NASA/TP-2001-210665

Simulator Evaluation of Airborne

Information for Lateral Spacing (AILS)

Concept

Terence S. Abbott and Dawn M. Elliott

Langley Research Center, Hampton, Virginia

March 2001
The NASA STI Program Office . . . in Profile

Since its founding, NASA has been dedicated

to the advancement of aeronautics and space

science. The NASA Scientific and Technical

Information (STI) Program Office plays a key

part in helping NASA maintain this

important role.

The NASA STI Program Office is operated by

Langley Research Center, the lead center for

NASA’s scientific and technical information.

The NASA STI Program Office provides

access to the NASA STI Database, the

largest collection of aeronautical and space

science STI in the world. The Program Office

is also NASA’s institutional mechanism for

disseminating the results of its research and

development activities. These results are

published by NASA in the NASA STI Report

Series, which includes the following report

types:

• TECHNICAL PUBLICATION. Reports of

completed research or a major significant

phase of research that present the results

of NASA programs and include extensive

data or theoretical analysis. Includes

compilations of significant scientific and

technical data and information deemed

to be of continuing reference value. NASA

counterpart of peer-reviewed formal

professional papers, but having less

stringent limitations on manuscript

length and extent of graphic

presentations.

• TECHNICAL MEMORANDUM.

Scientific and technical findings that are

preliminary or of specialized interest,

e.g., quick release reports, working

papers, and bibliographies that contain

minimal annotation. Does not contain

extensive analysis.

• CONTRACTOR REPORT. Scientific and

technical findings by NASA-sponsored

contractors and grantees.

• CONFERENCE PUBLICATION.

Collected papers from scientific and

technical conferences, symposia,

seminars, or other meetings sponsored or

co-sponsored by NASA.

• SPECIAL PUBLICATION. Scientific,

technical, or historical information from

NASA programs, projects, and missions,

often concerned with subjects having

substantial public interest.

• TECHNICAL TRANSLATION. Englishlanguage translations of foreign scientific

and technical material pertinent to

NASA’s mission.

Specialized services that complement the

STI Program Office’s diverse offerings include

creating custom thesauri, building customized

databases, organizing and publishing

research results . . . even providing videos.

For more information about the NASA STI

Program Office, see the following:

• Access the NASA STI Program Home

Page at http://www.sti.nasa.gov

• Email your question via the Internet to

help@sti.nasa.gov

• Fax your question to the NASA STI

Help Desk at (301) 621-0134

• Telephone the NASA STI Help Desk at

(301) 621-0390

• Write to:

NASA STI Help Desk

NASA Center for AeroSpace Information

7121 Standard Drive

Hanover, MD 21076-1320
National Aeronautics and

Space Administration

Langley Research Center

Hampton, Virginia 23681-2199

NASA/TP-2001-210665

Simulator Evaluation of Airborne

Information for Lateral Spacing (AILS)

Concept

Terence S. Abbott and Dawn M. Elliott

Langley Research Center, Hampton, Virginia

March 2001
Available from:

NASA Center for AeroSpace Information (CASI) National Technical Information Service (NTIS)

7121 Standard Drive 5285 Port Royal Road

Hanover, MD 21076-1320 Springfield, VA 22161-2171

(301) 621-0390 (703) 605-6000

Acknowledgments

The authors gratefully acknowledge the significant contributions of the many members of the research and development team, both Government and Industry, that were required to implement this concept and conduct the simulation

test. With respect and gratitude we offer tribute to the pioneers of the AILS concept, Leonard Credeur, Charlie

Scanlon, Marvin Waller, Gary Lohr, and Bill Capron. Also deserving of credit are the other members of the Langley

AILS development team, R. Brad Perry, Phil Brown, Laura Rine, and Donner Grigsby, as well as the contractor

counterparts, from Lockheed Martin Engineering & Sciences Corporation, Jake Barry, Dan Burdette, and Frank

McGee; retired United Airline Captains, William Gifford and Dave Simmon; and from Adsystech, Inc., Thomas

Doyle. Much appreciation is also extended to Honeywell, Inc., specifically, Bill Corwin, Dave Maahs, Jarold Weiser,

Paul Samanant, Mike Jackson, Scott Snyder, and Christine Haissig, for taking an interest in the AILS concept and

working to make this research a success. Many other persons whose names are not mentioned here have contributed

significantly, and the authors express their sincerest thanks. The authors are only reporting the results of this study; the

research, development, and implementation team members are what made this report possible.
iii

Contents

List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

List of Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Concept Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Reducing the Intrusion Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Navigation Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Lateral Path Boundary Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Pilot Alerting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Guarding Against the Intruder. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

General Operational and Pilot Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Loss of AILS Capability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Potential Loss of Lateral Separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Emergency Escape Maneuver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Hardware Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Alerting Algorithm Description and Associated Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Localizer Alerts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Path Alerts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Traffic Alerts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Alert Priority and Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Evaluation Design and Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Test Subjects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Independent Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Intruder Geometry and Relative Speeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Aircraft Control Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Intruder Runway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Pilot Run Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Aircraft Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

TCAS Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Traffic Generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Air Traffic Control Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Pilot Training and Evaluation Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Initial Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Quantitative Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Miss-Distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Pilot Reaction Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
iv

Qualitative Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Scaled, Discrete Questions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Free-Response Questions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Summary of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Appendix A—Classroom Briefing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Appendix B—Flight Manual Bulletin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Appendix C—Simulator Briefing and Training Script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Appendix D—Quantitative Data Analysis Details. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Appendix E—AILS Pilot Questionnaire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
v

List of Tables

Table 1. AILS Alerting Table and Alerting Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Table 2. Run Matrix for Pilot 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Table 3. Slant-Range Miss-Distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Table 4. Pilot Reaction Times (sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Table 5. Summary Statistics for Responses to Questionnaire Questions 1

Through 8, 11, and 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table 6. Summary Statistics for Responses to Questions 13–16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

List of Figures

Figure 1. Parallel ILS approaches to runways spaced 2500 ft apart. Drawing not to scale . . . . . . . . . . 20

Figure 2. Example of constant-width approach design to two closely spaced

parallel runways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 3. Example of nonoverlapping, ILS-lookalike approaches using single 4° offset . . . . . . . . . . . 20

Figure 4. Example of nonoverlapping, ILS-lookalike approaches using dual 2° offsets . . . . . . . . . . . . 20

Figure 5. Example of 2° offset approach to right parallel runway (offset is to right side). . . . . . . . . . . 21

Figure 6. Example of AILS instrument approach chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 7. Candidate hardware architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 8. Example of localizer advisory alert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 9. Determining at-fault collision potential of ownship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 10. Example of PATH caution alert on EADI and ND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 11. Example of PATH warning alert on EADI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 12. Determining the intrusion threat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 13. Example of TRAFFIC caution alert on EADI and ND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Figure 14. Example of TRAFFIC warning alert on ND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Figure 15. Langley Integration Flight Deck layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Figure 16. Center console layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 17. Langley Integration Flight Deck Simulation and Langley Research System

Integration Laboratory layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 18. Slant-range miss-distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 19. Pilot reaction time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 20. Distribution of responses to question 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 21. Distribution of responses to question 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
vii

Nomenclature

A/C aircraft

ACAR automatic communications and recording system

ADS-B Automatic Dependent Surveillance Broadcast

AFE above field elevation

AGL above ground level

AILS Airborne Information for Lateral Spacing

A/P autopilot

APP approach

ARINC Aeronautical Radio Incorporated

ATC Air Traffic Control

C Captain

CASPER Closely Spaced Parallel Approaches

CDI Course Deviation Indicator

CDU control display unit

CRT cathode-ray tube

CWS control wheel steering

DGPS differential GPS

DH decision height

DME distance-measuring equipment

EADI Electronic Attitude Director Indicator

EEM emergency escape maneuver

evader properly maneuvering aircraft being threatened by another aircraft with collision

F f-factor

FAA Federal Aviation Administration
viii

FAC final approach course

FAF final approach fix

F/D flight director

FMS Flight Management System

F/O First Officer

GA go-around

GPS global positioning system

HSI horizontal situation indicator

IFD Langley Integration Flight Deck

IFR instrument flight rules

ILS instrument landing system

intruder improperly maneuvering aircraft that produces collision risk to another aircraft

KIAS knots indicated airspeed

MANOVA multivariate analysis of variance

MAP missed approach point

MCP mode control panel

MD miss distance

MIC microphone

N number

NASA National Aeronautics and Space Administration

ND navigation display

NM nautical mile

NMAC near midair collision, where aircraft is within 500 ft of another aircraft

ownship from a flight crew’s perspective, aircraft that they are flying

P probability
ix

PF pilot flying

PFD primary flight display

PNF pilot not flying

PRM Precision Runway Monitor

RA resolution advisory

RSIL Langley Research System Integration Laboratory

RTO rejected takeoff

SOP standard operating procedures

T value from t-test

TA traffic advisory

TCAS Traffic Alert and Collision Avoidance System

TO takeoff

VFR visual flight rules

VNAV vertical navigation
Abstract

The Airborne Information for Lateral Spacing (AILS) concept is

designed to support independent parallel approach operations to runways spaced as close as 2500 ft. This report describes the AILS operational concept and the results of a ground-based flight simulation

experiment of one implementation of this concept. The focus of this

simulation experiment was to evaluate pilot performance, pilot acceptability, and minimum miss-distances for the rare situation in which an

aircraft on one approach intrudes into the path of an aircraft on the

other approach. Results from this study showed that the design-goal

mean miss-distance of 1200 ft to potential collision situations was surpassed with an actual mean miss-distance of 2236 ft. Pilot reaction

times to the alerting system, which was an operational concern, averaged 1.11 sec, well below the design-goal reaction time of 2.0 sec.

These quantitative results and pilot subjective data showed that the

AILS concept is reasonable from an operational standpoint.

Introduction

In recent years, airport runway construction within the United States has not been able to keep pace

with the rise in traffic growth; this has resulted in an increase in both the number and duration of flight

delays. In addition, many U.S. airports depend on parallel runway operations to meet the growing

demand for day-to-day operations. In the current airspace system, poor weather conditions reduce the

capacity of closely spaced parallel runway operations. These capacity losses can result in landing delays

causing inconveniences to the traveling public, interruptions in commerce, and increased operating cost

to the airlines. The Federal Aviation Administration (FAA) has addressed this reduced capacity problem

for closely spaced parallel runways in its Precision Runway Monitor (PRM) Program (ref. 1). With

ground-based radar technology consisting primarily of high update rate, more accurate radar, and higher

resolution displays for Air Traffic Control (ATC) stations, PRM has certified capabilities to operate

independent parallel approaches to runway separations as close as 3400 ft.

To further exploit independent parallel runway operations at airports with runway spacing below

4300 ft, the National Aeronautics and Space Administration has developed a flight deck centered concept that may allow operations below the current PRM runway separation minima. This new concept is

called Airborne Information for Lateral Spacing (AILS) and is designed to support independent parallel

approach operations to runways spaced as close as 2500 ft. This report describes the current AILS operational concept and the results of a ground-based flight simulation experiment of one implementation of

this concept. The focus of this simulation experiment was to evaluate pilot performance, pilot acceptability, and minimum miss-distances for the rare situation in which an aircraft on one approach intrudes

into the path of an aircraft on the other approach.

