Flight Bags are being introduced as a means to provide an electronic depiction of 

charted instrument procedures. Studies are ongoing to consider the effects of depicting detailed chart 

information in an electronic format. Issues have been raised including display layout, readability, and the 

ease in which a pilot can navigate through various menus to access the desired procedure. The proper 

positioning of an EFB is also important. Flight deck engineers will need to consider different 

implementation solutions for different aircraft. 

FMS Navigation Database 

 The FMS navigation database is likely the equipment component that has the most broad-reaching 

impact on performance-based navigation. Among other capabilities, the navigation database is used to 

store and allow pilot access to departure and arrival procedures, approaches, and waypoint locations. When 

selected and executed by the pilot, these waypoints or procedures become part of the aircraft’s active flight 

plan. 

 An issue exists concerning the integrity of navigation information as it’s transformed from paper to 

a standardized electronic format and then converted into a customized file for each airline. Various errors 

or general compatibility problems can occur in each stage during this process. These problems can then 

lead to unintended consequences when pilots use the FMS to access navigation information and fly the 

selected route. 

Each country provides source navigation information to a database supplier that converts the data 

into electronic format. This source data may already contain errors when made available to the data 

supplier. Relocated navigation aids that were not properly updated in source data have led to map shifts. 

Potentially more serious consequences could be envisioned. 

The data supplier converts the source data into a standardized ARINC 424 format.9

 Errors can be 

introduced through the arduous process of converting written data to an electronic format. ARINC 424 

limitations add additional challenges to this process. Errors can also occur if the data supplier misinterprets 

the intent of the source data provider. In one case, a misinterpretation caused the data supplier to apply 

different coding to a missed approach segment from that intended, resulting in a completely new path that 

had not been previously checked for terrain clearance. In other cases, the source information may not be 

recorded in a format suitable for FMS processing. For instance, DME step-down fixes on an instrument 

approach are unnamed by the source. Consequently, these fixes must be assigned a name by the data 

supplier. This is one potential cause of a difference between charted and stored navigation data. 

Errors can also be introduced when the ARINC 424 data is converted into a FMS-readable format 

and provided to the airline as a customized file. Various FMS features and limitations may require changes 

to the original ARINC representations. The resulting work-around can lead to undesirable effects in some 

cases. Some FMSs do not support particular leg types. To accommodate this trait, the FMS manufacturer 

may need to substitute another leg type in place of the one that’s not supported. Other work-arounds may 

require the use of unconventional procedure naming. One FMS manufacturer that doesn’t support STAR 

runway transitions resorted to creating different named procedures corresponding to each runway 

transition. This unconventional naming may be confusing to pilots and could result in improper route 

selection. Some charted trajectory change points involving multiple conditions are generally not supported 

by any FMS. Certain procedures require the pilot to initiate a turn when first reaching either a waypoint or 
14

an altitude. Other unsupported conditional waypoints include those where the altitude crossing restriction 

or procedure segment itself changes based on the landing runway. 

Different coding techniques can cause significant variation in path construction and tracking. A 

recent study by Ottobre, O’Neill, and Herndon compared the effects of different FMS designs on path 

tracking performance.10 They cite one example where a Los Angeles RNAV SID was coded three different 

ways. These differences caused controllers to observe flight paths that were less consistent and predictable 

than they had anticipated when the procedures were introduced. Despite these differences, track variability 

has reduced significantly as a result of RNAV SID and STAR implementation. 

A process for FAA acceptance of navigation data quality standards at each step of this process with 

the exception of state-provided source data is now provided in Advisory Circular (AC) 20-153.11 This 

guidance is expected to mitigate prior errors that occurred during the data transition process.

Additional anomalies related to the final navigation database accessed by flight crews have been 

reported. Fixes, altitude crossing restrictions, runway transitions, and even entire procedures have been 

reported missing. In other cases, waypoints were erroneously added to a procedure or an incorrect 

waypoint identifier was used. These errors can lead to route discontinuities or deviation from the intended 

flight path. Some fixes share a common identifier. Flight crews must be vigilant to ensure proper selection 

of the desired fix. 

Navigation database errors may also influence an aircraft using VNAV on an approach. For both 

RNAV and conventional approaches, many flight management systems incorporate database information to 

generate a constant angle descent path to the Decision Altitude (DA). Although this VNAV path normally 

complies with all step-down altitudes, potential database or other FMS errors can lead to a constructed path 

that is below the charted step-downs. Additive FTE can further reduce obstacle clearances. When 

conducting VNAV approaches, pilots are required to use the barometric altimeter as the primary altitude 

reference source. In addition to tracking the path, they should monitor the aircraft altitude to ensure it 

remains above the step-downs. 

The navigation database is an incredibly powerful tool, enabling flight crews to access virtually any 

navigation aid or procedure in the world. The FMS and its supporting database significantly reduce pilot 

workload by allowing them to append entire procedures onto existing flight plans. They also keep track of 

complex coding information for a vast number of departure, arrival, and approach procedures. Because of 

these capabilities, pilots have come to rely greatly on the navigation database access features and the coded 

data they store. These systems are highly reliable. Nonetheless, it’s apparent that more work can be done 

to ensure the accuracy of source data and the proper representation of coded data in each FMS. Good 

suggestions have been raised in various forums. They include checks to verify accuracy of source data, 

combined with thorough validation procedures to ensure that each procedure can be correctly loaded and 

flown with predictable performance. More stringent criteria could be imposed for procedures in critical 

terrain or traffic environments. In addition to integrity checking, greater overall community awareness 

appears to be needed related to the consequences of different FMS designs on path tracking and flight crew 

performance. As RNAV and RNP procedures continue to propagate in the NAS, FMS design requirements 

may need to be revisited to ensure that necessary capabilities can be accommodated. 

Procedure Design 

 RNAV and RNP procedures span all segments of flight: departure, en route, arrival, and approach. 

Design of these procedures plays an important role in making sure that pilot and controller workload is 

manageable, human errors are kept to a minimum, and aircraft equipment enables pilots to fly the 

procedure as intended. These attributes are needed to achieve capacity goals while maintaining safety. 

This section describes design challenges and issues that have been raised for different types of RNAV and 

RNP procedures. 
15

RNAV SID/STAR 

 RNAV SID and STAR procedures offer airport planners greater flexibility to efficiently manage 

their airspace in the presence of constraints such as terrain, traffic from nearby airports, special use 

airspace, and noise restrictions. They also enable controllers to vertically separate arrivals and departures 

with fewer radio transmissions. Controllers are often able to clear an aircraft to comply with the charted 

profile instead of issuing successive level-off assignments. In order to accomplish these objectives, the 

procedures typically have more flight segments and waypoint constraints than their conventional 

counterparts. 

While RNAV terminal procedures are not inherently difficult to fly, pilots appear to fly them more 

effectively when their aircraft equipment, operating procedures, and training emphasize situation awareness 

for trajectory-based flight paths. Several in-service issues have occurred when pilots encountered a 

distracting event while already compensating for equipment-related or procedural challenges. Considering 

the higher workload associated with flight in a terminal area, such distractions are somewhat typical. In 

this flight regime, pilots balance procedure monitoring tasks with checklist usage, automation transitions, 

and configuration changes among other things. 

To maximize performance on RNAV SID and STAR procedures, it would likely be beneficial for 

designers to place additional emphasis on the operational impact of various procedure design attributes. 

Doing so would provide a greater margin for error when higher workload factors are present. Pilots and 

RNAV Task Force participants have identified high climb gradients, close waypoints, multiple speed and 

altitude restrictions in close succession, and unconventional at or below restrictions on climb-out as aspects 

that contribute to procedure complexity. Overall flyability may also be a factor for certain aircraft types. A 

Eurocontrol design guidance document emphasizes procedure validation to ensure flyability for all aircraft 

types intending to use the procedure.12 Even when flyable, design factors may contribute to human 

performance issues if pilot workload is adversely impacted. Pilots have raised concerns about their ability 

to see Visual Flight Rules (VFR) traffic beneath them when maintaining exceptionally high climb 

gradients. These requirements are often imposed in noise-sensitive areas. Questions have been raised 

about achieving the proper balance between these factors and airspace management goals. Further dialogue 

and coordinated decision making amongst all participants are needed. 

 Several additional design attributes may contribute to path deviation events. Large course changes 

incorporated within the procedure may cause overshoot problems, especially when these waypoints are 

placed close to the departure end of the runway. Turns close to the runway can be problematic for aircraft 

still accelerating on climb-out. Speed restrictions have been shown to help alleviate this problem. Speed 

restrictions, however, may delay configuration changes after takeoff. Close-in waypoints may also be an 

issue for non-GNSS equipped aircraft, such as those using DME/DME systems. These systems take a 

specified time to update the aircraft’s position once airborne. If this update hasn’t yet occurred by the time 

the first waypoint is reached, an overshoot may occur. Procedure designers should consider these tradeoffs. 

Good progress in this area has been accomplished as lessons learned have been applied to new procedure 

designs. 

Significant work is done to ensure that new RNAV procedures do not conflict with existing 

conventional ones. Nevertheless, an ASRS review revealed that traffic conflicts do occasionally occur as a 

result of disharmonized coordination between the two procedure types. Interference has also been 

mentioned relative to Military Operating Areas (MOAs). A review of specific issues may be warranted. 

 One observed pilot error can be traced to an RNAV procedure that shares a common name with a 

fix on another procedure. Pilots have mistaken clearance to the fix for clearance to fly the RNAV 

procedure. Several RNAV procedures may also share common initial segments with each other, causing 

some pilots to mistakenly select a different procedure. 

Because RNAV procedures enable direct point-to-point navigation without depending on the 

location of ground-based navigation aids, they often incorporate a higher number of waypoints. This 

increase leads to a greater probability that two different waypoints will sound similar over the radio (such 

as “BRAZI” intersection and “Bradley” VOR) or that the waypoint name is unpronounceable. Examples of 
16

the latter issue include waypoints named “EVXAF” and “TEYYI”. These issues may lead to unexpected 

turns if the aircraft proceeds to an unintended waypoint. 

FAA Orders 8260.46C13 and 7100.9D14 have been updated to provide some general human 

performance-related recommendations based on lessons learned. For example, both recommend limiting 

the use of fly-over waypoints. In addition, the RNAV Procedure Evaluation Team also considers some 

human performance issues when developing a new procedure. These efforts continue to improve an 

already high level of operational performance. 

Even with these gains, it appears that procedure designers would benefit from a specific and 

comprehensive set of guidelines that concentrates on human performance. These guidelines could 

consolidate lessons-learned to date as well as incorporate any additional issues raised in human factors 

studies. Covered areas may include the use of speed restrictions, amount of course change, the number of 

course changes, and the proximity and number of successive altitude crossing restrictions. Incorporating 

these considerations into the design process could make it easier for designers to accommodate both air 

traffic and operational issues. In addition, this knowledge may be helpful to other countries implementing 

RNAV procedures. 

RNAV Approaches 

 Aircraft equipped with VNAV enable flight crews to fly a constant flight path angle descent from 

the final approach fix to the missed approach point, leading to more stable approaches when an electronic 

glide path would not otherwise be available. VNAV approach guidance is fundamentally different from the 

technique used to fly a conventional “non-precision” approach without a published glide path angle. A 

VNAV descent replaces the need to “dive and drive”, a process by which the aircraft descends and levelsoff at each successive step-down fix. “Baro VNAV” aircraft incorporate the approach-specific glide path 

angle into the VNAV path when the approach is loaded. 

When a VNAV glide path angle is used in place of progressive step-downs, operators may be 

approved to use a Decision Altitude (DA) in place of the Minimum Descent Altitude (MDA). Operators 

should ensure that pilots know whether this replacement has been authorized and the appropriate minima to 

use. In cases where a DA is not already published, some countries require an add-on to account for the dip 

below the DA that may occur when executing a missed approach. 

RNAV approaches typically provide both LNAV MDA and LNAV/VNAV DA minima. To avoid 

potential confusion, it would be helpful for pilots to understand the rationale behind higher minima 

associated with the LNAV/VNAV DA. Although the approach with glide path offers higher precision and 

a more stable approach, it incorporates different obstacle clearance criteria under the United States 

Standard for Terminal Instrument Procedures (TERPS).15 

 A significant issue undergoing serious consideration within the RNAV community concerns the 

feasibility of designing an approach where DA is reached in a turn. This design choice would represent a 

considerable change from current operations where the missed approach point is always part of a straight 

segment and is normally aligned with the runway. Important questions to be addressed include the pilot’s 

ability to maintain adequate visual contact with the runway environment when reaching the DA. During a 

turning final segment, the runway will not align with the direction of flight. This offset may introduce 

perception issues when viewing the Visual Approach Slope Indicator (VASI), Precision Approach Path 

Indicator (PAPI), or the runway itself. Will pilots be disoriented when faced with this environment 

immediately upon exiting the clouds? Another concern relates to the aircraft response during the initial 

part of a potential go-around. When activated, the Takeoff Go Around (TOGA) buttons on older Boeing 

aircraft command a wings level flight attitude. This bank angle change could cause the aircraft to leave the 

desired flight path. Flight crew awareness and performance aspects will need to be evaluated. 