This effort was conducted under the Terminal Area Productivity Program of the NASA Aviation

System Capacity Project. Avionics hardware development and integration to support the AILS concept

was provided by Honeywell, Inc. under a cooperative agreement.
2

Concept Overview

The Airborne Information for Lateral Spacing (AILS) concept is an operational, procedures-based

technique, along with appropriate supporting technologies, for conducting independent, simultaneous

approaches to closely spaced parallel runways. For suitably equipped aircraft with eligible crews, AILS

is very similar to today’s typical instrument approach operations. AILS only becomes truly obvious to

the flight crew when an extremely unusual event occurs: one aircraft flies off path and threatens the

safety of another.

The AILS concept focuses on two aspects of the closely spaced parallel approach problem. First,

approach paths must be designed and flown such that the possibility of one aircraft on one approach

interfering with another aircraft on the other approach is remote. Second, if this remote event does

occur, a means must be provided that will allow the nonoffending aircraft to safely avoid the intruding

aircraft. How AILS accommodates both these operational aspects of the closely spaced parallel

approach problem is described in the following sections.

Reducing the Intrusion Risk

The primary means for safely conducting simultaneous, independent instrument approaches to

closely spaced parallel runways is through approach design and flight operations that would reduce the

possibility of one aircraft intruding into the approach path of another. To accomplish this, the AILS concept requires a highly accurate navigation source, an approach path design that minimizes the potential

for intrusions, and pilot alerting for situations that would generate a collision risk.

Navigation Source

From a navigation sensor standpoint, the AILS concept assumes the use of differential global posititioning system (DGPS) or a navigation source with an equivalent level of accuracy and precision. The

use of a standard instrument landing system (ILS) was not considered to be adequate due to course

“bends” and other navigation anomalies that are not unusual to a typical ILS installation.

Lateral Path Boundary Design

From the approach design standpoint, straight-in, parallel approaches using standard ILS design

were considered to be unacceptable for an AILS operation due to lateral path boundary overlap. (See

fig. 1.) For a typical arrangement with runways spaced 3400 ft apart, lateral path boundary overlap

would occur approximately 6 nmi from the runway thresholds. For a 2500-ft runway separation, the

overlap would occur approximately 4 nmi from the thresholds. The problem with even the 3400 ft separation is that at 6 nmi, two aircraft could be operating legally within their respective approach paths and

yet pose a collision threat to each other. One means to alleviate this problem would be to use nonangular

lateral path boundaries. Previous AILS studies (ref. 2) used a constant-width path along the portion of

the approach where the parallel approach aircraft could be at similar altitudes. In the example shown in

figure 2, a minimum 1000 ft of vertical separation would be maintained beyond 10 nmi from the runway. At this distance, a 2000-ft path width would be used to accommodate normal intercept errors while

acquiring the final approach course. Within 10 nmi of the runway, the vertical profiles for each

approach were the same.

For the near future, two significant issues significantly diminish the potential for using the constantwidth approach paths described previously. First, current production DGPS-based approach systems
3

mimic, from an approach design standpoint, conventional ILS approaches. In simple terms, the processing and signal output from the airborne DGPS hardware appears as a “perfect” ILS to the other systems

on the aircraft and the approach is flown much like a conventional ILS. This type of DGPS implementation is known as an ILS-lookalike. The second issue with constant-width approach paths is that many

older generation autopilots may not be able to track these paths without unacceptable lateral tracking

oscillations.

One alternative that would allow for the use of DGPS ILS-lookalike approaches while eliminating

the lateral path boundary overlap is an offset approach path. In this alternative, one or both of the lateral

paths to the parallel runways would be angularly offset or slewed such that the inner path boundaries

between the two approach paths would be parallel. (See figs. 3 and 4.) For this study, it was determined

that the more challenging option of this alternative would be to slew both approaches 2° away from the

opposite approach. The lateral path design for a right-side runway is shown in figure 5. The left-side

runway is a mirror image of this figure, with the offset to the left. There are two operational disadvantages to offset approaches. First, there is a penalty in the decision height. In the design used for this

study, this penalty was 50 ft, resulting in a 250-ft decision height for a nominally configured runway.

The second problem is that the offset approach requires the pilot to manually turn the aircraft onto the

runway centerline during a critical phase of flight, thereby adding to pilot workload. Although neither of

these disadvantages is overwhelming, they can add to the operational “cost” of the AILS concept.

Pilot Alerting

The AILS concept uses two distinctly different classes of alerts for aircraft whose poor approach

path tracking performance may produce a collision risk. The first class is a simple set of lateral path

error alerts. That is, alerts are generated when an aircraft deviates farther than one half the width of the

lateral boundary and also when the lateral boundary has been exceeded. The second class of navigation

alerts is the potential-collision alerts that are generated when the maneuvering of your aircraft places

another aircraft at risk. A detailed explanation of these alerts is provided in the section “Alerting

Algorithm Description and Associated Displays.”

Guarding Against the Intruder

In the remote event that an aircraft on the parallel approach turns off its path and threatens an aircraft on the other approach with a potential collision situation, alerts are provided to the threatened

aircraft.

General Operational and Pilot Procedures

As stated previously, an AILS approach would be very similar to today’s typical ILS approach

operation. Like today, flight crews would conduct an approach briefing using an instrument approach

chart (fig. 6), although this chart would now include the emergency breakout maneuver required for this

procedure. (The emergency breakout maneuver is defined as an emergency escape maneuver (EEM)

and is described in the section “Emergency Escape Maneuver.”) Aircraft would either be radar vectored

or use a charted route to become established on the final approach course with the flight crews selecting

the relevant approach either through the Flight Management System (FMS) or a dedicated navigation

radio control panel. Until the aircraft were on the final approach course, they would be separated vertically by a minimum of 1000 ft for the two approach streams. During this time, the airborne components

of the AILS system would perform the required electronic handshakes, via data link, between aircraft

and annunciate the availability of the system to perform AILS to the flight crew. (The equipment is
4

described in section “Hardware Architecture.”) The flight crew would then be cleared for the AILS

approach procedure, with a subsequent reduction of vertical separation between the approach streams.

Under normal conditions, no other AILS specific actions would be required of the flight crew.

Loss of AILS Capability

The loss of AILS capability could be caused by several factors such as hardware failure, loss of the

DGPS signal, loss of data link. The flight crew response to the loss of AILS is dependent on the situation at the time of the loss. Prior to the reduction of vertical separation between the approach streams or

the acceptance of the approach from ATC, normal ATC procedures are adequate for separation maintenance. Once the descent on the final approach has started, system or signal failure will activate the

climb-turn warning, requiring the flight crew to perform an immediate EEM (described later). In addition, aircraft within a predefined longitudinal distance on the other parallel approach are considered to

be “paired” for collision-alerting purposes. Loss of data link with these paired aircraft will also generate

a climb-turn warning; again an immediate EEM will be required.

Potential Loss of Lateral Separation

On the rare occasions that one aircraft flies off path and produces a potential collision situation with

an aircraft on the other approach, the AILS concept provides a series of alerts for both the intruding aircraft and the nonintruding, evading aircraft. Caution alerts are provided in both aircraft to heighten the

crew’s awareness to the developing situation (ref. 3). If the potential collision situation continues, warning alerts are then provided. Again, the AILS warning alert (the climb-turn alert) requires an immediate

EEM. Also these alerts are sequenced such that the intruding aircraft is alerted first. The normal

sequence for alerts for this rare event would be intruder-caution, evader-caution, intruder-warning, and

finally, evader-warning. If the flight crew of the intruder either correct the situation when they receive

the caution alert or they perform an EEM on their warning, the warning to the noninterfering aircraft

may never occur. This sequencing then penalizes the intruder first (with a climb-turn warning) and

reduces the ATC disruption that would be caused by both aircraft executing an EEM.

Emergency Escape Maneuver

AILS is fundamentally a procedures-based concept with conventional Instrument Approach Procedures used as a basis for a “normal” operation. In the rare event that a normal operation does not

occur—that is, an aircraft flies off its approach and threatens another—the AILS concept relies on a

fixed documented procedure to minimize the collision risk. Based on previous analytical efforts and

industry studies (refs. 2, 4 to 9), it was determined that a maneuver in which an aircraft climbed, accelerated, and turned 45° away from the approach path of the other aircraft would provide a simple yet

effective means for dealing with a potential collision situation. This maneuver would be part of the published Instrument Approach Procedures (see fig. 6 for an example) and would be performed whenever

an AILS collision alert warning is activated. This climb-turn procedure is defined as an EEM. Also note

that reference 4 describes the advantages that a climb-turn maneuver has relative to a climb-only

maneuver.

Because the occurrence of an EEM is considered to be very infrequent, the cost of implementing

autopilot or flight guidance information for the EEM was considered to be prohibitive relative to the

benefit. The EEM is procedural and is performed without unique autopilot or flight director guidance.
5

Hardware Architecture

The AILS concept requires a DGPS (or equivalent) navigation source, an aircraft-to-aircraft data

link, AILS alerting logic, and supporting flight crew displays. For the aircraft-to-aircraft data link, the

Automatic Dependent Surveillance Broadcast (ADS-B) format (ref. 10), which provides aircraft state

data and custom operation’s specific data packets, will satisfactorily provide for all AILS requirements.

The current AILS hardware architecture, developed primarily by Honeywell, Inc., places the AILS

alerting functions into the Traffic Alert and Collision Avoidance System (TCAS) hardware (fig. 7).

Several advantages to this design are first, there needs to be interoperability between TCAS and the

AILS alerting; that is, while AILS should provide alerting of the appropriately “paired” aircraft, TCAS

alerting should still be available for all other aircraft. Second, by using the standard TCAS visual and

audio inputs into the flight deck display equipment, no new aircraft cabling is required for that part of

the installation.

Alerting Algorithm Description and Associated Displays

Table 1 provides a summary of the AILS alerts. From this table, it can be seen that the six AILS

alerts can actually be depicted as three alert sets, each with two levels of alert states.

Table 1. AILS Alerts and Thresholds

(a) Alerts

Alert state Alert level Representation Description Visuala Audio

Localizer Advisory LOCALIZER Ownship is off centerline by one half path

width (traditional one half full-scale error on

lateral deviation indicator)

Localizer Caution LOCALIZER Ownship is off centerline by full path width

(traditional full-scale error on lateral deviation indicator)

Path Caution PATH Path parallel

approach

Ownship performance producing possible

collision situation

Path Warning CLIMB TURN Climb turn Ownship performance producing probable

collision situation

Traffic Caution TRAFFIC Traffic parallel

approach

Ownship being threatened with possible

collision

Traffic Warning CLIMB TURN Climb turn Ownship being threatened with probable

collision

a

Visual alerts are color coded as follows:

Advisory: cyan

Caution: amber

Warning: red
6

Localizer Alerts

The LOCALIZER alerts are the simplest of the AILS alerts and only provide an indication of the

lateral tracking performance of ownship. A LOCALIZER advisory alert is issued whenever ownship

deviates farther than one half the width of the lateral boundary from the approach path centerline. From

a piloting standpoint, this is the traditional half-scale needle deflection (or greater) on the Course Deviation Indicator (CDI). For the aircraft configuration used in this test, the alert is presented on the Electronic Attitude Director Indicator (EADI) in the same location as the TCAS messages. An example of

this alert is provided in figure 8. A second LOCALIZER alert is issued whenever ownship deviates farther than the full-scale width of the lateral boundary from the approach path centerline. From a piloting

standpoint, this is the traditional full-scale needle deflection on the CDI. This localizer caution alert is

similar to the LOCALIZER advisory alert, except that it is in amber.

Path Alerts

Although the major safety factor for an AILS operation is based on accurately flying the approach

path, most of the AILS technology focuses on the alerting algorithms for the collision risk unique to an

AILS operation. This focus is similar to the process used in the Precision Runway Monitor (PRM)

development, where the qualities of flight path performance for parallel ILS approach operations are

well-known, but the level of safety needed to conduct these operations at reduced runway separations

dictate an enhanced collision alerting capability. Therefore, although the localizer alerts described previously only deal with simple off-path performance, the remaining AILS alerts are based solely on the

collision risk between actual pairs of aircraft.

The two-level set of AILS “PATH” alerts is designed to aid in avoiding collisions in the event that

the ownship maneuvers in a manner that would threaten the adjacent aircraft. For these alerts, the

onboard alerting algorithm uses state information from the traffic on the parallel approach, transmitted

by ADS-B, to detect situations where the potential path of the ownship may be threatening the adjacent

traffic. If this situation occurs, the onboard alerting system generates a PATH caution alert as this situation begins to evolve. This alert is intended to heighten the crew’s awareness of their flight path management and traffic situation. At this time, the crew should be taking action to place their aircraft back

on course. As the path performance further degrades and the collision danger becomes more imminent,

a PATH warning alert is generated. In this situation, the annunciation of this warning alert requires the

flight deck crew to execute an EEM.

The basic intrusion alerting algorithm, referred to as the “segmented alerting algorithm,” is

described in reference 9. This algorithm was refined by Langley and Honeywell personnel; intruder

alerts were added to the initial design along with several other enhancements. In simple terms, the

Table 1. Concluded

(b) Collision alert thresholds

Alert state Alert level Alert area threshold, ft, for— Alert time

Vertical Lateral Longitudinal threshold, sec

Path Caution 1500 1500 4000 25

Path Warning 1100 1100 3000 19

Traffic Caution 1300 1300 3500 22

Traffic Warning 900 900 2500 16
7

PATH collision predictions are time based around a predefined volume centered about the adjacent

“protected” aircraft. For the PATH caution alert, a volume defined as ±1500 ft vertically, ±1500 ft laterally, and ±4000 ft longitudinally centered about the adjacent aircraft is used. The protected airspace is

elliptical in the horizontal plane and is always centered on the protected aircraft. With state information

from each aircraft and the other aircraft assumed to fly its nominal approach profile, both aircraft positions are incrementally estimated along their potential ground tracks for a period of 25 sec, which is

defined as the alert threshold time for this alert. If the projected position of ownship falls within the

defined volume centered around the projected position of the adjacent aircraft, a PATH caution alert is

generated by the AILS system on ownship.

The segmented alerting aspect of this algorithm is based on the generation of a family of projected,

potential ground tracks, derived as a function of the turn rate of ownship. The first segment is generated

with the assumption that ownship is not turning. Subsequent segments use the actual turn rate of ownship, but vary the time in the turn, up to a time interval equal to the alert threshold time (again, 25 sec

for the PATH caution alert). Figure 9 illustrates this concept; in this illustration, ownship is turning to

the right. The first segment, portraying the current instantaneous ground track, does not take the turn

rate of ownship into account. The rightmost segment assumes that ownship is turning for the entire alert

threshold interval. One of these segments will generate a PATH caution alert, where the projected position of ownship will be within the PATH caution alert volume of the adjacent aircraft.

The PATH caution alert is annunciated to the flight crew through both auditory and visual means. A

voice alert is provided with the phrase “path parallel approach” spoken twice. Visually, the message

“PATH” is presented on the EADI in the color amber (fig. 10(a)). As an enhancement to pilot situation

awareness, the ownship symbol on the navigation display (ND) is also color coded amber to highlight

the fact that it is the performance of ownship that is causing the alert (fig. 10(b)). Because of the relative

closeness of the adjacent aircraft, AILS uses a nonstandard, higher resolution ND map scale. For this

implementation, the minimum map scale was 2.5 nmi, whereas traditional convention is typically a

minimum of 5 or 10 nmi.

The PATH warning alert, which is for a more critical situation than the PATH caution alert, uses an

alert volume defined as ±1100 ft vertically, ±1100 ft laterally, and ±3000 ft longitudinally and an alert

time threshold of 19 sec (table 1). The segmented alerting algorithm works in the same manner as

described for the PATH caution. This alert is also annunciated to the flight crew through both auditory

and visual means. Since an immediate EEM is the correct response to this alert, the voice alert phrase is

“climb turn,” spoken twice, and the message “CLIMB TURN” is presented on the EADI in the color red

(fig. 11). In addition, the ownship symbol on the ND is also color coded in red.

Traffic Alerts

Like the PATH alert, the AILS “TRAFFIC” alert is also a two-level set that is designed to aid in

avoiding collisions in the event that the adjacent aircraft maneuvers in a manner that would threaten

ownship. This alert set is obviously the “other side” of the alerting scheme. Again with the state data of

ownship and the adjacent aircraft, the onboard alerting algorithm determines if a situation is evolving in

which the adjacent aircraft is threatening ownship. If this situation occurs, the onboard alerting system

generates a TRAFFIC caution alert. This alert is intended to heighten the crew’s awareness of the traffic

situation. No crew action is required for a TRAFFIC caution alert. As the collision danger becomes

more imminent, a TRAFFIC warning alert is generated. In this situation, the annunciation of this warning alert requires the flight deck crew to execute an EEM.
8

The TRAFFIC caution alert uses an alert volume defined as ±1300 ft vertically, ±1300 ft laterally,

and ±3500 ft longitudinally and an alert time threshold of 22 sec (table 1(b)). The segmented alerting

algorithm described again centers the alert volume about ownship. The significant difference between

this and the PATH alert calculations is that the future position of ownship is projected along its

approach path while the position of the adjacent aircraft is projected along the family of turn segments

(fig. 12). In this regard, the alerting calculations are performed for the other side relative to the PATH

alerts.

As with all other potential collision alerts, the TRAFFIC caution alert is annunciated to the flight

crew through both auditory and visual means. A voice alert is provided with the phrase “traffic parallel

approach” spoken twice. Visually, the message TRAFFIC is presented on the EADI in the color amber

(fig. 13(a)). On the ND, the adjacent aircraft is now presented in a manner similar to a TCAS traffic

advisory (TA) (fig. 13(b)). This symbology is augmented over basic TCAS in that the ground-track

vectors of the traffic is included in the symbol. It should be noted that the ground-track information is

provided over the ADS-B data link.

The TRAFFIC warning alert, which is a more critical situation than the TRAFFIC caution alert,

uses an alert volume defined as ±900 ft vertically, ±900 ft laterally, and ±2500 ft longitudinally and an

alert time threshold of 16 sec (table 1(b)). The segmented alerting algorithm works in the same manner

as described for the TRAFFIC caution. This alert is also annunciated to the flight crew through both

auditory and visual means. Since an immediate EEM is the correct response to this alert, the voice alert

phrase is “climb turn,” spoken twice, and the message “CLIMB TURN” is presented on the EADI in the

color red. In addition, the traffic symbology changes to the conventional TCAS resolution advisory

(RA) red box for the TRAFFIC warning alert (fig. 14). Implementation details for the traffic and path

alerts are provided in reference 11.

Alert Priority and Sequence

The alerting system is designed such that only one of the six alerts can occur at any time and is

timed and sequenced to eliminate lower priority and nuisance alerts. For example, a LOCALIZER caution alert would not be issued after a PATH caution alert. All collision alerts have priority over the

LOCALIZER alerts. Also from examining the alert threshold times in table 1(b), it can be seen that the

intruding aircraft is alerted first to the collision risk. As noted previously, the normal sequence for alerts

for this rare event would be intruder-caution, evader-caution, intruder-warning, and finally, evaderwarning. This sequencing therefore penalizes the intruder first (with its climb-turn warning) and reduces

the ATC disruption that would be caused by both aircraft executing the EEM.

Evaluation Design and Conditions

The focus of this simulation experiment was to evaluate pilot performance, pilot acceptability, and

minimum miss-distances for the rare situation where an aircraft on one approach intrudes into the path

of an aircraft on the other approach. That is, this test only examined situations where another aircraft

flies off-path towards ownship, which activates ownship TRAFFIC alerts.

Previous analytical studies, showing a suitable level of operational safety, were based on the

assumptions that pilots would respond to the AILS TRAFFIC warning alerts in a timely and reasonably

aggressive manner. The assumptions used for this study, which greatly influenced the selection of the

alert threshold times, were a 2-sec pilot delay (pilot reaction time) followed by a roll rate of 4 deg/sec

until a roll angle of 30° was obtained. These assumptions, along with the selection of the alert

thresholds, were designed to produce a minimum miss-distance of 1200 ft. Therefore, the critical
9

objective criteria for this test, based on these assumptions, were pilot reaction time and minimum

miss-distance.

Test Subjects

The test subjects used in this study were Boeing 757 airline pilots, all with TCAS experience. A

total of 18 pilots were used for data collection, with data from 16 of these subjects used in the quantitative analysis. The selection criteria for the data sets are described in the section “Results.”

The subjects participated in a typical two-crew operational scenario, with the second crewmember

being a “confederate” of the research team. This crewmember confederate was a qualified transportcategory pilot. For this evaluation, the subject’s role was always that of the captain, pilot flying.

Independent Variables

This experiment was designed with three independent variables: intruder geometry, runway separation, and flight control mode. The dependent measures were pilot reaction time and miss-distance in a

full factorial test with randomized blocks design. For this study, pilot reaction time is defined as the

time interval between the initiation of the TRAFFIC warning alert and the pilot’s initial response to that

alert (e.g., autopilot disconnect, application of takeoff go-around power). Miss-distance is defined as the

slant-range distance between the aircraft centers of gravity.

In addition to pilot response to an AILS warning alert, the intrusion geometry and aircraft speed differential have an obvious impact on miss-distance for potential near midair collision (NMAC) situations. For this test, the general intrusion geometry selected was chosen for the worst-case situation from

the PRM analysis (ref. 1). For this situation, the intruding aircraft banked toward ownship at a moderate

rate until a 10° bank angle was obtained. This bank and resulting turn was maintained until a heading

change of 30° was obtained. At that time, the intruding aircraft continued at a constant speed along this

off-course heading of 30°.