 Additional design issues include a potential maximum turn angle at the final approach fix and the 

length of the final approach segment. Both of these attributes contribute to the conventional definition of a 

stabilized approach. 
17

RNP Approaches 

 Tight linear containment regions and guaranteed path tracking performance associated with RNP 

enable procedure designers to construct published routes through highly constrained airspace environments. 

RNP greatly increases safety by aligning an aircraft’s path tracking performance with the demands of a 

given procedure. With these new capabilities, traditional definitions of a “stabilized” approach are being 

reevaluated. Airlines have typically required that their aircraft be in straight flight at constant flight path 

angle and thrust setting and in final configuration while on the final approach segment. Deviation from 

these conditions would require an immediate missed approach. RNP procedures offer the opportunity to 

design segments that incorporate curved paths and changing flight path angles. This flexibility enables 

procedure designers to make the most use of available airspace and to achieve the lowest possible 

minimums. Along these lines, a new definition of “stabilized approach” has been proposed: “an approach 

where the aircraft is in the landing configuration and the lateral and vertical trajectories are managed by the 

automation system and predictable to the operator.” Whether or not this new definition or some variant is 

acceptable to the airline community and to regulators is a subject of future discussion. 

 Several turning segment issues are under consideration for RNP approaches. The “DA in a turn” 

issue discussed for RNAV approaches is also applicable to RNP procedures. Questions exist concerning 

the requirement for a straight segment before and after DA. If a straight segment is required, how long 

should it be? Additional questions concerning turning segments include the appropriate minimum altitude 

for a turn, the minimum altitude for the aircraft to be aligned with the runway centerline, and the proper 

length of straight segments that precede Radius to Fix (RF) legs on final approach. Aircraft flying at higher 

approach speeds will have a more difficult time complying with tight turn radius requirements for RF legs. 

A method is needed to ensure these limits can be met for all aircraft that may fly the procedure. FAA 

documents such as Order 8260.5216 provide guidance to procedure designers on these areas. Human 

performance studies are ongoing to explore evolution of these criteria for turning segments. 

 ARINC 424 publishes numerous leg types and path terminators.9

 Certain leg types may be more 

susceptible to the FMS design variation discussed above. To ensure acceptable path conformance for all 

aircraft types using the procedure, guidelines are needed for design decisions such as the use of a particular 

leg type or the choice of one over another. Nonetheless, several members of the airline community have 

concerns that procedures designed for “lowest common denominator” equipment do not allow those 

airlines with more sophisticated FMS/RNAV systems to get full use out of their capabilities. 

 During the initial implementation of RNP, all RNP operations were customized for each particular 

airline. The overall operation included aspects such as the procedure design, flight crew training, use of 

automation, and checklists. RNP operations were designed to accommodate an airline’s unique fleet type, 

operational procedures, and particular airports served. As procedures are now being implemented for 

public use (subject to Special Aircrew and Authorization Required [SAAAR]), it will be necessary to 

ensure they are designed in a way that accommodates all airlines and aircraft that may use them. These 

public procedures must be able to accommodate multiple flight deck platforms, FMS types, and flight crew 

procedures. Procedure design and operational guidance are currently provided by FAA documents such as 

Order 8260.5216, AC 90-101,17, AC 120-29A,18 and individual airline “Op Specs”. Some highly complex 

procedures may need to remain airline-specific. Criteria are also needed to support this decision. 

RNP Parallel Approach Transition (RPAT) 

 RPAT is an operational concept currently under development and evaluation. It involves 

simultaneous parallel runway operations with one aircraft flying an ILS approach and the other conducting 

an RNP procedure. RPAT is conducted in weather conditions sufficient to allow the RNP aircraft to 

visually acquire the ILS traffic before crossing the final approach fix. The RNP traffic must execute a 

missed approach if it doesn’t have the ILS traffic in sight by this point. A potential human performance 

issue relates to the ability of the RNP aircraft to consistently acquire the ILS traffic while conducting its 

own approach under marginal VFR weather conditions. 
18

En Route Procedures 

 In general, pilot workload doesn’t present as many challenges to designers of en route procedures 

as it does to those supporting the terminal area. Nonetheless, en route procedures such as Q routes and 

FMS offsets should be designed to allow adequate fallback options if a system failure or other condition 

prevents the procedure from being flown as intended. Radar procedures generally provide risk mitigation 

for these operations. 

Charting 

 To this point, discussion of RNAV procedures has related to operational and equipment aspects for 

pilots and controllers. Representation of these procedures onto paper or electronic media also encompasses 

a number of human performance-related issues. 

 When required information elements are added to RNAV SIDs and STARs having multiple paths 

and flight segments, the resulting charts can become cluttered. In turn, clutter can create the appearance of 

higher complexity. These charts can cause excessive search time, higher workload, and an increased 

chance of an interpretation error. A chart that has limited white space can be difficult to read and locate 

important pieces of information. 

Chart clutter can be attributed to a number of different factors. It may be the result of an overly 

complicated procedure design, an abundance of required information elements, or inefficient use of 

available space. It may be helpful to review current procedures to ensure they achieve the proper balance 

between air traffic and operational needs. Specific attention to charts that incorporate many of the design 

attributes discussed above may be warranted. In many cases, it appears that traditional rules for providing 

some types of information and apparently trivial distinctions can seriously impact an RNAV chart. For 

example, one RNAV SID depicts four heading to altitude waypoints in close proximity. All four waypoints 

give an altitude where the turn should be initiated that is within 20 feet of a cardinal altitude. Because of 

this seemingly insignificant distinction, separate arrows and altitude text boxes must be provided. In other 

cases, a long laundry list of low height obstacles takes up valuable chart real estate. These obstacles are 

often well off the charted path and do not appear to present an operational hazard. To accommodate this 

issue, it may be necessary to revisit some existing protocols for providing these types of information. 

 Lack of display “real estate” can lead to other problems. Without sufficient space, chart designers 

often must resort to putting information where they can find an available spot instead of a more optimal or 

consistent location. Altitude crossing restrictions for some charts have been placed well away from the 

waypoint they represent. In addition, busy charts often necessitate the use of extremely small font size. It’s 

questionable whether some information can be readily retrieved from charts under challenging conditions 

such as at night or in turbulence. 

 It may be beneficial to re-consider chart formatting techniques in cases where there’s no 

compelling visual difference between two symbols or text boxes that have an important distinction. For 

example, it may be difficult to immediately distinguish between text boxes that indicate “at or above” or “at 

or below” altitude restrictions. In an ASRS review of RNAV SIDs in Las Vegas, pilots often failed to 

notice an unconventional at or below altitude restriction. This restriction is necessary to keep departures 

separated from incoming arrivals. 

 Chart formatting may lead to confusion when different formats are used to describe the same thing. 

For instance, one chart source has two different ways to indicate an altitude crossing restriction. It’s 

depicted as “cross at” followed by the altitude on some charts and as an altitude with a bar above and below 

it on others. For some charts, inconsistencies have also been observed between the depicted procedure and 

the corresponding textual description. 

 In other cases, the choice of wording on a chart may lead to confusion. A recent issue emerged in 

Atlanta when pilots misinterpreted instructions for “aircraft departing north” to mean aircraft that are flying 

to a destination north of Atlanta. Instead, the instructions were meant to apply to aircraft departing the 
19

local Atlanta area on an initial northerly heading. This problem could probably be addressed with a simple 

wording change. 

 Wording choice has also been raised as a potential source of confusion for RNAV approaches. 

These charts currently provide “LNAV” and “LNAV/VNAV” minimums. “LNAV” and “VNAV” also 

describe autoflight modes on some aircraft. Use of the same abbreviators to refer to two different things 

could cause confusion. It may also provide an unintended link between a charted procedure and a 

particular type of equipment. 

Several concerns relate to the use of “LNAV/VNAV NA” in the minimums line. Pilots have 

interpreted this notation to mean that use of VNAV is not authorized on the approach. On some charts, this 

notation is used even when a final approach flight path angle is depicted. In these cases, it appears that the 

procedure can’t be flown as depicted. Even without a published glide path angle, pilots are allowed to use 

VNAV provided they remain at or above the step-down altitudes. In actuality, RNAV Task Force 

discussion revealed the notation only means that LNAV/VNAV minima are not available. It doesn’t limit 

the use of VNAV for the approach. Similar confusion has resulted from use of “LNAV/VNAV” with a 

corresponding blank line. 

RNAV equipment is often an allowable substitute for sensors that rely on ground-based navigation 

aids. One chart note, “ADF Required”, can be confusing for operators with equivalent capability. It’s been 

suggested that this note be changed to “ADF or equivalent capability required”. This case may be an 

example of a conventional note that has not kept pace with the proliferation of new allowances for RNAV 

capabilities. 

 Many RNAV SIDs have a “top altitude”. This altitude represents the vertical clearance limit for 

the procedure. It is often the altitude limit provided to pilots on their initial clearance. Confusion can arise 

when an altitude crossing restriction on the procedure is greater than the top altitude. In this case, it 

appears that the chart is internally inconsistent and cannot be flown as depicted. This disparity can cause 

concern when pilots are unaware of the reason behind the crossing restriction. One example of this issue 

occurs on a Las Vegas RNAV SID. In a discussion, FAA personnel indicated that a restriction is needed to 

ensure DME coverage for DME/DME aircraft. It’s not needed to maintain terrain clearance. 

It may be possible to use charted procedure supplements to make pilots aware of general 

information that encompasses operational, equipment, and charting aspects of RNAV procedures. One 

suggestion under consideration would provide a departure operations page at the beginning of each set of 

RNAV SID and STAR procedures for a given airport. This page could cover general areas such as the 

need to ensure proper FMS programming as well as any specific local issues. 

Human factors experts have provided some recommendations for chart designers of RNP approach 

procedures. These charts should be consistent, have minimum clutter, be readable, and support planning. 

Along these lines, it is recommended that a chart’s textual description depict waypoint fly-by/fly-over 

status. It may also be helpful to depict flight track graphically for some leg types. 

Chart depiction is often rooted in the procedure design itself. Nevertheless, charts play a 

substantial role in ensuring that pilots understand the procedure, are able to readily extract necessary 

information, and fly it as intended. Development of both procedure and chart design guidelines would help 

to achieve these goals. 

Chart/Database Commonality 

Consistent representation of procedure information between the FMS navigation database and the 

chart is essential to mitigating excessive flight crew workload and potentially hazardous operational errors. 

This issue gained international prominence after the crash of American Airlines Flight 965 in Cali, 

Colombia on December 20, 1995.19 

While approaching Cali, the flight crew intended to program the ROZO NDB (located near the 

airport) into the FMS. On the chart, this fix is identified by the letter ‘R’, but the navigation database 

recognizes it as ‘ROZO’. When the crew programmed ‘R’ into the FMS (instead of “ROZO”), the database 
20

loaded the ‘ROMEO’ NDB into the active flight plan. ‘ROMEO’ is another NDB well off course to the 

east that is also indicated by the letter ‘R’ on the chart. The resulting route took the aircraft off the intended 

path and it impacted terrain. In response to this accident, the NTSB recommended that approach charts, 

FMS navigation databases, and electronic map displays provide a consistent representation of navigation 

information.20 

 Discrepancies between charts and databases continue to exist today. Some fixes on the chart are 

still not the same as the corresponding fix in the database. One example of this type of discrepancy exists 

when DME fixes are used as step-downs on an approach. The chart may only list the DME distance at each 

point because a waypoint name has not been established. In order to store these fixes in the database, the 

navigation data supplier must choose a name. Pilots looking at these fixes on both the map display or FMS 

Legs page and the chart will see different representations of the same point. 

When multiple approaches of the same type exist to the same runway and airport, the FAA and 

ICAO append a “multiple indicator” (-Z, -Y, etc.) to the approach name. These indicators start from the 

end of the alphabet, with one letter being assigned to each approach. Their use has become more prevalent 

as RNAV approaches have been added. Because the multiple indicator is a recent addition to ARINC 424, 

many flight management systems are not yet able to accommodate it. When using these systems, pilots 

won’t necessarily know which approach that has been loaded. The procedure name shown on the FMS 

Procedures page will not match the approach name indicated on the chart. Criteria are needed to establish a 

specified approach in the series that will load by default when the pilot selects an approach for a runway 

containing multiple procedures of the same type. This default must be mutually understood between the 

pilot, operator, and navigation data provider. As an alternative, some are proposing a reduction in the 

number of common type approaches to the same runway. For example, multiple RNP-based approaches 

with a common missed approach segment could be incorporated into a single chart incorporating different 

minima for each supported RNP level. 

 FMS navigation databases can also be used to provide supplemental information for most 

conventional procedures. A FAA notice recommends that operators pay particular attention to their flight 

track when using FMS guidance for non-RNAV procedures. 

Approach Naming and Approach Classification 

Most instrument approaches are currently named based on the sensor equipment that supports 

them. This convention has led to the proliferation of approach names including ILS, VOR, NDB, LOC, 

LDA, SDF, and many others. This naming convention appears to be inconsistent with a performance-based 

environment that intends to focus on capabilities rather than the types of equipment used. The vast number 

of approach types can lead to complications for airlines needing to provide training and proficiency 

opportunities for their pilots. 

The current approach classification system can lead to confusion when pilots must determine how 

new technologies on their aircraft fit into the regulatory structure of existing conventions. Approaches 

have historically been grouped into broad classifications that specify general characteristics of the type of 

guidance they provide. This classification includes two types: “precision” and “non-precision.” These 

definitions are still officially recognized by ICAO and remain embedded in FAA regulations. Precision 

approaches such as ILS and GNSS Landing System (GLS) are required to meet certain ICAO requirements 

for a vertical glide path. “Non-precision” approaches have traditionally only provided lateral guidance. 

Approaches with vertical guidance incorporating other GNSS-sensor supported glide paths (such as Wide 

Area Augmentation System (WAAS)) or non-GNSS Baro VNAV systems do not qualify as “precision”. 

 Discussion is underway to consider changing this classification system to one that is more intuitive 

for all users and more inclusive of new technologies. Concatenation of current approach types into a 

system that focuses on RNAV, RNP, and “xLS” may enable a more dedicated focus to the operational 

capability offered by each approach type. The term “xLS” refers to an approach type that supports an 

autoland capability (such as ILS, MLS, or GLS). 
21

A more direct relationship between an approach type and its derived minima is another potential 

benefit of a new classification system. One example of the lack of connection between legacy approach 

types and operational capability is the prevalence of RNAV approaches with higher LNAV/VNAV minima 

than those offered by traditional approaches to the same runway. A re-classification should enable 

operators to derive more utility from their equipment investments, while affording greater overall 

simplicity. 

 The FAA and some manufacturers have already taken steps to phase out the older definitions. 

FAA AC 120-29A explicitly avoids the terms “precision” and “non-precision”.18 It provides a new 

classification system consisting of 3 areas: “xLS”, “RNAV”, and “Instrument Procedures Other Than xLS 

or RNAV.” These descriptors are more closely aligned with associated levels of navigation performance 

capability. Currently, only xLS is authorized for Category II weather minima (not lower than 100 ft).18 

“RNAV” includes provisions for different levels of RNP and can be further broken down into 3D 

(LNAV/VNAV) and 2D (LNAV). The “Other” category includes traditional procedures such as VOR and 

NDB and applies when they are flown using raw navigation data from the named sensor system. 

Organizations and committees such as the International Air Transport Association (IATA) and the 

All Weather Operations Harmonization Working Group (AWO HWG) are also supporting changes to 

existing ICAO definitions. One such proposal for the near to mid-term aligns with the AC 120-29A 

definitions. Eventually, this classification may be further simplified to 3D (xLS, RNAV (RNP), and 

RNAV with LNAV/VNAV minima) and 2D procedures (those using an MDA). 

With these potential benefits in mind, there are also a number of considerable challenges that result 

from ongoing efforts to change the approach classification system. The legacy system is internationally 

established and is widely distributed across a range of documentation, regulations, and operational 

procedures. Some affected areas include training documents, airport lighting, airspace protection, obstacle 

assessment, airspace design, and alternate minima requirements. Some have raised concerns about a 

potential classification change. One FMS manufacturer raised the possibility that a re-classification of 

VNAV approaches under a higher category could require the FMS to be certified at a more stringent level, 

thereby increasing costs. If such a change is to be considered, a comprehensive effort to determine all areas 

affected by the current system would clearly be needed. 

Flight Plan Suffixes 

 Controllers must rely on single letter codes (flight plan suffixes) to determine whether an aircraft 

meets the requirements for performing a particular operation. FAA and industry representatives have 

raised concerns that current flight plan suffixes do not meet the needs of a performance-based navigation 

system. Comparable to the current approach naming convention, these suffixes normally indicate the 

equipment on board an aircraft rather than an available capability. Although some of these suffixes directly 

relate to a capability (such as those referring to Reduced Vertical Separation Minima (RVSM)), many of 

them only indicate the type of equipment onboard. Controllers must then determine whether an operation 

can be performed based on the presence of certain types of equipment. They often lack sufficient 

information to make this assessment. When clearances are issued for an operation that an aircraft cannot 

support, workload is increased for both pilots and controllers. In these cases, controllers must often work 

out a new plan that involves a different procedure and flight crews must review and re-program that 

procedure. These problems also occur when the ATC host computer assigns a procedure to a flight plan 

that the aircraft cannot support. 

These issues are likely to become more common as the number of equipment combinations and 

operational capabilities continues to increase. The proliferation of different RNAV and RNP procedures 

may quickly overwhelm the capability of controllers to make reasonable assessments of aircraft capability 

based on the current suffix system. For example, some RNAV approaches do not allow the use of 

DME/DME. Aircraft with /E or /F equipment are not allowed to fly “GPS” Approaches.18 There is also no 

direct correlation between a current flight plan suffix and the ability to fly a Q route. A single suffix is 
22

currently used to indicate RNP capability. RNP requirements vary between some procedures and there is 

no means for a controller to determine an aircraft’s RNP level. Changing to an approach classification 

system where a single procedure is used for multiple RNP levels would alleviate this problem. 

Flight plan suffix ambiguities also extend to pilots and operators. Pilots must be aware of their 

ability to accept an assigned procedure. Confusion with an equipment-based suffix system can also exist 

when a particular piece of equipment doesn’t align with those referenced in the suffix list. Past FAA 

documentation indicates that some operators have mistakenly taken /F credit (indicates FMS capability) 

when equipped with only an Attitude Heading Reference System (AHRS). The AHRS does not provide a 

path tracking capability that meets FMS standards. 

Although recently changed to recognize RVSM capability, the current flight plan suffixes are likely 

inadequate to meet the needs of a performance-based NAS. These limitations will become more apparent 

as performance-based operations extend to communication and surveillance capabilities as outlined by the 

JPDO.4

 Steps taken to re-structure the flight plan suffixes should be internationally coordinated as U.S. 

and ICAO suffixes currently do not align. 

 

NOTAMs 

Pilots have long raised concerns over the ability of the NOTAM system to effectively disseminate 

timely information. NOTAM information can be difficult to access and its format is often hard to read and 

understand. Important NOTAMs are often embedded in a long list of items having less apparent 

operational significance. For example, pilots have voiced opposition to including extensive lists of low 

height obstructions far from any likely path. This “low signal to noise ratio” can cause aircraft operators 

and pilots to miss important information. 

In a performance-based NAS, NOTAMs will increasingly be used to inform pilots about degraded 

capabilities of key navigation infrastructure. They may also be needed for aircraft system-related problems 

such as navigation database errors. The dynamic nature of this information will likely place even higher 

demand on efficient and accurate information retrieval. 

 As RNAV and RNP procedures are evolving, the NOTAM system should be reviewed for its 

ability to provide sufficient supporting information that allows pilots to make operational decisions. A 

specific concern relates to the information available if the Department of Defense degrades the GPS signal. 

NOTAMs must be able to provide pilots and operators with the proper information in a format that can be 

readily accessed. 

Issues List Prioritization 

Prioritization Criteria 

 Priority assignments (high, medium, and low) are provided for each issue listed in Appendix A. 

The priorities were assigned based on the following criteria: 

• Level of importance assigned by the PARC Human Factors Working Group. This working 

group assigned attributes of the most important issues during a July 2005 Working Group 

meeting. Issues identified as important included those that 

o have been asked for by a PARC working group or action team; 

o support regulatory material development; 

o address a significant safety issue in the implementation of performance-based airspace; 

o and those where an opportunity exists to affect change in a timely way. 

• Prevalence of issues mentioned in various forums. 

• Existence of broad-reaching impact considered fundamental to performance-based navigation. 

• Level of importance assigned by expert users during interviews. 

In general, if an issue rated highly in any of these factors, it was given a “high” rating. 
23

If no attribute emerged as being particularly strong, it received a “medium” rating. Issues that were 

considered applicable to a smaller group of users and deemed to have only minimum consequence received 

a "low" rating. New thrusts in the RNAV/RNP community or the development of new operational 

procedures could potentially change the ratings. A total of 259 issues were identified: 144 high, 96 

medium, and 19 low. 

Recommendations for Earliest Consideration 

 Several high-rated issues are recommended for near-term studies by government/industry 

committees and research organizations. For these issues, answers to important human factors or design 

questions are desirable in order to further improve overall operational performance and mitigate error. 

Human Factors Guidelines for RNAV/RNP Instrument Procedure Design 

It appears that procedure design techniques are currently based primarily on obstacle clearance 

assessments, minimum reception altitudes, noise restrictions, and traffic flow management issues, with less 

emphasis being placed on operational human factors. Eurocontrol’s design document emphasizes the 

flyability of RNAV terminal area procedures and clarifies it is not intended to directly address operational 

issues.12 Changes to FAA Orders 8260.46C13 and 7100.9D14 pertaining to SIDs and STARs do provide 

some awareness of human performance issues based on lessons learned.

Terminal area and approach procedure designers would likely benefit from a set of comprehensive 

and specific design guidelines that consider flight crew and controller performance. These guidelines could 

be used as part of an overall package evaluated prior to the development of a new RNAV procedure. They 

could also be applied to current procedures, with recommendations made for improvement. Guidelines 

should consider the human performance effects of design attributes discussed in this report and the 

accompanying Issues List. Attributes include but are not limited to climb gradients, waypoint proximity, 

the use of successive altitude restrictions, and DA in a turn. They should also consider ways for common 

elements between similar procedures at an airport to be evaluated for their potential to cause 

misidentification (capture) errors. 

The guidelines should be supported by a series of studies that identify tradeoffs between different 

design techniques, propose recommended limits, and consider interaction effects. 

An assessment should be made of current design techniques for their impact on human performance. 

 Considering the negative effects of high overall complexity, a study is recommended to develop a 

procedure complexity metric. FAA Orders 8260.46C13 and 7100.9D14 mention the importance of low 

complexity but do not seem to offer a specific metric. An effort should also be made to assess the effects 

of common design techniques and their interactions on overall complexity. Recognizing that different 

airports present various design challenges, a review process is recommended for procedures that exceed a 

defined complexity threshold. 

Identification of Lessons Learned during RNP SAAAR Experience and Recommendations for 

Implementation of Public RNP Procedures 

 Considerable operational experience has been obtained by airlines that currently fly speciallytailored RNP procedures. These procedures as well as procedures proposed for public use fall under the 

category “Special Aircraft and Aircrew Authorization Required (SAAAR)”. Some companies such as 

Naverus specialize in developing tailored RNP procedures for airline customers. An effort should be made 

to ensure that recommendations for transitioning toward public RNP procedures capture lessons learned 

from prior experience in RNP procedure design, flight crew operations, and training. These 

recommendations should also include complexity guidelines that may require the procedure to be used only 

when specially designed for an airline or other operator. Procedure design recommendations can be used to 

support the broader effort on RNAV/RNP procedure design guidelines discussed above. 
24

Continuation of and Coordination among Working Groups that Identify and Propose Solutions 

for Operational Problems Associated with RNAV SID/STAR Procedures 

 A number of highly beneficial activities are currently ongoing in various working groups to 

identify and mitigate operational problems that have occurred on some RNAV SID and STAR procedures. 

The RNAV Task Force, RNAV Procedure Evaluation Team, PARC, and ICAO are examples of groups 

supporting these activities. These groups consist of a broad spectrum of NAS stakeholders, including 

pilots, controllers, navigation data providers, avionics and airframe manufacturers, and government 

agencies. Efforts are currently underway to conduct human factors studies to consider the effects of 

proposed new ATC terminology as well as to recommend targeted areas for pilot and controller awareness. 

Included in these activities are implementation studies of “climb via” terminology and consideration of 

ways to inform pilots and controllers about issues associated with runway change assignments. Strong 

collaboration among groups addressing these issues is needed to ensure harmonized solutions and effective 

allocation of resources. 

Consideration of Potential Changes to Approach Naming, Approach Classification, and Flight 

Plan Suffixes 

 A coordinated effort should be undertaken to consider the potential benefits and impact of a 

significant change to the approach naming, approach classification, and flight plan suffix systems. The 

group undertaking this project should have representation from the full spectrum of NAS stakeholders. It is 

recommended that this process begin with a detailed assessment of perceived problems associated with 

current day systems. It should also provide a comprehensive list of all documents, training programs, 

regulations, procedures, and any other areas that would be affected by a potential change. Considering the 

problem and impact assessments, an analysis of different change options could be undertaken. If the group 

determines that a change is warranted, it could consider working through existing committees to submit a 

proposal to ICAO. As noted earlier, ICAO is currently considering some proposals in these areas. 