Intruder Geometry and Relative Speeds

A secondary factor for the intrusion geometry is the lateral separation between aircraft at the start of

the intrusion event. This lateral separation distance itself was influenced by two factors: lateral runway

separation and the lateral offset angles for the approaches. Two runway separations were selected for

this test: 2500 ft and 3400 ft. The value 2500 ft was selected as the minimum since this is the current

lateral separation minimum due to wake vortex considerations for independent approaches. The value

3400 ft was chosen since this was the minimum value for PRM. In addition, because each approach path

was offset 2°, lateral separation was slowly reduced during normal operations as the aircraft approached

the runways. To take account of this factor, four different locations were selected along the approach for

the initiation of the intrusion event. These locations ranged from outside the final approach fix to an

intrusion turn that would generate an ownship alert at decision height.

As in any potential collision situation, large differences in relative speeds tend to increase the collision hazard. For this study, a 30-knot speed difference between the intruder and the ownship was considered to be the maximum difference and was used also as the maximum in the analytical studies.

Intruder profiles, therefore, had intruder speeds set at 30 knots faster and 30 knots slower than ownship.

One other variable that was included in the definition of the intrusion geometries was the planned

crossing point along the approach path of ownship for the intruder, assuming that the ownship did not

maneuver. Five points were used: 2000 ft ahead of ownship, 1000 ft ahead, a direct collision, 1000 ft
10

behind, and 2000 ft behind ownship. All these points would activate a TRAFFIC warning alert on

ownship.

Aircraft Control Modes

The aircraft control mode, manual or autopilot, prior to an AILS warning alert was considered to

potentially affect pilot response time. That is, the additional pilot task of disconnecting the autopilot or

autothrust system prior to the manual execution of the EEM may increase the assumed pilot delay interval (2 sec) for the EEM. Because of this delay, one of the independent variables of the test design was

the control mode prior to the TRAFFIC alert.

Intruder Runway

To maintain a reasonably small scenario set while creating seemingly novel situations for the test

subjects, intruder profiles were used for approaches to both left and right runways. The intruder profiles

were generated for the right runway scenarios and then mirrored for the left runway.

Pilot Run Matrix

Table 2 is a representative run matrix for a subject pilot. The major blocking factors were control

mode and runway separation. Each pilot flew 24 approaches, with 20 of these approaches containing

intrusion events. The test matrix itself was designed for 16 subjects; this resulted in a total of

384 approaches. The ordering of the scenarios for each pilot was counterbalanced by these major

blocking factors as well as the intruder geometry, which included nonmaneuver miss-distance, intrusion

point, and intruder speed differential.

Table 2. Run Matrix for Pilot 1

Run Control

mode

Runway

separation,

ft

Nonmaneuver

miss-distance,

ft

Intrusion

point

Intruder

runway

Intruder speed

difference,

knots

1 Autopilot 3400 −1000 1 Left −30

2 Autopilot 3400 0 3 Right +30

3 Autopilot 3400 1000 4 Left −30

4 Autopilot 3400 2000 2 Right +30

5 Autopilot 3400 No intrusion Left −30

6 Autopilot 3400 −2000 2 Right −30

7 Autopilot 2500 −2000 1 Left +30

8 Autopilot 2500 No intrusion Right +30

9 Autopilot 2500 2000 1 Left −30

10 Autopilot 2500 1000 3 Right +30

11 Autopilot 2500 −1000 4 Right +30

12 Autopilot 2500 0 2 Left −30

13 Manual 3400 No intrusion Right −30

14 Manual 3400 1000 1 Right −30

15 Manual 3400 0 4 Left +30

16 Manual 3400 −1000 2 Right −30

17 Manual 3400 −2000 3 Left −30

18 Manual 3400 2000 3 Left +30

19 Manual 2500 2000 4 Right −30

20 Manual 2500 1000 2 Left +30

21 Manual 2500 −2000 4 Right +30

22 Manual 2500 No intrusion Left +30

23 Manual 2500 0 1 Right −30

24 Manual 2500 −1000 3 Left +30
11

Aircraft Simulator

The aircraft simulator used for this evaluation was the Langley Integration Flight Deck (IFD) facility. This facility is a fixed-based, high-fidelity simulator (fig. 15) configured as the cockpit of the

NASA Boeing 757 research airplane and is used primarily to integrate, test, and evaluate new systems

and concepts prior to flight test. Both the simulator and aircraft flight deck can replicate a conventional

Boeing 757 aircraft, which was the condition for this evaluation. The one significant exception to this

standard flight deck layout was the addition of a supplemental ND control panel (fig. 16) which provided optional feature selection and a greater number of map scale selections. For this experiment, map

scales to 2.5 nmi, versus the 10 nmi minimum on a standard 757, were provided.

TCAS Integration

The AILS collision alerting algorithms (the PATH and TRAFFIC alerts) were hosted by Honeywell

in their TCAS 2000 avionics package. This TCAS unit was itself integrated and hosted in the Langley

Research System Integration Laboratory (RSIL). The RSIL is a special purpose laboratory that allows

the use of actual avionics flight systems in a simulator environment. As shown in figure 17, the

MODE-S/ADS-B, DGPS receiver, and DGPS control panel were all simulated in software. For this

study, the IFD simulation provided ownship state data, data from other traffic aircraft (described later),

and AILS specific interface control data to the RSIL facility. The RSIL facility processed these data into

the proper format (ref. 10) and then placed these data at the appropriate frequency on the ARINC 429

bus for the TCAS. AILS status and AILS alert states were then obtained from the TCAS 429 bus, postprocessed, and sent to the IFD simulation. The TCAS analog audio channel was sent directly to the IFD

simulator flight deck for output.

Traffic Generation

Traffic data for each of the defined scenarios were electronically generated prior to the simulation

study. For each scenario, the initial position of the traffic was based on the initial position of ownship,

the nonmaneuver miss-distance, the intrusion point, the speed differential, and the assumption that ownship would fly a nominal approach profile. As noted, the traffic data for the intrusion scenarios were

designed such that the intruding aircraft banked toward the approach path of the parallel runway at a

moderate rate until a bank angle of 10° was obtained. This bank and resulting turn was maintained until

a heading change of 30° was obtained. At that time, the intruding aircraft continued at a constant speed

along this off-course heading of 30°.

Because the relative geometry at the time of the ownship TRAFFIC warning alert was critical for

the repeatability of the event between each subject, the interpretation and interpolation of these traffic

data were synchronized relative to the variability of the speed of ownship such that the relative geometry at the time of the alert would be consistent.

Air Traffic Control Simulation

To add operational realism, an ATC simulation was used during this study. This simulation

included a remote ATC station and an audio link with the aircraft simulator. This ATC simulation provided normal approach control and airport tower instructions to the flight crew.
12

Pilot Training and Evaluation Sequence

The pilot training for this study attempted to represent a typical airline training package for a new

flight procedure involving new avionics equipment. This training package (appendices A to C) was

structured and scripted to provide for repeatability between the test subjects. The training consisted of a

50-min classroom briefing of the AILS operational concept, a 30-min simulator briefing, and 60 min of

simulator training. All training was presented by one of three retired airline captains, who was also used

as the first officer, the pilot not flying for the evaluation session (i.e., the confederate pilot). The AILS

evaluation session followed the simulator training. The evaluation session took approximately 4 hr to

complete.

The classroom briefing (appendix A) provided an overview of the AILS concept and specific training on the operational procedures (appendix B), checklists, equipment, and alerts. The EEM was

discussed in detail and was couched as a maneuver similar to the response to a wind shear alert. This

briefing also discussed the role of the confederate pilot, first officer, for the evaluation portion of the

test. The classroom training concluded with a 5-min written quiz to verify the subject’s understanding of

the presented material. Deficiencies evident through a less-than-perfect score were rectified before the

subject moved on to the simulator training.

Following the classroom briefing, the subject was taken to the IFD simulator for an introduction

(appendix C) to the simulator. This introduction was primarily a “differences” briefing; features unique

to the IFD, relative to the 757 configuration that the subject normally operated, were explained. This

briefing was then followed by the simulator training session.

The simulator training began with the subject pilot flying three approaches. (A detailed description

of the simulator training script can be found in appendix C.) The first of these approaches was a normal

approach with traffic on the other approach for the parallel runway. The second approach was similar

with the exception that a conventional wind shear alert was introduced just as the ownship approached

the final approach fix. The subject’s response time for this alert was measured to provide a baseline for

a secondary research study. The third approach included an intrusion for the other aircraft and a resulting TRAFFIC warning alert. Pilot responses to this alert were used to determine the effectiveness of the

classroom training and also to support a secondary research study.

After these three approaches, the confederate pilot, first officer, demonstrated all the AILS alerts.

The confederate pilot also demonstrated and provided comments on techniques for an EEM. The

remainder of this training period was then used to allow the subject pilot to become familiar with the

AILS alerts and practice the EEM.

Initial Conditions

For all the scenarios, both ownship and the parallel approach traffic were started on their respective

final approach courses at a distance approximately 14 nmi from their respective runway. One of the two

aircraft would already be established on its glide slope, while the other would be within 30 sec of glide

slope intercept. The ordering for this variable was counterbalanced in the test design. Because no pertinent situations occurred until both aircraft were well established on their respective glide slopes, this

factor was not included in the blocking for the data analysis.

For all the scenarios, both aircraft started at 165 knots (indicated) airspeed (KIAS). For one half of

all runs for each pilot, ATC would request a speed reduction to 135 KIAS at the final approach fix. Each

subject was briefed that while 165 KIAS is an unusually high speed for a Boeing 757 on final approach,
13

this higher than normal speed was required to support the conditions of a planned, subsequent flight test

of this concept.

Results

Quantitative Results

This experiment was designed with three independent variables: flight control mode, runway separation, and intruder geometry. The dependent measures were pilot reaction time and slant-range missdistance in a full factorial test with randomized blocks design.

During the data collection portion of this evaluation, several anomalies were noted in the recorded

data. Two of the first 16 subjects experienced a large number of simulator problems during the test.

Because of this, their test conditions were repeated with the two “spare” test subjects. The quantitative

data for these first two subjects were not used, with the test design remaining at 16 subjects. Of the

included runs, several other data problems were noted. One run that was designed to be an intrusion

scenario was incorrectly programmed such that no intrusion occurred. This run was discarded from the

analysis data set. In addition, three intrusion scenarios resulted in pilot reaction times of 0.0 sec. It was

determined that this situation could only have been an artifact of the data collection process. These three

data runs remained in the data set but were treated as “missing” values.

Table 3 and figure 18 illustrate the overall minimum, average, and maximum miss-distances (measured from each aircraft center of gravity) for the control mode and runway separation configurations.

Table 4 and figure 19 provide a similar illustration for pilot reaction times.