Resolution of High Priority Items Concerning Chart/Database Commonality 

 The FAA and data suppliers should continue work to resolve differences between navigation 

databases and published charts. High priority should be given to specific recommendations issued by the 

NTSB. One presentation from a data supplier indicated that more assistance from the FAA is required in 

order to address some of these recommendations. Assignment of waypoint names to DME fixes used on 

instrument approach charts has also been identified as an important issue. 

Review of Aircraft Equipment-Related Impact of RNAV and RNP Operational Events 

 A comprehensive review of problematic operational events attributed to equipment-related factors 

should be undertaken for RNAV SIDs and STARs, RNAV approaches, and RNP approaches. 

Consideration should also be extended to cases where the absence or non-use of a particular system may 

have played a role. If this review reveals common deficiencies, the FAA should consider revising the 

appropriate documentation. 

In this review, the use of electronic map displays for RNAV/RNP should receive particular 

attention. NASA’s preliminary review of RNAV SID/STAR procedures found that pilots often mentioned 

the lack of a map display as a contributing factor to high workload and error conditions. FMS interface, 

display, and alerting issues should be considered. The effect of flight management systems to handle 

particular leg types and path terminators on flight crew performance and procedure design would also be of 

interest. Many of these factors are being discussed by the Flight Deck Automation Working Group. 

Review of Issues Pertaining to Use of Baro VNAV during Instrument Approaches 

 Airlines have found that the use of electronic glide paths provided by Baro VNAV leads to more 

stable approaches, higher precision, and lower pilot workload. Considering these advantages, two primary 

issues emerged related to the use of Baro VNAV for instrument approach procedures: selection of 
25

appropriate decision altitudes and terminology used on the LNAV/VNAV minima line. It would be 

beneficial for procedure designers to compare established minima for existing non-precision approaches 

with those of comparable LNAV/VNAV minima for RNAV approaches. In government/industry meetings, 

several members of the airline community were unclear of the rationale for establishing higher minima for 

LNAV/VNAV supported approaches than those in place for current non-RNAV approaches without 

vertical guidance. Any inconsistencies in minima application should be clarified or resolved. 

 Efforts should be taken to review and clarify the use of “NA” or a blank space on the 

LNAV/VNAV minima line for RNAV approaches. Several airline committee members have stated that 

this usage leads pilots to believe that VNAV is not authorized for the approach. This confusion may 

prevent pilots or operators from taking advantage of the safety and performance benefits associated with 

Baro VNAV. 

 

Selection of Targeted Studies 

 When considering a particular area of concentration for more detailed study, researchers, industry 

representatives, and government officials should consider a number of different factors. Among these 

factors include the existence of ongoing studies, current priorities, available resources, and time available. 

In some cases, it may be advantageous to consider bypassing a significant, broad-reaching issue that will 

require substantial resources in favor of one that has somewhat less impact, but can be greatly mitigated 

with a smaller-scope effort. 

 Availability of necessary infrastructure and personnel are also likely to be major factors when 

considering targeted studies. Issues that require a detailed assessment of flight crew performance will 

necessarily require high fidelity simulators that are able to replicate observed or anticipated operational 

challenges. For example, the “DA in a turn” issue described above will require a flight simulator that has 

highly realistic visual effects. Motion may also be required in order to simulate potential interactions 

between visual and sensory perception. Issues relating to controller phraseology will certainly require the 

participation of air traffic personnel. 

 In many cases, proper treatment of an issue will require joint efforts from a diverse group of 

specialists. For example, efforts to produce recommended guidelines for instrument procedure design 

should at least include pilots, air traffic controllers, procedure designers, and regulators. Each group will 

bring a different perspective, thus enabling the group recommendations to properly balance the needs of all 

parties. 

 Any effort to address a human factors issue should only be undertaken after careful review of 

ongoing work by other government/industry committees and research organizations. After starting such an 

effort, the community would likely benefit from remaining apprised of the latest operational trends and the 

continued relevance of the issue under consideration. Advancements in system capabilities or operational 

procedures may change the characteristics of an issue. These changes may require the study to shift focus. 

Conclusions 

 A substantial transformation to a performance-based navigation system is underway worldwide. 

New RNAV and RNP procedures are being developed and implemented at a rapid pace. Benefits offered 

by these procedures are extensive and are being realized by both operators and air traffic service providers. 

The prevalence of these benefits suggests that the transition toward a performance-based system will 

continue. The initiation of these new procedures has caused several human performance issues to emerge. 

These issues have been linked to fundamental changes in air traffic operations from both a pilot’s and 

controller’s perspective as well as design challenges that have been placed on aircraft systems that must 

accommodate the changes. Additional human factors issues are associated with proposed new applications 

of RNAV and RNP procedures. To ensure a seamless transition to performance-based navigation, a 
26

collaborative effort between all stakeholders is needed to mitigate issues when they come up in service and 

to anticipate potential issues before introduction of new operations. 

A strong desire to realize the benefits of RNAV and RNP is leading to a dynamic environment 

where issues are observed, brought to the attention of government/industry groups, and addressed in 

targeted studies. There are currently a number of different working groups that are considering issues such 

as those raised in this report. These groups include those sponsored by the FAA, ICAO, and the Joint 

Aviation Authorities (JAA) in Europe. As issues are addressed by these diverse groups, there is a strong 

need for communication and collaboration to ensure consistent findings and to avoid duplication of efforts. 

It would be highly desirable that approaches taken to resolve these issues be globally compatible. 

Coordination between groups would facilitate consensus on issue prioritization and would conserve 

valuable resources. 

Effective worldwide coordination on issue prioritization and investigation is a lofty overall goal. 

Results of this study suggest that even relatively smaller coordination efforts along the way can also yield 

significant benefits. Small groups of technical experts from different fields have developed effective 

solutions to issues that occurred during operational service. Development of instrument procedure design 

criteria based on human performance considerations would likely provide a better link between the 

operational community and the procedure designers. 

 This report and the accompanying Issues List have provided an initial assessment of various human 

factors issues arising from the transition to a performance-based navigation system. Due to the dynamic 

nature of this subject matter, recommended areas for more detailed consideration are expected to evolve 

significantly as new procedures are implemented and greater system capabilities are achieved. It is likely, 

however, that these new issues will continue to have common features with those raised in this report. 

References 

1

RTCA, “Minimum Aviation System Performance Standards: Required Navigation Performance for Area 

Navigation,” RTCA/DO-236B, Washington, DC, 2003. 

2

FAA, “Roadmap for Performance-Based Navigation,” version 1.0, Washington, DC, 2003. 

3

Landrum & Brown, ”Four Corner-Post Plan Environmental Assessment,” FAA, 2001. 

4

Joint Planning and Development Office, “Next Generation Air Transportation System Integrated Plan,” 

Department of Transportation, Washington, DC, 2004. 

5

FAA, “U.S. Terminal and En Route Area Navigation (RNAV) Operations,” AC 90-100, Washington, DC, 

2005. 

6

Barhydt, R. and Adams, C., “Human Factors Considerations for Area Navigation Departure and Arrival 

Procedures,” 25th ICAS, Hamburg, Germany, 2006. 

7

FAA, “Air Traffic Control,” Order 7110.65R, Washington, DC, 2006. 

8

FAA, “Aeronautical Information Manual,” Washington, DC, 2006. 

9

Aeronautical Radio Incorporated, “Navigation System Data Base,” ARINC 424-17, Annapolis, MD, 2004. 

10Ottobre, R., O’Neill, J., and Herndon, A., “Analysis of Advanced Flight Management Systems (FMSs),” 

MITRE, http://www.mitre.org/work/tech_papers/tech_papers_05/05_0894/index.html, 2005. 
27

11FAA, “Acceptance of Data Processes and Associated Navigation Databases,” AC 20-153, Washington, 

DC, 2005. 

12Eurocontrol, “Guidance Material for the Design of Terminal Area Procedures for Area Navigation 

(DME/DME, B-GNSS, Baro-VNAV & RNP-RNAV),” Edition 3.0, 2003. 

13FAA, “Departure Procedure (DP) Program,” Order 8260.46C, Washington, DC, 2005. 

14FAA, “Standard Terminal Arrival Program and Procedures,” Order 7100.9D, Washington, DC, 2003. 

15FAA, “United States Standard for Terminal Instrument Procedures (TERPS),” AC 8260.3B Chg 19, 

Washington, DC, 2002. 

16FAA, “United States Standard for Required Navigation Performance (RNP) Approach Procedures with 

Special Aircraft and Aircrew Authorization Required (SAAAR),” Order 8260.52, Washington, DC, 2005. 

17FAA, “Approval Guidance for RNP Procedures with SAAAR,” AC 90-101, Washington, DC, 2005. 

18FAA, “Criteria for Approval of Category I and Category II Weather Minima for Approach,” AC 120-

29A, Washington, DC, 2002. 

19Aeronautica Civil of the Republic of Colombia, “AA965 Cali Accident Report,” 

http://sunnyday.mit.edu/accidents/calirep.html, Bogota, Columbia, 1996. 

20NTSB, “NTSB Recommendations A96-90 through -106,” http://www.rvs.unibielefeld.de/publications/Incidents/DOCS/ComAndRep/Cali/cali-ntsbrec.html, Washington, DC, 1996. 
 Appendix A: Human Factors Issues List 

Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

1 

Technical Interchange Meeting 

Terry Stubblefield 

FAA Airline 

Procedures 

 High Different operator p

of automation and fprocedures. Some may be needed to eadherence. 

2 

RAT #NAV01.2 /PaRC 

Greg Tennille/ Bill Vaughn 

MITRE/ Continental Airlines 

Airline Procedures 

 Medium Lateral and vertical 

engagement height runway/airport elevoperators/equipmenpath tracking perfoaltitude constraints

guidance on this pr

3 

RNAV Task Force 

Brian Will American Airlines Airline 

Procedures 

ATC Procedures 

 High Some would like to 

information in PDCconcern that informseem like a clearan

4 

PARC Human Factors WG 

Ken Speir Delta Airlines Airline 

Procedures 

ATC Procedures 

Training High Flight crew training 

importance of verifloaded into FMC doperations. Variouhelp ensure accuracmovement time aftepossible verificatioATC. ATL and DFaddressing this issupilots to verify theito ATC workload csolutions are being 

5 ASRS Review Richard Barhydt NASA Airline Procedures Equipment Capabilities Medium Company filed for 

airplane not proper

6 

AC 90-100 FAA Airline 

Procedures 

Equipment Capabilities 

 High Operators must dev

correct GPS operatto alert pilots to losprocedure requiring procedures adequat
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

7 

ASRS Review Richard 

Barhydt 

NASA Airline 

Procedures 

PDC Medium Discrepancies have 

controller understoinformation. 

8 

Checker 5 SID @ KCLT report; 

 FAA Airline 

Procedures 

PDC High RNAV SID filed by 

assigned via pre-deNot detected until rreceived different ccontribute to this ev

9 

ASRS Review Richard 

Barhydt 

NASA Airline 

Procedures 

PDC Flight Crew 

Procedures 

High Important informat

in pre-departure clehave occurred when highlighted and go 

10 

Pilot Deviations Report 

 NASDAC Airline 

Procedures 

PDC Flight Crew 

Procedures 

High Flight crew fails to 

clearance differs froflies wrong procedu

11 

RNAV Task Force 

Dave Nakamura 

Boeing Airline 

Procedures 

RNP Approaches 

 Low A proposed new en

procedure may lead awareness issues. Thow the track is depdisplay. Pilot train

12 

Aircraft OnBoard Navigation Data Integrity: A Serious Problem, 

Transport Canada Database Working Group Paper, 1997

 Transport Canada Airline 

Procedures 

Training High FMS capability var

corporate operationusing FMS and proimplemented. 

13 

Aircraft OnBoard Navigation Data Integrity: A Serious Problem, 

Transport Canada Database Working Group Paper, 1997

 Transport Canada Airline 

Procedures 

Training High Glideslope vs. glide

and training/guidelprevent descent bel
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

14 

Technical Interchange Meeting 

 Southwest 

Airlines 

Airline Procedures 

Training Flight Crew 

Procedures 

Medium Cross aircraft mode

impacts pilot perforto differences in caAircraft changes cadeficiencies in tranequipment functionanother. 

15 

CHECKER 5 report 

 FAA Airline 

Procedures 

Training Flight Crew 

Procedures 

High Familiarity with pro

who fly RNAV prowho don't. Less recconfusion and interand proficiency sesflight crews with le

16 

ASRS Review Richard 

Barhydt 

NASA Airline 

Procedures 

Training FMS (other) High Some flight crews a

FMS or RNAV opedeviation errors and conducting RNAV 

17 

RNAV Task Force 

Ted Demosthenes /Bill McKenzie 

/Boeing Approach 

Naming and Approach Classification 

 High Current approach c

deemed to be inadethat proposed new system should be pto derived minima, size and type and fotechnology). One adistinction between guidance and those Factors complicatesystem include airpprotection, obstacle airspace design, alt

18 

RNAV Task Force 

John Anderson, Kathy Abbott 

Continental Airlines, FAA 

Approach Naming and Approach Classification 

 High Instrument approac

based on the specifthe approach. This proliferation of instApproach names shnavigation perform
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

19 

RNAV Task Force 

Operations Panel 

ICAO Approach 

Naming and Approach Classification 

 High Recommended guid

and landing classifistabilized final apprelated to derived mnumber of approach seamless introductidocumentation, and size and type. 

20 

RNAV Task Force 

John Anderson, Kathy Abbott 

Continental Airlines, FAA 

Approach Naming and Approach Classification 

 High The current approa

(precision/non-precRNAV/RNP. The should be updated. be considered in ligterms in other docuregulations, etc.) 

21 

FAA RNP KSN site 

Terry Stubblefield 

FAA Approach 

Naming and Approach Classification 

Airline Procedures 

 High The current approa

based on equipmenof performance-basnumber of categoritraining and curren

22 

RNAV Task Force 

 Smiths Industries Approach 

Naming and Approach Classification 

FMS (other) High Concerns were rais

FMS approaches as FMS to be certified (expensive). 

23 

PARC Human Factors WG 

PARC Human Factors WG 

PARC Human Factors WG 

Approach Naming and Approach Classification 

FMS Nav Database 

 High No RNP approach 

424. RecommendaRNAV (GPS), RNA

24 

RNAV Task Force 

John Anderson, Kathy Abbott 

Continental Airlines, FAA 

Approach Naming and Approach Classification 

Procedure Design 

 Medium Why are there lowe

precision approachLNAV/VNAV line 

25 

Technical Interchange Meeting 

John Anderson Continental 

Airlines 

Approach Naming and Approach Classification 

RNP Approaches 

 High Confusing to have 

approach to same rX, Y, Z, etc.) distinmay have different Would be better to approach with diffeto different RNP le
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

26 

RNAV Task Force 

Jeff Williams FAA ATC 

Procedures 

 Low "Descend via" has b

pilots and controlleController’s Handb

Aeronautical Inform

"descend via" and "controllers should aSTAR assigned by be given "descend vincludes "expect" arestrictions. These resolve the issue. 

27 

Technical Interchange Meeting 

 Southwest 

Airlines 

ATC Procedures 

 High Ambiguity in phras

SID and STAR proneed more precise p

28 

Pilot Deviations Report 

 NASDAC ATC 

Procedures 

 Low Assigned procedure

instructed to "descemaintain 13000.PIC descended below 1interpreted "descento make the next ha7110.65R7 and the resolve this issue. 

29 

CHECKER 5 report 

 FAA ATC 

Procedures 

 Medium Controller awarene

changes too close tbetween STARs anRecently implementraining is expected 

30 

RNAV Task Force 

FAA FAA ATC 

Procedures 

 Medium FAA moving away 

clearance because pthe information (it clearance). 

31 

ASRS Review NASDAC ATC 

Procedures 

 Medium Frequent changes to 

for landing (LAX, Lhas been implemenawareness of pilot i

route changes. 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

32 

Technical Interchange Meeting 

Tom Petrakis LAS TRACON ATC 

Procedures 

 High No standard phrase

climb clearances on 

follow published redefined in controllecontrollers will use pilots will often clacomply with restricfinal evaluation and 

33 

RAT # AMT01.2 Terry 

Stubblefield 

FAA ATC 

Procedures 

 Medium Non-standard repor

by ATC to compenautomation deficienof SID being perfor

34 

RNAV Task Force 

Jeff Williams FAA ATC 

Procedures 

 Medium Pilots have neglecte

runway change. 71that controller shouon initial contact or assigning a STAR wtransitions.7 If a ru

to 10 NM from runthe controller shoulchanges are expecte

35 

RAT # AMT01.1 Terry 

Stubblefield 

FAA ATC 

Procedures 

 Medium Potential conflict o

Preferred Arrival RDeparture Arrival R(e.g., MAHEM filecleared via the BRU

36 

RAT Issue Paper # TRN02.1.2 

Bruce Tarbert FAA ATC 

Procedures 

Medium Procedures need to 

aircraft on and off Sland. 

37 

RNAV Task Force 

Jeff Williams FAA ATC 

Procedures 

 High ATIS information s

being a clearance (wrunway). Neverthemeans under discusrunway information concerned that ATIto provide this info
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

38 

RNAV Task Force 

Jeff Williams FAA ATC 

Procedures 

 Low Relative to "descen

language provides ccleared to a fix that altitude restriction.7 

the question, “WhaThis change is expeproblem. 

39 

RAT I #PDV01.4/RAT #AMT01.1 

Bruce Tarbert FAA ATC 

Procedures 

 Medium Controllers sometim

of RNAV and non-assigning headingson separation). On operations, controlldetermining the cornon-RNAV aircraft heading/course divaircraft is RNAV; ocontroller ability to is lost and pilot abipotential loss of sep

40 RNAV Task Force John Timmerman ATC Procedures DME/DME Q Routes Medium Will controllers mo

areas where there a

41 

RNAV Task Force 

John Timmerman 

 ATC 

Procedures 

Equipment Capabilities 

Q Routes Medium What are the contro

anticipation? Contpredict profiles of Rpossibly making it RNAV into traffic 

42 

PARC Human Factors WG 

Don Porter FAA ATC 

Procedures 

Flight Crew Procedures 

 High During discussion o

crews with anticipaimprove accuracy oDon expressed connot be put in ATIS pilots might not catairports currently ahaving controllers aprogrammed route. considerations, altediscussed. 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

43 

RAT # AMT02.1 Bruce Tarbert FAA ATC 

Procedures 

Flight Plan Suffix 

 Medium ATC automation au

STARS based on sufiled FP: Pilot unprworkload, communcontroller workload

44 

RAT Issue Paper # TRN02.1.2 

 FAA ATC 

Procedures 

FMS (other) Medium Issuance of interim 

ability to fly the veconstraints. It's eason VNAV during aaddressed this issue

45 

RNAV Task Force 

Jeff Formosa, Al Herndon 

MITRE ATC 

Procedures 

FMS Offsets Low Lost comm and re-j

defined when FMS Path performance mto variance between (intercepting, turn amodels may handle 

46 

PARC Human Factors WG 

Don Porter FAA ATC 

Procedures 

Procedure Design 

 High An issue exists con

way to indicate the an RNAV SID. In much better to a "cincluded a top altituwhere the top altituchart. (Pilots may to look for a top altit's not in a consistelost in the clutter.) 

47 

ASRS Review Richard 

Barhydt 

NASA ATC 

Procedures 

RNAV SID/STAR 

 Medium Traffic conflicts ma

interactions betweeprocedures. 

48 

ASRS Review Richard 

Barhydt 

NASA ATC 

Procedures 

RNAV SID/STAR 

 High Assigned altitude is 

when aircraft is operoute. (Controllers assigned altitude wvectors). 

49 

ASRS Review Richard 

Barhydt 

NASA ATC 

Procedures 

RNAV SID/STAR 

 Medium Different controller

terminology to prov(e.g. "descend via" restrictions").. Cha

clarified this issue. 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

50 

RNAV Task Force 

Steve Ferra FAA Tech Center ATC 

Procedures 

RNAV SID/STAR 

 High Initial studies have 

investigate use of "(comparable to "dethe top altitude be dprovided on all SID

51 

ASRS Review Richard 

Barhydt 

NASA ATC 

Procedures 

RNAV SID/STAR 

 Low Omission of word "

an RNAV SID/STAconfusion. 

52 

RNAV Task Force 

Don Porter FAA ATC 

Procedures 

RNAV SID/STAR 

 High Potential confusion 

associated with "cli"maintain". FAA ievaluation and testi

53 ASRS Review Richard Barhydt NASA ATC Procedures RNAV SID/STAR Medium Some aircraft have 

isn't depicted on the 

54 

RNAV Task Force 

Cathy Adams NASA ATC 

Procedures 

RNAV SID/STAR 

Low Radio calls initially 

SID/STAR proceduclarification of conMITRE study has sair/ground communfacilities. 

55 

Technical Interchange Meeting 

John Anderson Continental 

Airlines 

ATC Procedures 

RNAV SID/STAR 

Flight Crew Procedures 

Medium Clearances that req

off VNAV path (spfrom those publisheoffs) can prevent thdownstream restricVNAV path considsituations may prevaircraft on VNAV? alternatives? ATC that controllers shothe RNAV path. 

56 

Technical Interchange Meeting 

John Anderson Continental 

Airlines 

ATC Procedures 

RNAV SID/STAR 

Flight Crew Procedures 

Medium Last minute runway 

RNAV SID/STAR errors and high crew has its own transitioup discontinuity. Aawareness of this is
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

57 

PARC Human Factors WG 

PARC Human Factors WG 

PARC Human Factors WG 

ATC Procedures 

RNP Approaches 

 High Study determined t

deg track deviationcontrollers to identistandard track errorWhat procedures, trsystems are needed this task? 

58 

Technical Interchange Meeting 

John Anderson Continental 

Airlines 

Chart/Database Commonality 

Medium Navigation databas

differ by two weekcause pilots to use current data if they date. 

59 

RNAV Task Force 

Jim Terpstra Jeppesen Chart/Databa

se Commonality 

 High Charted waypoints 

FMS Nav Database

60 

RNAV Task Force 

Jim Terpstra Jeppesen Chart/Databa

se Commonality 

 High Jeppesen postponin

ARINC 424 coding same-type approach Some FMSs are nochange. In these caaware of the approaselected. Criteria adefault (primary) ap

61 

RNAV Task Force 

Bill Royce Boeing Chart/Databa

se Commonality 

Charting Low Non ILS charts sho

they reflect VNAV navigation database action has been acc

62 

RNAV Task Force 

Jim Terpstra Jeppesen Chart/Databa

se Commonality 

Charting FMS Nav 

Database 

High Some differences e

Legs page for DME distance and latter rname). 

63 

RNAV Task Force 

Jim Terpstra Jeppesen Chart/Databa

se Commonality 

Equipment Capabilities 

 High Pilots should pay e

performance when SID/STARs. 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

64 

RNAV Task Force 

Sam Miller Boeing Chart/Databa

se Commonality 

FMS Nav Database 

Airline Procedures 

Medium Flight crews have r

between track to on published on approdue to different updand approach platebe a problem. Traipilots aware of this 

65 

RNAV Task Force 

 Intl Chart and 

Database Harmonization WG 

Chart/Database Commonality 

FMS Nav Database 

Charting Medium Inconsistency exist

concerning whetheplaced before or aftresults in entry errocommunications. Sacceptable differendatabases in areas ivariation, mileage, Confusion can resuinformation differs database. 

66 

NASA FAA Chart Review 

Richard Barhydt 

NASA Charting Low Apparent inconsiste

between depicted rodescription. This issituation. 

67 

NASA Chart Review 

Richard Barhydt 

NASA Charting Low At least one chart (

has same notes deplocations on chart. 

68 

KCLT-Checker 5 SID;RAT# PDV01.2 

Terry Stubblefield/ Bruce Tarbert 

FAA Charting High Chart clutter causes 

workload and proce

69 

KCLT-Checker 5 SID;RAT# PDV01.2 

Terry Stubblefield/ Bruce Tarbert 

FAA Charting High Chart clutter makes 

or at night difficult

70 

KCLT-Checker 5 SID;RAT# PDV01.2 

Terry Stubblefield/ Bruce Tarbert 

FAA Charting High Collocation of info

examined for both pnotes. 

71 

KCLT-Checker 5 SID;RAT# PDV01.2 

Terry Stubblefield/ Bruce Tarbert 

FAA Charting High Collocation of info

examined: Too mucwith readability. Reoptimize chart real 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

72 

NASA FAA Chart Review 

Richard Barhydt 

NASA Charting Medium Different symbolog

used to indicate the crossing restrictionabove/below altitud"cross at" on othersbe due to a format cchart cycle. 

73 

RNAV Task Force 

Frank Alexander 

Northwest Airlines 

Charting Medium Discussion underw

depiction of some ftype. Would this in

74 RNAV Task Force Jim Terpstra Jeppesen Charting Medium SID/STAR textual 

whether waypoint i

75 

Technical Interchange Meeting 

 Southwest 

Airlines 

Charting Medium Frequencies for VO

the geometry of the charts for verificati

76 

RNAV Task Force 

Bill Vaughn, Kathy Abbott 

Continental Airlines, FAA 

Charting High ‘NA' on LNAV/VN

confusing. Some pmean they can't use VNAV can be used 'NA' refers to 'not aavailable.' A differ

77 

TAOARC Issue Paper 

Kathy Abbott FAA Charting Medium Naming minima lin

same as an operatioconfusion/inappropassumptions. 

78 ASRS Review Cathy Adams ASRS Charting Medium Pilots confused ove

labeling. Would lik

79 

NASA Chart Review 

Richard Barhydt 

NASA Charting High Placing the notes, t

obstacle informatiohigh chart clutter 

80 

Technical Interchange Meeting 

Terry Stubblefield 

FAA Charting High Procedure should n

waypoint: BRUSR MAHEM STAR, e
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

81 

TAOARC Issue Paper 

Terry Stubblefield 

FAA Charting High Minima lines are op

rather than sensor dthe problem is senscapability. In some problem with pilots minima their aircrahandling. 