Table 3. Slant-Range Miss-Distance

Control mode

Slant-range miss-distance, ft, for runway

separation of— Miss-distance

category 2500 ft 3400 ft

Autopilot

1418.8 1187.9 Minimum

2169.1 2248.8 Average

3262.1 3303.2 Maximum

Manual

1302.1 1187.2 Minimum

2232.4 2295.1 Average

3326.3 3613.6 Maximum

Table 4. Pilot Reaction Times

Control mode

Reaction time, sec, for runway

separation of— Reaction time

category 2500 ft 3400 ft

Autopilot

0.040 0.200 Minimum

1.124 1.107 Average

2.680 2.440 Maximum

Manual

0.120 0.160 Minimum

0.839 0.947 Average

1.840 1.640 Maximum
14

As can be seen in tables 3 and 4, the lowest recorded miss-distance was 1187.2 ft, whereas the average reaction times were below 2.0 sec, regardless of the runway separation. A description of the analysis

on miss-distance and pilot reaction times is provided in appendix D. A synopsis of this analysis is as

follows.

Miss-Distance

Miss-distance was not significantly affected by either runway separation or flight control mode. In

addition, the design-goal mean miss-distance of 1200 ft with a 3σ range of ±500 ft was surpassed. The

actual mean miss-distance was 2236 ft with a 95-percent confidence interval of ±52.645 ft and a standard deviation of 479 ft.

Pilot Reaction Time

Pilot reaction time was not affected by runway separation. A statistically significant effect was

noted for the flight control mode, with autopilot use prior to the EEM leading to longer reaction times. It

should be noted, however, that with less than a 0.3-sec difference in mean values between the control

modes, this difference is probably not operationally significant. An overall average reaction time of

1.11 sec was noted for all conditions, which was well below the design-goal reaction time of 2.0 sec.

Qualitative Results

Subjective data were taken by a questionnaire (appendix E). As previously noted, 18 pilots participated in this test, with data only from 16 of these pilots used in the quantitative analysis. For the qualitative analysis, however, data from all 18 subjects were used. The one exception to this was in the

correlation between the quantitative performance data and the subjective responses relating to this

performance. In this regard, only the subjective data from the 16 subjects used in the quantitative analysis were included in the correlation of these specific performance questions, for example, flight control

mode.

A total of 18 questions were in the questionnaire, 12 were scaled and 6 were free-response questions. The 12 scaled, discrete questions were analyzed by using quantitative analysis methods, and the

free-response questions were summarized exactly as written by the subjects. For the scaled questions,

the answers were collected on a 5-point interval scale except for questions 9 and 10. The value of 1 was

considered to be the extreme negative end of the scale and the value of 5 was considered to be the

extreme positive end of the scale. Questions 9 and 10 discussed the flight control mode and were categorical (autopilot, manual, or “doesn’t matter”) and were scaled 1 to 3. To quantify and analyze the free

responses, a score of 1 to 5 was assigned to the answers, a value of 1 being an extremely negative comment and 5 being an extremely positive comment.

Scaled, Discrete Questions

The following questions were asked as the scaled, discrete questions on the questionnaire:

1. From a real-world line-operations viewpoint, would AILS be practical (please exclude equipment specific issues such as the displays and alerting system)?

2. Were the operational procedures clear and easy to understand?
15

3. Was the AILS training adequate?

4. Regarding your safety (collision risk) relative to the other aircraft, the situation was

5. Were the alerts clear and unambiguous (did you know what each alert meant)?

6. When you received an alert (advisory, caution, or warning), did you understand the necessary

response?

7. Was the procedure for the emergency escape maneuver (EEM) reasonable?

8. Was the emergency escape maneuver (EEM) easy to perform?

9. Which flight control mode would you use to fly the AILS approach?

10. Was your response to the EEM alert slowed by flying an autopilot approach (that is, the manual

takeover to perform the EEM)?

11. Do you think the 2.5-nmi map scale setting was necessary for AILS operations?

12. Did the background ATC communications give you a realistic perception of day-to-day

operations?

Responses from the scaled, discrete questions, excluding questions 9 and 10, are provided in

table 5. From these results, it can be seen that the general rating was “practical” or “reasonable.” The

one exception to this was in regard to performing the EEM, which was rated between “neither reasonable nor unreasonable” and “reasonable.”

The results to the two correlated, scaled questions, questions 9 and 10, relating to flight control

mode, are shown in figures 20 and 21, respectively. From figure 21 the subjects appear to incorrectly

perceive their reaction time performance relative to the actual performance data for the flight control

mode, with the overall rating showing no effect. However, it should again be noted that although the

quantitative results did show a statistically significant in performance, there was less than a 0.3-sec

difference in mean values between the control modes. This difference is probably not operationally

significant nor should it be expected that the subjects could perceive this small difference.

Table 5. Summary Statistics for Responses to Questionnaire Questions 1 Through 8, 11, and 12

Question Number of

responses

Mean Standard

deviation

Standard error

mean

1 18 4.5 0.616 0.145

2 18 4.7 0.428 0.101

3 17 a3.8 0.529 0.128

4 18 4.6 0.502 0.118

5 18 4.9 0.3234 0.0762

6 18 4.9 0.2357 0.0556

7 18 4.1 0.963 0.227

8 17 3.4 0.87 0.211

11 18 4.1 1.132 0.267

12 18 4.9 0.3234 0.0762 a

Question rated on a scale of 1 to 4.
16

Free-Response Questions

Although the responses to the free-response questions were scored, the primary intent of these questions was to solicit opinions concerning potential areas for improvement. The following questions

(questions 13–16 of the pilot questionnaire) were asked in the free-response questions:

13. Please provide your comments on the AILS operational concept.

14. While the AILS concept is not dependent on the specific implementation of the alerts that were

presented, it would be useful to know if you had any comments on the alerts.

15. While the AILS concept is not dependent on the specific implementation of the displays that

were presented, it would be useful to know if you had any comments on the displays.

16. Please provide your comments on the emergency escape maneuver (EEM).

Because the intent was to identify improvement areas, the following comments are biased toward

identifying these improvement areas and exclude most of the “favorable” comments. The pertinent

comments are as follows:

1. The visual “TRAFFIC” alert cue is too similar to a TCAS alert.

2. Following an EEM, the EEM “bug” needs to remain on the display until manually deselected.

3. The EEM required a good, aggressive maneuver, which is counter to the “smooth and slow” habits of typical airline flying.

4. The EEM should be evaluated using a maximum of 25° of bank angle.

5. TCAS traffic alerts should be inhibited for a longer period after an EEM. A “nuisance” traffic

alert was issued after the EEM.

On the positive side, the comments can generally be summarized by those of one of the subjects: “I

came into this study with a bias. I never thought it was a good idea to pack even more traffic into an

already crowded system. But now, I’m not so sure. The simulation seemed reasonable, doable and safe.”

The consensus from the subjects noted from these questions is as follows:

1. The operational concept is reasonable.

2. The AILS alert sequencing was good.

3. No significant display issues were noted.

4. The aggressive nature of the EEM requires the crew to be mentally prepared to execute it on

every approach. The EEM is aggressive without being violent.

5. Autothrottle using the TOGA (takeoff go-around) switch would be beneficial for the EEM.

6. At times, the target on the navigation display could be seen moving towards you, providing an

early indication of a problem.

7. The EEM training will be important.
17

Scoring results for the responses to the free form questions are provided in table 6. From these

results, the general ratings were all biased toward the positive or favorable, again noting that a score of

1 to 5 was assigned to the answers, a value of 1 being an extremely negative comment and 5 being an

extremely positive comment.

Summary of Results

The Airborne Information for Lateral Spacing (AILS) concept is designed to support independent

parallel approach operations to runways spaced as close as 2500 ft. This report describes the AILS operational concept and the results of a ground-based flight simulation experiment of one implementation of

this concept. The focus of this simulation experiment was to evaluate pilot performance, pilot acceptability, and minimum miss-distances for the rare situation that an aircraft on one approach intrudes into

the path of an aircraft on the other approach. From this simulation, the following results were obtained:

1. From an operational standpoint, the concept is reasonable.

2. The measured mean miss-distance was higher (better) than the design-goal mean miss-distance

range of 1200 ft with a 3σ of ±500 ft.

3. The actual mean miss-distance was 2236 ft with a 95-percent confidence interval of ±52.645 ft

and a standard deviation of 479 ft.

4. Miss-distance was not significantly affected by either runway separation or flight control mode.

5. Pilot reaction time was not affected by runway separation.

6. An overall mean reaction time of 1.11 sec was noted for all conditions, which was well below the

design-goal reaction time of 2.0 sec.

7. A statistically significant effect was noted for the flight control mode, with autopilot use prior to

the emergency escape maneuver (EEM) leading to longer reaction times. However, with less

than a 0.3-sec difference in mean values between the control modes, this difference is probably

not operationally significant.

8. The AILS alert sequencing was good.

9. No significant display issues were noted in the pilot commentary.

Table 6. Summary Statistics for Responses to Questions 13–16

Question Number of

responses

Mean Standard

deviation

Standard error

mean

13 18 4.3 1.018 0.24

14 18 3.3 1.074 0.25

15 18 3.4 1.114 0.27

16 18 2.9 1.022 0.24
18

10. The aggressive nature of the EEM requires the crew to be prepared to execute it on every

approach.

11. The EEM is aggressive without being violent.

From these results, it can be concluded that this operational concept, with supporting technology

and procedures, may provide an operationally viable means for conducting simultaneous, independent

instrument approaches to runways spaced as close as 2500 ft.
19

References

1. Precision Runway Monitor Demonstration Report. DOT/FAA/RD-91/5, Feb. 1991.

2. Waller, Marvin C.; and Scanlon, Charles H.: A Simulation Study of Instrument Meteorological Condition

Approaches to Dual Parallel Runways Spaced 3400 and 2500 Feet Apart Using Flight-Deck-Centered Technology. NASA/TM-1999-208743, 1999.

3. Flight Deck Alerting System (FAS). ARP4102/4, SAE, July 1988 (Reaffirmed May 1994).

4. Winder, Lee F.; and Kuchar, James K.: Evaluation of Vertical Collision Avoidance Maneuvers for Parallel

Approach. AIAA-98-4242, Aug. 1998.

5. Kuchar, James K.; and Carpenter, Brenda D.: Airborne Collision Alerting Logic for Closely Spaced Parallel

Approach. Air Traffic Control Q., vol. 5, no. 2, 1997, pp. 111–127.

6. Carpenter, Brenda D.; and Kuchar, James K.: A Probability-Base Alerting Logic for Aircraft on Parallel

Approach. NASA CR-201685, 1997.

7. Carpenter, Brenda D.; and Kuchar, James K.: Probability-Based Collision Alerting Logic for Closely-Spaced

Parallel Approach. AIAA-97-0222, Jan. 1997.

8. Pritchett, A.; Carpenter, B.; Asari, K.; Kuchar, J.; and Hansman, R. J.: Issues in Airborne Systems for CloselySpaced Parallel Runway Operations. Fourteenth Digital Avionics Systems Conference, AIAA/IEEE, Nov.

1995, pp. 140–145.

9. Koczo, Steve: Coordinated Parallel Runway Approaches. NASA CR-201611, 1996.

10. Minimum Aviation System Performance Standards for Automatic Dependent Surveillance Broadcast (ADS-B).

Doc. No. RTCA/DO-242, RTCA, Feb. 1998.