82 

NASA Chart Review 

Richard Barhydt 

NASA Charting Medium On some charts, the

compelling to distin"at or above" restricto recognize the dif

83 

NASA Chart Review 

Richard Barhydt 

NASA Charting Medium When chart has too 

textual altitude restwaypoint, the inforon the chart. The loreferenced informaspecific and is not sadverse conditions, quickly reference it

84 

RNAV Task Force 

Bill Royce Boeing Charting DME/DME Low "DME/DME RNP 

charts is unnecessacan be demonstrate

85 RNAV Task Force Bill Royce Boeing Charting Equipment Capabilities Medium "ADF Required" no

for operators with e

86 

PARC Human Factors WG 

 PARC Human 

Factors WG 

Charting Flight Crew 

Procedures 

 High Group discussed po

page that would coissues and any specprocedures at a parplaced at beginning particular airport). effective way to disinformation? 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

87 

RNAV Task Force 

RNAV Task Force 

RNAV Task Force 

Charting Flight Crew 

Procedures 

 Medium RNAV Task Force 

minimum temperatinstrument approacbelow this minimum conducted by VNAappropriate tempercompute a straight an approved FMS v

88 

RNAV Task Force 

Bill Royce Boeing Charting Procedure 

Design 

 High Blank minima line 

leads some crews to authorized. 

89 

NASA Chart Review 

Richard Barhydt 

NASA Charting Procedure 

Design 

 High Chart complexity is 

little apparent operdepicts 4 different afor altitude conditiowithin 20 ft of a rou1120 ft) 

90 

KCLT-Checker 5 SID;RAT# PDV01.2 

Terry Stubblefield/ Bruce Tarbert 

FAA Charting Procedure 

Design 

 Low Confusion over con

restrictions based orestrictions listed oOrder 7100.9D disc

91 

PARC Human Factors WG 

Kathy Abbott FAA Charting Procedure 

Design 

 Medium Pilots are sometime

published top altitualtitude restriction restriction at BIKKThe reason for the rthe pilot and the chinconsistent. In thineeded for DME/D

92 

NASA Chart Review 

Richard Barhydt 

NASA Charting Procedure 

Design 

 High Some charts are clu

quickly associate an crossing restriction

93 

RNAV Task Force 

John Anderson, Kathy Abbott 

Continental Airlines, FAA 

Charting Procedure 

Design 

 High Use of 'LNAV/VNA

confusing to pilots already used as aut

94 

RNAV Task Force 

John Anderson, Kathy Abbott 

Continental Airlines, FAA 

Charting Procedure 

Design 

 High Use of 'NA' in LNA

despite charted glidapproach fix (impliflown as depicted). 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

95 

Technical Interchange Meeting 

John Anderson Continental 

Airlines 

Charting RNAV 

SID/STAR 

 Medium Extremely small tex

read. 

96 

RNAV Task Force 

RNAV Task Force 

RNAV Task Force 

Charting RNAV 

SID/STAR 

 Medium Some pilots interpr

north ..." on ATL Rdirection of their ulintended to mean thwording may be ne

97 

Technical Interchange Meeting 

John Anderson Continental 

Airlines 

Charting RNAV 

SID/STAR 

 High There should be a r

related to informatia chart. Informatioincreases clutter anvalue. 

98 

FAA RNP KSN site 

Terry Stubblefield 

FAA Charting RNP 

Approaches 

 High Charting for RNP a

information in ordeconsistent, have miand support planninwill procedure desiincorporate these d

99 

PARC Human Factors WG 

Terry Stubblefield 

FAA Collaboration High Different parts of F

to different procedunecessarily talk to ecommunication can inconsistencies, sucdescription and visu

100 

RNAV Task Force 

Ted Demosthenes 

ICAO Operations Panel 

Collaboration High Numerous organiza

looking into performissues (FAA/JAA, Collaboration is nefindings and to avoPrioritization of issthat most important and to conserve val
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

101 

RAT #NAV 02.4.3 

AFS 410/AIR130 

FAA Equipment 

Capabilities 

 Low Aircraft may be equ

INS or IRS. Operahaving AHRS and sometimes take /F cerroneously. Becauby multiple nav sen(DMEDME,GPS,Vaccuracy is suspectto drift, credit for cafter takeoff, and radegrees course diveOperator must take reporting equipmenprovides guidance i

102 

RNAV Task Force 

Operations Panel 

ICAO Equipment 

Capabilities 

 High Concerns have been 

of continuous descevertical path guidan

103 RNAV Task Force Cathy Adams NASA Equipment Capabilities Medium DME counts down 

leading to potentia

104 RAT # NAV 02.5.1 FAA Equipment Capabilities Medium FMS might not ack

absence of facility's 

105 

RAT # NAV 02.5.1 

 FAA Equipment 

Capabilities 

 Low FMS might not ack

volume limitations degrees. VOR/DMfor FMS. 

106 

Bluecoat Report 28 May 2003 

 Bluecoat Equipment 

Capabilities 

 Medium Map shift noticed o

indicated that grounoccur below 100 kt
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

107 

RAT # NAV 02.4.2 

 FAA Equipment 

Capabilities 

High Different multi-sen

weightings or sourc(DME &/or IRU/S) flight and the navaiDifferences includesearched (several Dof station; monitorifacility status (activ150 degree range ofacilities "off air"-ofor position integritresponsibility to cothrough flight inspeconfirmation of DM

108 RAT # NAV 02.4.2 FAA Equipment Capabilities Low Suffix /E and /F: na

differs among non-

109 

RNAV/SID STAR Implementations 

 FAA Equipment 

Capabilities 

 High Suffix E-G,R boxes 

Need to ID differenmeet TERPS criteri

110 

RNAV Task Force 

Frank Alexander 

Northwest Airlines 

Equipment Capabilities 

 Medium What should be the 

standards for conduoperations? AC 90guidance in this are

111 

Aircraft OnBoard Navigation Data Integrity: A Serious Problem, 

Transport Canada Database Working Group Paper, 1997

 Transport Canada Equipment 

Capabilities 

 Medium Inability of pilots to 

only procedures whagainst raw nav inf

112 

AC 90-100 FAA Equipment 

Capabilities 

Alerting High Aircraft systems m

adequately monitor are some of the impissues? 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

113 

RNAV Task Force 

Bricknell Equipment 

Capabilities 

Alerting DME/DME High Several critical DM

Q routes. Inertial sthrough DME coverelated to how crew DME? What are th

114 

RAT #PDV03.3 FAA Equipment 

Capabilities 

Alerting RNAV 

Approaches 

Medium What are the appro

non-GPS sensor faiapproaches)? 

115 

RAT #NAV02.3 FAA Equipment 

Capabilities 

Alerting RNP 

Approaches 

Medium Alerting limits for R

instrument proceducontainment area bWhen available, RNexceeding manual Rcoded RNP value bdefault RNP value flight), and/or the FRTCA DO-208. Is into alerts to allow 

116 

FAA RNP KSN site 

Terry Stubblefield 

FAA Equipment 

Capabilities 

Alerting RNP 

Approaches 

High Containment alertin

factors principles. include type of alerintensity, flash/stea

117 

RNAV Task Force 

Dave Nakamura 

Boeing Equipment 

Capabilities 

Alerting RNP 

Approaches 

Medium RNP MASPS doesn

threshold for verticstandard be developprovides guidance i

118 

Technical Interchange Meeting 

Richard Barhydt 

NASA Equipment 

Capabilities 

Alerting RNP 

Approaches 

High Some aircraft don’t 

aircraft’s position eare limited to cases and do not account position monitoring sufficient? Are diffor different levels 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

119 

RNAV Action Team AMT01.1 

 FAA Equipment 

Capabilities 

ATC Procedures 

Medium It’s helpful for cont

distinguish between conventional proceprocedure. ControlRNAV/non-RNAV simultaneous operatraffic conflicts. Pochanges include sitdata block to distinRNAV, suggesting toggle RSI ("RNAV when a/c assigned oprocedure by a conscratch pad to displcontents controlled 

120 

PARC Jeff Williams, 

John McGraw 

FAA Equipment 

Capabilities 

Autopilot RNP 

Approaches 

High Uncertain tracking 

during TOGA (takepossibly lead to uneThis problem appeafor older aircraft. 

121 

AC 90-100 FAA Equipment 

Capabilities 

Charting High Pilots must verify t

equipage exists to pAre the equipment understandable? 

122 RAT FAA Equipment Capabilities DME/DME Medium Service volume sat

examined. 

123 

RNAV Task Force 

Bill Vaughn, Kathy Abbott 

Continental Airlines, FAA 

Equipment Capabilities 

DME/DME Alerting High When is a DME/DM

an RNAV SID, STApilots alerted in casthe aircraft revert to 

124 

SAE G10 Cathy Adams NASA Equipment 

Capabilities 

EFB High Discussion on pilot

interpret informatiocompared to use of 

125 

EFB report Divya Chandra VOLPE Equipment 

Capabilities 

EFB High Display of EFB pro

annunciation of coneasily accessible. 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

126 

EFB report Divya Chandra VOLPE Equipment 

Capabilities 

EFB High Visual perception a

instrument proceduaccessing procedursee/understand proc

127 

ASRS Review Richard 

Barhydt 

NASA Equipment 

Capabilities 

EFIS RNAV 

SID/STAR 

High Lack of map displa

workload and possiRNAV departure anShould there be a redisplay? 

128 

Technical Interchange Meeting 

Sam Miller Boeing Equipment 

Capabilities 

EFIS RNP 

Approaches 

Medium B-737 shows misse

distinguish it from approach path turns (Potential issue - do distinguishing apprpath when both are 

129 

Pilot Deviations Report 

 NASDAC Equipment 

Capabilities 

FMS (other) High Aircraft departed D

but did not adequatoff course); pilot saon course. Deviatio

130 

RNAV Task Force 

Operations Panel 

ICAO Equipment 

Capabilities 

FMS (other) High Differences exist in 

Recommendation mflyability should be publication. 

131 

RNAV Task Force 

Mike DeJonge Smiths Industries Equipment 

Capabilities 

FMS (other) High Different FMSs wil

for large angle turnovershoot outbound These differences minconsistencies. 

132 

RNAV Task Force 

Randal Ottobre, John O'Neill, Al Herndon 

MITRE Equipment 

Capabilities 

FMS (other) High FMS design differe

path tracking perfomay be unanticipat

133 

RAT #PDV01.3 FAA Equipment 

Capabilities 

FMS (other) Medium Waypoints: Traject

and fly-over waypoaircraft models (Bo
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

134 

RAeS Flight Operations Group 

Kathy Abbott FAA Equipment 

Capabilities 

FMS (other) Airline 

Procedures 

Medium On Airbus aircraft, 

transition (“Approafix with a programmdefault to the “Appremaining STAR wfix. The resulting por a potential path d

135 

RAeS Flight Operations Group 

Kathy Abbott FAA Equipment 

Capabilities 

FMS (other) Airline 

Procedures 

Medium On Boeing aircraft, 

Legs Page (rather tclearing discontinuunintentional wayp

136 

RAeS Flight Operations Group 

Kathy Abbott FAA Equipment 

Capabilities 

FMS (other) Airline 

Procedures 

Medium On Boeing aircraft, 

not necessarily shoroute. Pilots should verify that all desiractive route. 

137 

PARC Human Factors WG 

Sam Miller Boeing Equipment 

Capabilities 

FMS (other) Airline 

Procedures 

Medium Changing runway o

doesn't automatical(converse occurs - does change it on pcrews should be tra

138 

ASRS Review Richard 

Barhydt 

NASA Equipment 

Capabilities 

FMS (other) Airline 

Procedures 

High Unexpected FMS m

caused altitude devSTARs. This issue training (specific isaircraft). 

139 

PARC Jeff Williams, 

John McGraw 

FAA Equipment 

Capabilities 

FMS (other) ATC 

Procedures 

High Dispersion of flight 

segments leads to uperformance and hi

140 

RNAV Task Force 

Kathy Abbott/ Tom Imrich 

FAA/Boeing Equipment 

Capabilities 

FMS (other) EFIS High FMS interfaces on 

jets do not clearly cand provide error munderstood. 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

141 

PARC Bill Vaughn Continental 

Airlines 

Equipment Capabilities 

FMS (other) RNAV 

Approaches 

High FMS requirements 

RNAV Phase II/III Potential human facminimum RNAV/Rcapabilities, operatidirector, autopilot, operational mitigat

142 

FAA Designee Newsletter 

Terry Stubblefield 

FAA Equipment 

Capabilities 

FMS (other) RNAV 

Approaches 

High VNAV on some GP

for VNAV approacappropriate descent reflect required glidPilots should know 

143 RNAV Task Force unknown source Equipment Capabilities FMS (other) RNAV Approaches High Computed glide pa

below step-down al

144 

PARC Human Factors WG 

 PARC Human 

Factors WG 

Equipment Capabilities 

FMS (other) RNAV 

SID/STAR 

Medium One FMS type disr

after sequencing a wfeature may impact performance in a tu

145 PARC Pedro Rivas Equipment Capabilities FMS (other) RNP Approaches High How should the FM

segments of differe

146 

RAT #NAV02.1 AFS410/AIR130 FAA Equipment Capabilities FMS Nav Database FMS (other) Medium Criteria need to be 

"advanced RNAV" AC 90-100 now proarea.5 

147 

RAT #NAV02.4.1.3 

AFS-410 FAA Equipment 

Capabilities 

FMS Nav Database 

 Inertial Medium QA waypoints desi

may require monitoa potential issue. 

148 

(Source: RAT Issue Paper #NAV 02.4.1; Checker 5 SID at CLT; SIDs at LAS) 

 FAA Equipment 

Capabilities 

Inertial High Impact of loss of ra

Concern over the abminimum navigatioexecute the procedu

149 

PARC Frank 

Alexander 

Northwest Airlines 

Equipment Capabilities 

Inertial Medium Inertial Reference U

requirements to be segments of RNAValignment procedur
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

150 

CHECKER 5 report 

 FAA Equipment 

Capabilities 

Inertial Medium Map shift due to fa

takeoff may cause Sradio source updati

151 

RAT #NAV02.4.1.2 

AIR 130 FAA Equipment 

Capabilities 

Inertial High Not known if an IN

navigation on an Rcoasting state after nav performance exand these nav perfoaligned, leading to misunderstanding ameet performance e

152 

RNAV Task Force 

Barry Miller FAA Equipment 

Capabilities 

RNAV Approaches 

Flight Crew Procedures 

High When conducting a

VNAV, pilots must VNAV capabilities below the step-dowintensive for flight monitoring?) 

153 

RNAV Task Force 

Randal Ottobre, John O'Neill, Al Herndon 

MITRE Equipment 

Capabilities 

RNAV SID/STAR 

 Medium One FMS type doe

constraints. Pilot msolution for some p

154 RNAV Task Force Dave Nakamura Boeing Equipment Capabilities RNP Approaches High Can RNP apply onl

aircraft? 

155 

Technical Interchange Meeting 

Sam Miller Boeing Equipment 

Capabilities 

RNP Approaches 

 Alerting High Navigation perform

trend information ouncertainty (EPU). used by pilots for rperformance. (Potedon't have these scalevel of situation awdegrading situation

156 

RNAV Task Force 

Bill Royce Boeing Flight Crew 

Procedures 

 Medium Flight crew procedu

defined when condoperations with tem

157 

Technical Interchange Meeting 

Brian Townsend 

Air Line Pilots Association 

Flight Crew Procedures 

 Medium On Airbus aircraft, 

the MDCU displayarrivals page. 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

158 

ASRS Review Richard 

Barhydt 

NASA Flight Crew 

Procedures 

Airline Procedures 

RNAV SID/STAR 

High Some waypoint alti

busted while hand-been raised associaprocedures having segments and wayp

159 PARC Jeff Williams, John McGraw FAA Flight Crew Procedures Equipment Capabilities RNP Approaches High Flight crew must ve

available prior to se

160 

Technical Interchange Meeting 

John Anderson Continental 

Airlines 

Flight Crew Procedures 

FMS Nav Database 

RNP Approaches 

High Current software no

enter new RNP valapproach. Would bcoded as part of proautomatically with is currently being dworkload issue for 

161 RNAV Task Force Bill Vaughn, Kathy Abbott Continental Airlines, FAA Flight Crew Procedures Inertial Low When IRU is used 

quick align be used 

162 

MAHEM STAR implementationKPHX 

Terry Stubblefield 

FAA Flight Crew 

Procedures 

Procedure Design 

 Medium Pilot selected wron

have occurred when relatively automateshare initial commois where pilots expearrival clearance bu

163 

MAHEM STAR report 

 FAA Flight Crew 

Procedures 

RNAV Approaches 

 High Occasional difficul

on RNAV approach step down alts. 

164 

MAHEM STAR report 

 FAA Flight Crew 

Procedures 

RNAV Approaches 

Medium Vertical profile: Di

crosschecking comdescent. Descent prpilots to crosscheck raw data. 

165 

RNAV Task Force 

Sam Miller Boeing Flight Crew 

Procedures 

RNP Approaches 

 Medium Some concerns exi

guidance for pilots setting between the high crew workload 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

166 

Technical Interchange Meeting 

 Naverus Flight Crew 

Procedures 

RNP Approaches 

Airline Procedures 

High Flight crews should 

procedures for each LNAV/VNAV engprocedures, checkliPotential issue - hothese recommendatprogram? 

167 

MAHEM RNAV STAR Issues 

 FAA Flight Crew 

Procedures 

Training Medium Several cases repor

different transition. program FMS and 

168 

ASRS Review Richard 

Barhydt 

NASA Flight Crew 

Procedures 

Training Procedure 

Design 

High When running behi

failed to do adequatakeoff. These brieimportant for procemultiple flight pathconstraints. 

169 

RNAV Task Force 

Vincent Chirasello 

FAA Flight Plan 

Suffix 

 High Current flight plan 

describe aircraft caenable controllers tcrew/aircraft capaboperations. A few RNP (but what leveroute? /E and /F aito fly a GPS procedharmonize flight plcapable suffix prevhelping to automate 

170 

PARC Human Factors WG 

Kathy Abbott FAA Flight Plan 

Suffix 

 High Flight plan suffix sh

not a type of equipmnot meet these crite

171 

RAT #NAV02.2 AFS420/ATP501 FAA Flight Plan Suffix High Flight plan suffixes 

better align with aircapability. 

172 

RNAV Task Force 

Tom Imrich Boeing Flight Plan 

Suffix 

 High Flight plan suffixes 

an aircraft's CNS caeasy to understand 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

173 

Pilot Deviations Report 

 NASDAC Flight Plan 

Suffix 

ATC Procedures 

 Medium Foreign carrier assi

flew off course and was not authorized Possible suffix prob

174 

AC 90-100 FAA FAA Flight Plan 

Suffix 

Flight Crew Procedures 

Airline Procedures 

High Pilots are required t

plan suffix. Are thpilots/dispatchers k

175 

RNAV Task Force 

John Timmerman 

 Flight Plan 

Suffix 

Q routes ATC 

Procedures 

Medium How will controller

are equipped to fly equipped aircraft ar

176 

Aircraft OnBoard Navigation Data Integrity: A Serious Problem, 

Transport Canada Database Working Group Paper, 1997

 Transport Canada FMS Nav 

Database 

 Low Courses and bearin

published procedur

177 

Aircraft OnBoard Navigation Data Integrity: A Serious Problem, 

Transport Canada Database Working Group Paper, 1997

 Transport Canada FMS Nav 

Database 

 High Documented proble

Published procedurdatabase; Unpublished procedatabase; Incorrect waypoint Waypoints are addepublished procedurCourses and bearinpublished procedurDuplicate IdentifierInstrument approacdisplayed in the samthe published materSome navaids are n“Hard” Altitudes caobstruction clearan
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

178 

RNAV Task Force 

Jack Befus Smiths Industries FMS Nav 

Database 

 Medium Errors in navigation 

various sources. Thdiscontinuities and Procedures are needchecks in critical aranalysis should be from the previous cprovides a process data integrity durindata to airline-spec

179 

RNAV Task Force 

Jim Terpstra Jeppesen FMS Nav 

Database 

 Low FMS can only store 

fix. Some approachpatterns at the same different approachepatterns be part of a 

180 

Technical Interchange Meeting 

AFS 410 FAA FMS Nav 

Database 

 Medium MAGVAR may be 

collocated airport a

181 

RNAV Task Force 

John Anderson, Kathy Abbott 

Continental Airlines, FAA 

FMS Nav Database 

 Medium Map shifts are often 

navaids. Is this infrecorded in the nav 

182 

Aircraft OnBoard Navigation Data Integrity: A Serious Problem, 

Transport Canada Database Working Group Paper, 1997

 FMS Nav 

Database 

 Medium National source dat

encoded to vendor 424) is subsequentlutilizing in-house sdata to the display. to data integrity coutransformed from ththrough to the FMS 153 now provides a navigation data intefrom source data to 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

183 

CHECKER 5 report 

 FAA FMS Nav 

Database 

 High One FMS/GPS doe

transitions for STA& S) causing databsingle procedure as for each runway tracapture error with pselecting/loading coissue is an example that can lead to con

184 

Aircraft OnBoard Navigation Data Integrity: A Serious Problem, 

Transport Canada Database Working Group Paper, 1997

 Transport Canada FMS Nav 

Database 

 Medium Regular data upgra

functioning. 

185 

RNAV Task Force 

Jim Terpstra Jeppesen FMS Nav 

Database 

Medium Several navaid nam

to flight crew confunames can be confuthe same spelling. uses the same name for multiple fixes o

186 RNAV Task Force Jim Terpstra Jeppesen FMS Nav Database High Some DME stepdo

waypoint names. 

187 

RNAV Task Force 

Jim Terpstra Jeppesen FMS Nav 

Database 

 Medium Some waypoint nam

locations. Determiused can be confus

188 

AFS-410 FAA FMS Nav 

Database 

 Medium Waypoints have be

during arrival to LArunway changed. Toccurred primarily RNAV SID/STAR 

189 

RAT Issue Paper # TRN02.1.2 

 FAA FMS Nav 

Database 

ATC Procedures 

 High After being assigne

runway transition iin the FMS, requirimanually program process leads to hig
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

190 LAX Report FAA FMS Nav Database ATC Procedures High LAX Controller cle

not in FMS. 

191 

Aircraft OnBoard Navigation Data Integrity: A Serious Problem, 

Transport Canada Database Working Group Paper, 1997

 Transport Canada FMS Nav 

Database 

Chart/Database Commonality 

 High Disparity between F

published procedurtransitions, altitude

192 

RAT #NAV01.1 Greg Tennille MITRE FMS Nav 

Database 

Equipment Capabilities 

Procedure Design 

High If FMS or GPS doe

leg type defined in provider may use awhich could lead to Affects software upof system to perforaccurately. 

193 

Checker 5 Report FAA FMS Nav 

Database 

Procedure Design 

 Medium Canned database fo

routings by locationTERPS would cons

194 

RNAV Task Force 

Randal Ottobre, John O'Neill, Al Herndon 

MITRE FMS Nav 

Database 

Procedure Design 

 High Database supplier m

designer's intent reschecked for terrain 

195 

ASRS Review NASA FMS Nav 

Database 

Procedure Design 

 High Descent gradient: F

flight path as depicmay cause computedown altitudes. 

196 

ARINC 424 Cathy Adams NASA FMS Nav 

Database 

Procedure Design 

 High FMS navigation da

all path terminators workaround strategconsequences (such 

197 

RNAV Task Force 

Jim Terpstra Jeppesen FMS Nav 

Database 

Procedure Design 

Medium Some conditional f

into FMS (e.g. misswaypoint or altitudConditional wayporunway are another 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

198 

ASRS Review Richard 

Barhydt 

NASA NOTAMs Medium Flight crew failed t

to FMS data error. extract important indue to a large numbunimportant items. additional consider

199 

PARC Randy 

Kenagy, Ken Speir 

AOPA, Delta Airlines 

NOTAMs Medium NOTAM improvem

too vague) when Din civilian airspace

200 

AC 90-100 FAA NOTAMs Flight Crew 

Procedures 

Equipment Capabilities 

Medium Pilots must confirm 

infrastructure durinDoes adequate infothat task? Does it aworkload? 

201 

STAR Order 7100.9D 

 FAA Procedure 

Design 

 Medium Excessive intercept 

interception probleintercept to a courscomfortable. 

202 

Checker 5 Report FAA Procedure 

Design 

 Medium Checker 5 procedur

of vectors into and analysis done to dewhile flying series operations converteThe FAA has develfor implementing a addresses flyability effects of this issue

203 

CHECKER 5 report 

 FAA Procedure 

Design 

 High Determination mad

has excessive at or restrictions in short 

204 

RNAV Task Force 

 Obstacle 

Clearance Panel WG 

Procedure Design 

 High How should minim

approaches to non-
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

205 

Aircraft OnBoard Navigation Data Integrity: A Serious Problem, 

Transport Canada Database Working Group Paper, 1997

 Transport Canada Procedure 

Design 

 High Human performanc

reduced processing tracking) are attribudesign features and 18-step process for procedure should hcomprehensive and guidelines that concperformance still ap

206 

AFS-410, operational exp, implementation meeting notes; TIMs 

Terry Stubblefield 

FAA Procedure 

Design 

 High Impact of design on

requirements. 