11. Samanant, Paul; and Jackson, Mike: Description of the AILS Alerting Algorithm. NASA/CR-2000-210109,

2000.
20

Figure 1. Parallel ILS approaches to runways spaced 2500 ft apart. Drawing not to scale.

Figure 2. Example of constant-width approach design to two closely spaced parallel runways. Drawing not to

scale.

Figure 3. Example of nonoverlapping, ILS-lookalike approaches using single 4° offset.

Figure 4. Example of nonoverlapping, ILS-lookalike approaches using dual 2° offsets.

Lateral boundary

crossover at ≈4 nmi

Path overlap

Typical localizer boundary 10 nmi

12 nmi

2000-ft path wide

(from centerline)

500-ft path wide

(from centerline)
21

Figure 5. Example of 2° offset approach to right parallel runway (offset is to right side).

1100 ft

Final approach course

intersection with

runway extended centerline

Decision height

design point

Final approach course

Runway extended

centerline

2° offset

2672 ft
22

Figure 6. Example of AILS instrument approach chart.

** or as

assigned

by ATC

PATUXANT APP 127.95

EASTERN SHORE TOWER 126.5

MISSED APPROACH

Climbing RIGHT turn to 3200

via direct MARZZ.

 If communications have not been established with ATC upon reaching 3200 ft.,

 proceed direct MARZZ.

RADAR REQUIRED

 *

0.8 4.1 NM 20.1 NM

1644 3200

CATEGORY A B C D

S-35R

CIRCLING

291 / 1/2 250 (300-1/2)

NA

WIOLA

WPT

WPT

ASHLY

AILS GLS RWY 35R

AILS GLS RWY 35R

WPT

CRABB

ELEV 41

EASTERN SHORE INTL (ETS)

WALLOPS, VIRGINIA

Emergency escape maneuver:

execute immediate climbing right

turn to 036, maintain 3200 *

SNOW HILL

112.4 SWL

Chan 71

GS 3.00

TCH51

**

10NM

 Simultaneous Parallel Approaches authorized with Rwy 35L - 3400 between the

 centerline of runways 35L and 35R.

 The FAC is offset 2 from the runway track; visual navigation shall be used beyond

 decision height.

MARZZ

SBY

1600

2100 M S A S W L 2 5 N M

135

225

27

R-150

111.2 SBY

CRABB

(IAF)

25

347

WIOLA

(FAF)

ASHLY

214

509

347

3200

VDL 117.65

RW35R

Ch387A

EASTERN SHORE INTL (ETS)

WALLOPS, VIRGINIA
23

Figure 7. Candidate hardware architecture.

Figure 8. Example of localizer advisory alert.

Ownship state data

DGPS correction

DGPS

receiver

Flight deck

displays

Flight

guidance

MODE-S

ADS-B

Ownship

transponder

reply

DGPS approach

path and path

deviation

Ownship state data and

approach data

DGPS approach path deviation

ADS-B output and

display data

Ownship

ADS-B

messages Approach data

Other aircraft transponder reply

Other aircraft ADS-B messages

Approach

selection Control

panel

TCAS

(AILS alerts)

Localizer advisory

alert (cyan)

Lateral deviation

pointer and scale
24

Figure 9. Determining at-fault collision potential of ownship.

Projected collision

volume of adjacent

aircraft at time T

Projected position

of adjacent

aircraft at time T Adjacent

aircraft

current

position

Nominal approach

courses

Ownship current

position

Projected

ground tracks

for various turn

times

Current

instantaneous

ground track
25

(a) EADI example of PATH caution.

(b) ND example of PATH caution alert.

Figure 10. Example of PATH caution alert on EADI and ND.

PATH caution

alert (amber)

Ownship symbol

for PATH caution

alert (amber)
26

Figure 11. Example of PATH warning alert on EADI.

Figure 12. Determining the intrusion threat.

PATH warning

alert (red)

Current instantaneous

ground track

Projected ground tracks

for various turn times

Adjacent aircraft

current position

Ownship

current

position

Nominal approach

courses

Projected position

of adjacent aircraft

at time T

Projected collision

volume of ownship

at time T
27

(a) EADI example of TRAFFIC caution alert.

(b) ND example of TRAFFIC caution alert.

Figure 13. Example of TRAFFIC caution alert on EADI and ND.

TRAFFIC caution

alert (amber)

Augmented TCAS TA

symbology (amber)
28

Figure 14. Example of TRAFFIC warning alert on ND.

Figure 15. Langley Integration Flight Deck layout.

Augmented TCAS RA

symbology (red)

Center console
29

Figure 16. Center console layout.

DISPLAY

ENGINE S TATUS

L R AU TO

PULL

L R

EVENT B OTH

RECORD

C OMPU TER

MAX IND

RESET

THRU ST R EF

SET

B RT

FL AP

DOWN

- 30

- 25

- 20

- 15

- 5

- 1

FLAP

UP

-0

FLAP

UP

DOWN

ARMED

S

T

A

B

T

R

I

M

S TAB TRIM

APL

NOSE

DN

APL

NOSE

UP

S

T

A

B

T

R

I

M

0

2

4

6

8

10

12

14

S TAB TRIM

APL

NOSE

DN

AP L

NOSE

UP

S

T

A

B

T

R

I

M

0

2

4

6

8

10

12

14

P

A

R

K

PA RK

1 - B TL DIS C H - 2

AR M ED

FWD

AR M ED

AF T

C

A

R

G

O

F

I

R

DI SC H DISC H E

DIS C H A PU

AP U BT L

D IS CH

118 .500 120

TES T

ILS

F

RE

Q

F

C

R

S

T FR

FREQ SEL

1 1 8. 5 00 1 2 0. 3 2 5

VHF COM

R UDDER T RI M

NOSE LE FT N OS E RI G HT UNIT S

1 5 1 0 5 0 5 10 1 5

A ILE R ON

L EF T

W ING

DOWN

RI GHT

WI NG

DOW N

NOS E

L EF T

N OS E

R RI GHT

U

D

D

E

R

DIS C H

E N G B TL

1 DIS C H

DIS CH

L

E

F

T

R

I

G

H

T

E N G B TL

2 DI SC H

LENG

OVH T

R E NG

OVH T

T FR

FREQ SEL

11 8 . 50 0 1 2 0. 3 25

VHF COM

1200

ABO VE ABS

BELOW RE L

T ES T

ST BY

XPD R TA

T A/ RA

FAIL

I DENT

L R

ABOVE ABS

BE LOW R EL

N N

T CAS / AT C

NAV DISPLAY

T CAS

ON

ON

ARPT

ON ON

W XR

ON

BRT

WPT

ON

MAP

PLAN

RMI

ILS / APP

5 10

20

40

8 0 1 60 3 20

R/ ARC TNAV

DATA N/ AID

PFD

STAR ON ON ON

RWY FLTDIR

OXY

BOOM

MIC SELEC T OR

L VHF IN C VH F R PA T

LV OR R VOR

L IL S C ILS R ILS

LA DF

FLT

C AB IN

PPT

L HF R

VOICE

RANGE

BOTH

MKR

O XY

BO OM

MIC SELECT OR

LVHF IN C VHFR PA T

L VOR R VO R

L ILS C ILS R ILS

L ADF

FLT

C A BIN

PPT

L HF R

VO ICE

RAN GE

BOTH

MKR

NORM

CUT

OUT C R

S TAB TR IM

FUEL CO NTRO L

RU N

L R

CUT OFF

E NG

VAL VE

SPAR

VAL VE

R EV

IS LN

ENG

VALVE

SP AR

VALV E

VOR ILS

VOR

ILS

PLAN

FULL MAP

EXP

1 0

2 0

4 0

8 0 16 0

3 20

MAP

NA V AID ARP T RT EDATA WPT

WX R

HS I

RANGE

BRT

RS T

ADI

DFR EF BRT

MAP WX TEST

LO MAX

TILT

15

-15

10

-10

5

-5

0

VOR ILS

VOR

ILS

PLAN

FU LL MAP

EXP

10

2 0

40

80 1 60 320

MAP

NAV A ID ARPT RT EDATA WPT

WX R

HSI

R ANG E

B RT

R ST

ADI

DFREF B RT

Research navigation

display control panel
30

Figure 17. Langley Integration Flight Deck Simulation and Langley Research System Integration Laboratory

layout.

Figure 18. Slant-range miss-distance.

Langley Integration Flight Deck

AILS status

AILS alerts

Other data

Ownship data

Traffic data

Environment data

Other data

Other avionics

TCAS

Langley Research System Integration

Laboratory

Minimum

Average

Maximum

Slant-range

miss-distance, ft

4000

3000

2000

1000

0

2500 3400 3400 2500

Autopilot Autopilot Manual Manual

Control mode

Runway separation, ft
31

Figure 19. Pilot reaction time.

Figure 20. Distribution of responses to question 9.

Figure 21. Distribution of responses to question 10.

0

.5

1.0

1.5

2.0

2.5

3.0

Minimum

Average

Maximum

2500 3400 3400 2500

Autopilot Autopilot Manual Manual

Control mode

Runway separation, ft

Reaction time,

sec

Doesn't matter

44 percent

Autopilot

39 percent

Manual

17 percent

Greatly

6 percent

Slightly

39 percent Not at all

55 percent
32

Appendix A

Classroom Briefing

1.0 Introduction of Instructor

Good morning, my name is ___________, and I will be your instructor and copilot for the next two

days. Before going into the details of the experiment, let me give you a brief summary of my flying

experience: [Provide background here, 1 minute].

2.0 Purpose & Scope of Experiment

AILS is an acronym that stands for Airborne Information for Lateral Spacing. Our mission for the

next two days will be to fly a number of closely spaced AILS approaches in a typical airline

environment.

3.0 AILS Concept

The AILS system enables aircraft to conduct closely spaced parallel approaches under instrument

conditions with a level of safety equivalent to that of closely spaced parallel approaches conducted

under visual conditions. Differential GPS position, data link, and computer projections of position are

utilized to provide timely information that enables the flight crews to keep each aircraft in its assigned

airspace or to make an evasive maneuver, should that become necessary.

If an aircraft deviates from its assigned airspace in today’s ATC system, considerable time is

required for the controller to detect the deviation, to issue appropriate instructions to the pilot, and for

the pilot to correct the flight path of the aircraft. By utilizing data link and computer projections, the

time required for an aircraft to respond is reduced significantly.

The probability that a pilot will ever need to make an evasive maneuver is very unlikely. It is estimated that an evasive maneuver will occur only once in every ten million approaches. This is equivalent

to one evasive maneuver in the careers of over 500 pilots.

AILS uses part of the TCAS system to data link the positions of each aircraft to the adjacent parallel

aircraft. The system is designed so that either TCAS or AILS will be operational whenever the aircraft

is above 200 feet AGL. When AILS becomes active, TCAS alerts are replaced with AILS alerts for the

adjacent parallel aircraft. You can verify this mode change by the presence of the AILS symbol on the

EADI or the EEM bug on the HSI. The TCAS system, however, remains operational for aircraft other

than the adjacent parallel aircraft. If the AILS system fails for any reason, both aircraft will receive a

“CLIMB TURN” warning at a predetermined distance and time.