207 

AFS-410, operational exp, implementation meeting notes; TIMs 

Terry Stubblefield 

FAA Procedure 

Design 

 High Impact of design on 

18-step process for procedure should hcomprehensive and guidelines that concperformance still ap

208 

CHECKER 5 report 

 FAA Procedure 

Design 

 High Reported that Chec

fit/flow well with sdeparture profiles f10,000 feet, througor through approac(aircraft configuratcockpit workflows 18-step process for procedure should hcomprehensive and guidelines that concperformance still ap
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

209 

RNAV Task Force 

Operations Panel 

ICAO Procedure 

Design 

 High Is it appropriate to 

gradients and other purposes other than abatement, ATC floConcerns have been flight crew workloanon-critical reasonsensure that procedubalance between aineeds. The 18-step new procedure shouA comprehensive aguidelines that concperformance still ap

210 

Technical Interchange Meeting 

 Southwest 

Airlines 

Procedure Design 

 Medium Pilots dislike minut

forth on STARs anare difficult to see/eFMS capabilities ar

211 

ASRS Review Richard 

Barhydt 

NASA Procedure 

Design 

 Medium Some RNAV wayp

pronounce and couspoken over radio (TEYYI, etc.) FAA this issue. 

212 

ASRS Review Richard 

Barhydt 

NASA Procedure 

Design 

 Medium Two similar soundi

has led to pilot conover the radio (e.g. 

213 

RAT #PDV01.3 FAA Procedure 

Design 

 High Waypoints: Flyove

how and when they procedure design. 

214 

CHECKER 5 report 

 FAA Procedure 

Design 

 High Waypoints: proxim

guidelines should afor effects on proceworkload, and abili

215 

ASRS Review Cathy Adams NASA Procedure 

Design 

ATC Procedures 

 High Altitude and Speed 

design and ATC mmight conflict. 

216 

ASRS Review Cathy Adams NASA Procedure 

Design 

ATC Procedures 

 Medium Approach too close 

Area (MOA) causerestrictions contrary 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

217 

RNAV Task Force 

 NASA Procedure 

Design 

ATC Procedures 

 High High intercept angl

may increase worklpilots ability to tracoff RNAV and aske

218 

ASRS Review Richard 

Barhydt 

NASA Procedure 

Design 

ATC Procedures 

Flight Crew Procedures 

High Pilot deviated aroun

came in too high on procedures sufficienecessary tactical davoidance? 

219 

CHECKER 5 report 

 FAA Procedure 

Design 

Charting Medium Charted "expect alt

have potential to ininduce unexpected 

220 

RNAV Task Force 

Bruce Tarbert FAA Procedure 

Design 

DME/DME Q Routes High DME gaps exist in 

Should procedures DME/DME) or shoMEAs? How shouwhen it’s dependen

221 

PARC Bill Vaughn Continental 

Airlines 

Procedure Design 

Equipment Capabilities 

 High Can parallel RNAV

conducted simultanconcerning navigatrepeatability. 

222 

RNAV Task Force 

 NASA Procedure 

Design 

Equipment Capabilities 

 Medium Intercept Angles: E

acceptable angle of accept more than 3

223 

Checker 5 SID at CLT; SIDs at LAS 

 FAA Procedure 

Design 

Equipment Capabilities 

High Problems reported 

proximity to departradio updating occuAggressive bank an

224 

PARC Operations 

Panel 

ICAO Procedure 

Design 

Flight Crew Procedures 

 High Current nav proced

often lead to high cmay be complex andelay configuration radius requirementsconcerns. High pitto see VFR traffic ukept slow (near ma

225 

RNAV Task Force 

Obstacle Clearance Panel WG 

Obstacle Clearance Panel WG 

Procedure Design 

FMS (other) High Should there be a m

final approach fix? different RNAV sy
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

226 

RNAV Task Force 

Thomas Schneider 

FAA Procedure 

Design 

RNAV Approaches 

 High What are the criteri

it's appropriate to uapproach) as a DA Should the DA minMDA? 

227 

RNAV Task Force 

Operations Panel 

ICAO Procedure 

Design 

RNAV Approaches 

 High What are the obstac

crew issues pertainDA? 

228 

RNAV Task Force 

Operations Panel 

ICAO Procedure 

Design 

RNAV Approaches 

Airline Procedures 

Low Although continuou

are generally considdowns, the latter msome cases (e.g. icirunway requires greguidelines exist for be trained accordin

229 

ASRS Review Richard 

Barhydt 

NASA Procedure 

Design 

RNAV SID/STAR 

 High RNAV SID/STAR 

waypoint on anotheconfusion and pilotwrong procedure. 

230 

RNAV Task Force 

RNAV Task Force 

RNAV Task Force 

Procedure Design 

RNAV SID/STAR 

 High Several procedure d

considered when coRNAV departures: initial fix, minimum course change for i

231 

RNAV Task Force 

Bruce Tarbert FAA Procedure 

Design 

RNAV SID/STAR 

 High Some procedure mo

tracking performanexample): speed cobank angle limitatiochanges. Do proceexist for determininprocedure features performance? Are these techniques shhow they should be attributes that loweperformance been i

232 RNAV Task Force Bruce Tarbert FAA Procedure Design RNAV SID/STAR High Some waypoint and 

have led to unantic
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

233 

PARC Human Factors WG 

PARC Human Factors WG 

PARC Human Factors WG 

Procedure Design 

RNAV SID/STAR 

 Medium Speed restriction at 

key mitigating factoanticipation errors. 

234 

RNAV Task Force 

Ken Speir, Dennis Zondervan 

Delta Airlines, ATL TRACON 

Procedure Design 

RNAV SID/STAR 

 Medium VA to CF and VI to 

for ATL SID/STARover the other? 

235 CHECKER 5 

report 

 FAA Procedure 

Design 

RNAV SID/STAR 

 Medium Too many transitio

confusion in some 

236 

AFS-410, operational exp, implementation meeting notes; TIMs 

Terry Stubblefield 

FAA Procedure 

Design 

RNAV SID/STAR 

 High Occasional impact 

interfering with checockpit tasks such aand speed/altitude rprocess for developshould help address comprehensive and guidelines that concperformance still ap

237 

Technical Interchange Meeting 

Terry Stubblefield 

FAA Procedure 

Design 

RNAV SID/STAR 

 High Potential for captur

procedures share mor waypoints. 

238 

RNAV Task Force 

unknown source 

 Procedure 

Design 

RNAV SID/STAR 

 Medium RNAV SIDs and co

may conflict with eto come in close pr

239 

RNAV Task Force 

 FAA Procedure 

Design 

RNAV SID/STAR 

 High The determination 

or fly by waypoint waypoint is to the rbe carefully analyzminimized. 

240 

Technical Interchange Meeting 

John Anderson Continental 

Airlines 

Procedure Design 

RNAV SID/STAR 

 High Tight turns in proce

problems when aircrestrictions may be problem. 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

241 

RNAV Task Force 

Bruce Tarbert FAA Procedure 

Design 

RNAV SID/STAR 

Airline Procedures 

High What is the appropr

the first waypoint aUnpredictable flighLNAV is engaged awaypoint exists 0.5 end of runway. 

242 

PARC Human Factors WG 

PARC Human Factors WG 

PARC Human Factors WG 

Procedure Design 

RNAV SID/STAR 

ATC Procedures 

High Some RNAV proce

radar vectors off ruhas initial waypoindesign aspect may transition plans whintroduced graduallthe runway. 

243 

RNAV Task Force 

Frank Alexander 

Northwest Airlines 

Procedure Design 

RNAV SID/STAR 

DME/DME High What should be the 

initial fix from depenable adequate DM

244 

RNAV Task Force 

Bruce Tarbert FAA Procedure 

Design 

RNAV SID/STAR 

FMS Nav Database 

Medium Recommends imple

intercept path termiSID/STARs. Headcurrently used as a ramifications of thi

245 

ASRS Review Richard 

Barhydt 

NASA Procedure 

Design 

RNAV SID/STAR 

Training High Unconventional "at 

RNAV SID is occadoesn't meet flight for altitude crossing Awareness training 

246 PARC Human Factors WG PARC Human Factors WG Procedure Design RNP Approaches High How much of a pre

needed for RF legs 

247 PARC Jeff Williams, John McGraw FAA Procedure Design RNP Approaches High How much of a stra

before and after dec

248 

Technical Interchange Meeting 

 Naverus Procedure 

Design 

RNP Approaches 

 High Limiting procedure 

ARINC leg types ctracking performanpredictable than fly

249 

Technical Interchange Meeting 

 Naverus Procedure 

Design 

RNP Approaches 

 Medium Multiple CF legs ca

waypoint (FMS contrue course). These disconcerting to the legs eliminates this 
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

250 

Technical Interchange Meeting 

 Naverus Procedure 

Design 

RNP Approaches 

 High Naverus believes th

RNP procedures wias tailored proceduShould there be comconcerning when a suitable for a public 

251 

Technical Interchange Meeting 

 Naverus Procedure 

Design 

RNP Approaches 

 High Naverus-designed R

straight segment beprotects against the when initiating a gocauses older aircrafthere other considethe minimum altitu

252 PARC Pedro Rivas Procedure Design RNP Approaches Medium What airspeeds sho

based on each class 

253 

PARC Pedro Rivas Procedure 

Design 

RNP Approaches 

 High For a RNP approac

altitude in which thestablished on the ecenterline? 

254 

PARC Jeff Williams, 

John McGraw 

FAA Procedure 

Design 

RNP Approaches 

 High What should be the 

which all segments says 500 ft HAT). 

255 

Technical Interchange Meeting 

 Naverus Procedure 

Design 

RNP Approaches 

Airline Procedures 

High Naverus considers 

procedures, aircraft serviced when deveapproaches. How sbe generalized wheapproaches? Public accommodate multprocedures, and FM
Issue 

(No) Source (No) Contact Organization Category Keyword #1 Keyword #2 

Priority H, M, L S

256 

Technical Interchange Meeting 

 Naverus Procedure 

Design 

RNP Approaches 

Airline Procedures 

High With RNP, it may b

definition of a "stabpotential revised destabilized approach vertical trajectory tsystem and be predstabilized approach final landing gear aWill airlines and rethis or another propsimulator studies ne

257 

PARC Human Factors WG 

Kathy Abbott FAA Procedure 

Design 

RNP Approaches 

RNAV Approaches 

High Should identify vis

approaches where D(runway identificatcoming out of clouetc.) 

258 

RNAV Task Force 

Obstacle Clearance Panel WG 

Obstacle Clearance Panel WG 

Procedure Design 

RNP Approaches 

RNAV Approaches 

High What is the approp

approach segment? 

259 PARC Human Factors WG PARC Human Factors WG PARC Human Factors WG Procedure Design RPAT Flight Crew Procedures High Will RNP aircraft b

identify ILS traffic 

 Issues Summary:  High 144  Medium 96  Low 19  Total 259 
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

2. REPORT TYPE 

Technical Memorandum

 4. TITLE AND SUBTITLE

Human Factors Considerations for Performance-Based Navigation

5a. CONTRACT NUMBER

 6. AUTHOR(S)

Barhydt, Richard; and Adams, Catherine A.

 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

NASA Langley Research Center

Hampton, VA 23681-2199

 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

 8. PERFORMING ORGANIZATION

 REPORT NUMBER

L-19296

10. SPONSOR/MONITOR'S ACRONYM(S)

NASA

13. SUPPLEMENTARY NOTES

An electronic version can be found at http://ntrs.nasa.gov

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified - Unlimited

Subject Category 03

Availability: NASA CASI (301) 621-0390

19a. NAME OF RESPONSIBLE PERSON

STI Help Desk (email: help@sti.nasa.gov)

14. ABSTRACT

A transition toward a performance-based navigation system is currently underway in both the United States and around the

world. Performance-based navigation incorporates Area Navigation (RNAV) and Required Navigation Performance (RNP)

procedures that do not rely on the location of ground-based navigation aids. These procedures offer significant benefits to

both operators and air traffic managers. Under sponsorship from the Federal Aviation Administration (FAA), the National

Aeronautics and Space Administration (NASA) has undertaken a project to document human factors issues that have emerged

during RNAV and RNP operations and propose areas for further consideration. Issues were found to include aspects of air

traffic control and airline procedures, aircraft systems, and procedure design. Major findings suggest the need for human

factors-specific instrument procedure design guidelines. Ongoing industry and government activities to address air-ground

communication terminology, procedure design improvements, and chart-database commonality are strongly encouraged.

15. SUBJECT TERMS

Human factors; RNAV; RNP; Instrument procedure design; Flight operations

18. NUMBER

 OF 

 PAGES

70

19b. TELEPHONE NUMBER (Include area code)

(301) 621-0390

a. REPORT

U

c. THIS PAGE

U

b. ABSTRACT

U

17. LIMITATION OF 

 ABSTRACT

UU

Prescribed by ANSI Std. Z39.18

Standard Form 298 (Rev. 8-98)

3. DATES COVERED (From - To)

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

11. SPONSOR/MONITOR'S REPORT

 NUMBER(S)

NASA/TM-2006-214531

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PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

1. REPORT DATE (DD-MM-YYYY)

01- 12 - 2006