ADS-B provides ground track information. This information can be seen as a vector displayed

above the TCAS diamond.

4.0 AILS Background

The term “closely spaced” means runway separations less than 4,300 feet, which is the normal

minimum for independent IFR operations. The FAA has approved a reduction to 3,400 feet centerline
33

separation at some airports if special ATC monitoring equipment is installed. The system is called

Precision Runway Monitor (PRM) and has been installed at Minneapolis/St. Paul airport.

Previous AILS experiments have explored the pilots’ reaction times, their ability to maintain an

accurate flight path, the capability of separation algorithms, the suitability of different instrument

displays and various runway centerline separations.

5.0 AILS Geometry & Approach Minimums

To ensure that the AILS approaches do not overlap and that minimum separation is maintained, the

localizer for each approach is offset by two degrees. The minimums for this approach are 250 feet and

1/2 mile visibility. It should be noted that the dual, two degree offset is just one of several ways to

configure the approach geometry for this type of operation.

6.0 AILS Safety Design

As previously stated, AILS approaches have been designed to provide a level of safety that is at

least equivalent to VFR operations with 4300 feet runway separation. Many of us feel that the level of

safety is greater than the current system. The safety features include the following:

• 1000-foot altitude separation prior to the beginning of the AILS approach.

• 2 degree offset approaches to ensure horizontal separation.

• Differential GPS accuracy.

• Automatic computerized detection of intruding aircraft—even when they are behind you.

• Advisory, Caution and Warning alerts that are designed to keep each aircraft in its assigned airspace.

• A Cautionary and a Warning alert that will advise you of any impending near mid-air collision

(NMAC).

• An Emergency Escape Maneuver that is designed to prevent near mid-air collisions, even if the previous alerts have not been effective.

7.0 AILS Alerts

Now let’s look at each of the alerts. Assume that AILS is active. You will be able to tell that it is by

the presence of a green AILS on the EADI (PFD) and a green EEM bug on the HSI (ND). Also, assume

that the other aircraft turns toward your aircraft and does not respond to any visual or aural alert. The

resultant alerts are summarized in these tables:
34

• The other aircraft would receive a cyan “LOCALIZER” advisory message on the EADI (PFD) when

that aircraft is 1 dot off course. There is no aural information given with this alert. The EADI (PFD)

and the HSI (ND) would look like this.

• The other aircraft would receive an amber “LOCALIZER” cautionary alert on the EADI (PFD) when

the aircraft is 2 dots off course. There is no aural information presented with this alert. This alert

would look like this. Notice that the localizer deviation scale on the EADI (PFD) and the aircraft symbol on the HSI would change to amber.

• The other aircraft would receive an amber “PATH” cautionary alert on the EADI (PFD) if the other

aircraft’s path becomes a potential threat to your aircraft. This alert includes an aural “PARALLEL

APPROACH PATH.” This situation would look like this. Notice that the aircraft symbol on the ND is

still amber.

• The other aircraft would receive a red flashing “CLIMB TURN” warning when the threat reaches a

predetermined time and distance threshold. The warning includes an aural “CLIMB TURN” command. This situation would appear like this on the EADI and the HSI. Note that the “CLIMB TURN”

and the aircraft symbol are now red in color.

Each of the above alerts, of course, should have caused the other aircraft to return to its assigned airspace. If the other aircraft does not respond to these alerts you will receive the following two alerts.

• If the other aircraft continues to be a threat to your aircraft you will receive an amber “TRAFFIC”

cautionary alert on the EADI (PFD) at a predetermined time and distance threshold. This alert is

accompanied by an aural “TRAFFIC PARALLEL APPROACH.” The alert would look like this on the

ALERTS IN COCKPIT OF AIRCRAFT THAT IS DEVIATING FROM COURSE

(Assumes other aircraft is on course)

Basis for Alert Parameter Alert Level Display Pilot Response Visual Audio

Course deviation 1 dot LOC Advisory LOCALIZER Return to Course

Course deviation 2 dots LOC Caution LOCALIZER Expeditiously

Return to Course

Potential threat to other

aircraft

Projected path Caution PATH PARALLEL

APPROACH,

PATH

Immediately

Return to Course

Imminent threat to

other aircraft

Projected path Warning flashing

CLIMB TURN

CLIMB TURN Execute EEM

ALERTS IN COCKPIT OF AIRCRAFT THAT IS BEING THREATENED

(Assumes threatened aircraft is on course)

Basis for Alert Parameter Alert Level Display Pilot Response Visual Audio

Potential threat from

intruder

Projected path

of intruder

Caution TRAFFIC TRAFFIC,

PARALLEL

APPROACH

Crew awareness,

Review

Procedure

Imminent threat from

intruder

Projected path

of intruder

Warning flashing

CLIMB TURN

CLIMB TURN Execute EEM
35

EADI (PFD) and the ND. Notice that the TCAS symbol on the HSI has changed to an amber filled

circle.

• If the other aircraft continues to be a threat to your aircraft you will receive a flashing red “CLIMB

TURN” warning on the EADI (PFD) at a predetermined time and distance threshold. This alert is

accompanied by an aural “CLIMB TURN” command. The situation would look like this. Note that

the intruding aircraft is now shown as a red filled square.

It is important to recognize that either aircraft could receive any of the six alerts. For example, you

could get the first four alerts if you deviated from your assigned airspace and the other aircraft could

receive the last two alerts. You should, therefore, be prepared for any of the alerts and know exactly

what you will do if you receive any of these alerts:

• If you receive a one dot “LOCALIZER” alert, you should return to the center of the localizer.

• If you receive a two dot “LOCALIZER” alert, you should expeditiously return to the center of the

localizer.

• If you receive a “PATH” alert, you should immediately and aggressively return to your assigned airspace. You should recognize that failure to do so may cause either or both aircraft to make an Emergency Escape Maneuver. You should also ensure that your hands and feet are in position on the

controls and quickly review the steps you will take in case you receive a “CLIMB TURN” alert.

• If you receive a “TRAFFIC” alert, you should assume that a near midair collision is imminent and you

should ensure that your hands and feet are in position on the controls and quickly review the steps you

plan to take if you receive a “CLIMB TURN” alert. Your performance during the Emergency Escape

Maneuver will be improved if you mentally rehearse the steps in the Emergency Escape Maneuver

just as you would for a rejected takeoff or a missed approach procedure.

• If you receive a flashing red “CLIMB TURN” warning you should immediately follow the steps of the

Emergency Escape Maneuver.

We will now discuss the details of the Emergency Escape Maneuver.

8.0 Emergency Escape Maneuver

As previously discussed, the probability of an Emergency Escape Maneuver is very low. If it is ever

needed, however, it must be accomplished quickly and precisely. The receipt of a “CLIMB TURN”

warning indicates imminent danger of a midair collision. This emergency must be considered with the

same concern and seriousness as a runway limited rejected takeoff (RTO), an engine fire or an emergency depressurization. The following are the correct steps:

Upon receipt of a “CLIMB TURN” Warning you should immediately and simultaneously

• Disconnect the auto-throttle, if engaged, and select go-around thrust.

• Disconnect the autopilot, if engaged, and increase pitch toward an initial pitch attitude of 15 degrees.

The rate of rotation should be approximately 3 degrees per second.

• As the rotation is initiated, aggressively roll into a coordinated 30 degree bank turn away from parallel

traffic. The roll rate should be approximately 5–10 degrees per second. A coordinated turn will require

about 25% of rudder input.
36

• Callout, “Go-around thrust; flaps 20”; after observing a positive climb, callout “Positive climb, gear

up.”

• Target airspeed for EEM is

- Low Speed: 145 knots—which is VREF30 plus 15 knots—High Speed: 165 knots—the same as

approach speed

• I will inform ATC that you are executing an Emergency Escape Maneuver.

• Continue the climb and turn until the Emergency Escape Maneuver altitude and the heading have been

achieved. I will inform ATC when you have reached the EEM heading and altitude.

The Emergency Escape Maneuver is different from and should not be confused with a normal goaround. Care must be taken not to follow the flight director or the approach raw data since they will still

be referenced to the normal approach. I will turn off your flight director if you ask me.

9.0 Other AILS Procedures

The following additional procedures apply to AILS approaches:

• A special AILS briefing will be conducted by the PF prior to entering the AILS portion of the

approach. This briefing will include the AILS landing runway, the direction of the emergency escape

turn, and the EEM altitude and heading. A sample briefing is the following:

“This will be an AILS approach to runway 35R. In the event of an Emergency Escape Maneuver, I

will make a climbing right turn to a heading of 036 degrees and will climb to 3200 feet.”

• The PF will announce when the green AILS heading bug and the green “AILS” on the EADI (PFD)

are in view. These symbols will remain on the display throughout the AILS approach. Either of these

is an indication to you that (1) the normal TCAS RA and TA alerts are inhibited for the other aircraft,

(2) the AILS alerts are operational, (3) your aircraft has entered the area of reduced lateral and vertical

separation from adjacent traffic, (4) strict compliance with the flight path is required and (5) compliance with warning and caution alerts is mandatory.

• Some airlines require their pilots to keep their hands and feet on the controls during autocoupled

approaches to loosely guard the controls and throttles. You should follow your own company’s training in this respect. Whenever you receive a “path” or “traffic” alert, however, you must ensure that

your hands and feet are on the controls and that you are prepared to disconnect the autothrottle and

autopilot and follow the EEM procedure if you should receive a “CLIMB TURN” warning.

10.0 AILS Matrix

In addition to the training runs, you will fly a number of different approaches during this experiment. The runs will be composed of

• Two runway separations of 3400 feet and 2500 feet.

• Two control modes—Manual and Auto-coupled.
37

• Two approach speeds: 135 and 165 knots.

• Several different scenarios.

Half of the approaches will be flown at 3400 feet runway separation while the other half will be at

2500 feet. Similarly, half of the approaches will be flown with the autopilot on and half will be flown in

the manual mode. All Emergency Escape Maneuvers will be flown in the manual mode, however.

Some of the approaches will have an intrusion requiring an Emergency Escape Maneuver—some will

not. Intrusions may occur at any point in the approach and the intruder may be faster or slower, above or

below, or left or right of your aircraft. I will inform you of the Autoflight mode, approach runway and

other pertinent information before each run.

11.0 AILS Call Outs

I will make the following normal callouts during all AILS runs:

• Glide slope alive

• Glide slope intercept point

• 1000 feet

• 500 feet

• Approaching minimums

• Minimums

You should respond in accordance with your own airline’s procedures.

In the event of an EEM, I will inform ATC of the following:

• Initiation of Emergency Escape Maneuver (EEM)

• Reaching EEM heading and altitude

12.0 Experimental Limitations of Crew Concept

Normal airline operations use the “crew concept” whereby all members of the crew participate in

the operation. Since this experiment will measure your ability to successfully fly AILS approaches, it is

necessary to restrict the input of the first officer as follows:

• I will not be able to help you with any part of the data runs that could interfere with the AILS experiment. I will, however, remind you of items you may have forgotten if they do not affect the experiment

results.

• I will not point out any course deviations by either aircraft during data runs. You should get this information from your flight instruments and the AILS alerts.

• I will not repeat or reinforce any of the alerts during data runs.
38

• I will not comment on your Emergency Escape Maneuver technique.

• I will not, however, mislead you. If you ask me a question and I cannot comment because of experimental constraints, I will simply reply, “No comment”.

13.0 General Information

The following is some general information about the experiment:

13.1 Simulator

The approaches will be accomplished in the Langley Integrated Flight Deck (IFD) simulator. The

configuration and performance are similar to a Boeing 757 aircraft—approximating that of the NASA

Boeing 757-200 research aircraft.

13.2 Type of Operation

All approaches will simulate normal passenger flights with passengers, flight attendants, and a

flight deck crew of two pilots.

13.3 Pilot Flying

You will be the pilot flying for all data runs. I will be the pilot not flying. Half of the runs will be

flown with the Autopilot; the other half will be flown manually. All emergency escape maneuvers will

be accomplished in the manual mode. Autothrottles will not be available in the manual mode.

13.4 Omitted Systems

All airplane systems are considered to be operational. ACARS and its printer are not installed.

13.5 Maintenance Items

There are no deferred maintenance items.

13.6 ATC

We will be using Langley’s ATC facility. It is staffed with a qualified Air Traffic Controller.

Parallel traffic will be on a different approach control frequency. Both aircraft will use the same tower

frequency.

13.7 Initialization Point

To conserve time, all approaches will begin on the final approach course, 14 NM from the runway

threshold. The initial conditions will be

• On localizer with the glide slope armed.

• Altitude of 3,200 or 4,200 feet.
39

• Autopilot and the speed mode of the autothrottle system will be engaged for autocoupled scenarios.

• Gross weight: 192,000 pounds.

• Gear up.

• Flaps 20 with speed 165 knots.

13.8 Completion of Run

The simulator is not equipped with a visual system. Each approach will be completed at the Missed

Approach Point (MAP) or upon the completion of the Emergency Escape Maneuver. I will say “reset”

when the run is complete.

14.0 Specific Pilot Flying Responsibilities

• For all approaches, you should follow the flight director to minimums, even if there is an amber Caution alert. At minimums, execute a normal missed approach procedure. In the event of a red Warning

(CLIMB TURN) you should immediately execute the Emergency Escape Maneuver.

• Normal SOP dictates that when the Autopilot is engaged, you should control all functions of the Mode

Control Panel except for the Altitude Selector. Altitude will be set by the PNF. When the Autopilot is

not engaged, the PNF will set everything on the MCP on your command.

• You should adjust the HSI mode and the range on the map as appropriate for the situation. As an initial guide, you can use the ILS/APP mode and the 5 NM RANGE. You may want to select the 2.5 NM

range as the parallel traffic gets closer. The lowest range available is 2.5 NM RANGE.

• You will be expected to make all decisions regarding flight path including speed, lateral, and vertical

control. I will not touch the control column or the throttles except to reduce thrust to maximum continuous thrust if it is exceeded.

• You will be expected to manage normal items associated with the approach including configuring the

aircraft and controlling the flight path. You may ask me to accomplish any item except lateral and vertical control of the flight path.

• After your escape bug is visible, you should brief me about the escape direction of turn, escape heading, and escape altitude. I will inform you if I hear any mistakes.

• On autocoupled approaches, comply with your company’s training regarding position of hands and

feet on/near controls. In the event of a “PATH” or “TRAFFIC” alert you must quickly place your

hands and feet on the controls and be ready to disconnect the autothrottle and autopilot.

• In the event of a “PATH” or “TRAFFIC” alert, you should quickly rehearse the specific steps of the

Emergency Escape Maneuver in case a “CLIMB TURN” warning occurs.
40

• If an Emergency Escape Maneuver is commanded you should immediately and simultaneously

1. Disconnect the Autothrottle and set go-around thrust.

2. Disconnect the Autopilot and initiate a climbing banked turn away from adjacent parallel

approach traffic. Use a rotation rate of approximately 3 degrees per second to an initial target

pitch attitude of 15 degrees. Use an aggressive roll rate of approximately 5–10 degrees per second to the target bank angle of 30 degrees.

3. Call “Go-around thrust, Flaps 20” and then “Positive climb, gear up” as you see an indication of

a positive climb.

4. Continue the climbing turn until you have reached the Emergency Escape Maneuver altitude and

heading. I will inform ATC when you have reached the EEM altitude and heading.

• Missed approach target speed for the low-speed run is 145 knots - VREF30 plus 15 knots. Missed

approach target speed for the high-speed run is 165 knots. The flaps are maintained at 20 degrees to

the EEM altitude.

• The EEM heading and altitude is 302° and 4200 feet for runway 35 left. For runway 35 center and

right, the EEM heading is 036° and the EEM altitude is 3200 feet.

15.0 Specific Pilot-Not-Flying Responsibilities

• I will initiate and conduct appropriate ATC communications.

• I will adjust the RANGE on my map as appropriate for the situation.

• I will be responsible for monitoring the aircraft flight path on both the EADI and the HSI. I will not,

however, inform you if you are off course.

• During manual approaches, I will set all functions of the MCP at your command. During automatic

approaches, I will set the altitude. For all approaches, I will operate the gear, flaps, and spoilers as you

request.

• In the event of an Emergency Escape Maneuver, I will retract the flaps to 20°, raise the landing gear

after an indication of a positive climb, and contact ATC.

• I will initiate the normal callouts as previously described.

• I will remind you of any items that you may have forgotten as long as they do not affect the experimental results.
41

16.0 Integrated AILS Crew Procedures

The following are the procedures that should be used for each approach.

16.1 Initialization

Flaps 20, speed 165, Gear UP; F/D on; Auto-throttle ON/OFF, Autopilot ON/OFF; Lateral guidance mode—LOC; Vertical guidance mode—Altitude Hold with Glide Slope armed. You should

assume a high speed approach (165 KIAS & 20 flaps) unless ATC specifically requests you to slow to

135 KIAS.

16.2 After the Emergency Turn Bug Is in View—Conduct Briefing

You should announce, “In the event of an Emergency Escape Maneuver, I plan to turn left to

302 degrees and climb to 4200 feet.” After this emergency turn briefing, we should both mentally

review the EEM action steps.

16.3 At the FAF or Glide Slope Intercept Point

I will announce “final approach fix” and will remind you of the emergency turn direction and heading if you have forgotten to conduct the AILS briefing.

16.4 At 1000 Feet

I will announce “1000 feet.” You should respond in accordance with your company’s procedure.

16.5 At 500 Feet

I will announce “500 feet.” You should respond in accordance with your company’s procedure.

16.6 Approaching Minimums

I will announce “approaching minimums” at 350 feet, and “minimums” at 250 feet.

16.7 If You Receive a “TRAFFIC” Alert

If not already in position, you should put your hands on the control wheel and throttles and be prepared to disconnect Autothrottle and Autopilot. Your feet should be ready on the rudder pedals. You

should mentally rehearse the specific steps you plan to take if you get a “CLIMB TURN” command.

16.8 If You Receive a “CLIMB TURN” Warning

You should immediately and simultaneously accomplish the procedure previously delineated.
42

Appendix B

Flight Manual Bulletin

INSTRUCTIONS TO SUBJECT PILOTS, AILS, JUNE, 1999

______________________________________________________________________________________

FLIGHT MANUAL BULLETIN

______________________________________________________________________________________

Insert following the BULLETINS tab. Record on the Bulletin Checklist

Revision 4.0, 6/7/99

AIRBORNE INFORMATION FOR LATERAL SPACING (AILS)

BACKGROUND INFORMATION

In 1993, work was begun on a flight deck-based system that would permit aircraft flying closely spaced

parallel approaches to operate in instrument conditions with the equivalent level of safety as under visual

conditions with the adjacent traffic in sight. The system, Airborne Information for Lateral Spacing (AILS) is

being evaluated at Wallops Flight Facility (WAL) and MSP.

Ground-based equipment required for this system includes a highly accurate approach path defined by

Differential GPS rather than conventional ILS localizer and glide path radio signals. This enables certain

modifications to be made to the approach paths, thus tailoring them to the specific requirements of AILS.

ILS terminology is retained for AILS approaches.

The fundamental conceptual difference between an AILS approach and all other approaches is that airborne

technology provides the primary separation assurance with the parallel approach traffic, rather than ATC.

This reduces the time delay of multiple people in the control loop.

The approach path is shown in the cockpit in the same manner as an ILS. The approach may be flown on

Flight Director or Autopilot. Approach paths for parallel runways may be offset 2° to provide separation on

final approach. For the offset approach, Decision Height is not less than 250 feet.

Airborne equipment unique to this system includes:

• Receiver for D-GPS approach path.

• Automatic Dependent Surveillance-Broadcast (ADS-B) transponder equipment with a refresh rate of

one-half second.

• Modified map display to provide additional scales of 5.0 and 2.5 nautical miles. To reduce map clutter on

the 2.5 scale, the scale index is 1 NM rather than 1.25.

• EADI and ND displays are modified to incorporate AILS requirements.

• TCAS is modified to enunciate warnings required by AILS.

• FMC database and logic modified to include AILS approaches.

Upon receiving clearance for an AILS approach, the flight crew will select the appropriate approach from the

menu on the FMS APPROACH page, verify and EXECUTE. This action by the flight crew causes the following operational changes:

• Data link is established with suitably equipped proximate aircraft.

• Verification of correct runway selection is made by the AILS system.

• Transition parameters from TCAS to AILS are established.

• D-GPS Required Navigational Performance (RNP) is confirmed by AILS.

• Special map scale (2.5 NM) is enabled for the approach.

______________________________________________________________________________________

B-757/767 FLIGHT MANUAL BULLETIN #99-06

PERFORMANCE & PROCEDURES PAGE 1 OF 3
43

No EICAS error messages are associated with the AILS approaches: Because this is a research effort, the

system is set up to work perfectly; therefore no error messages will be generated. However, in an operational environment the appropriate error messages would be listed here.

Resolution of potential and actual conflicts is prioritized so as to result in the maximum safety and minimum disruption to normal flow of traffic. The following principles are applicable to the design of AILS:

1. Alerting features are incorporated that help maintain each aircraft in its assigned airspace. Except for

deviations from the localizer course, transient excursions or excessive track angles will not necessarily

result in cockpit warnings. The deviation must pose a threat to another aircraft before the approach

is interrupted. This is done to avoid spurious emergency maneuvers.

2. The system recognizes that either or both aircraft may deviate from their respective assigned airspace

and become a threat to proximate traffic.

3. If deviation of one aircraft poses a potential threat to the adjacent aircraft, the priority of alerts is such

that the intruding aircraft is issued a Warning and broken out of the approach prior to breaking the adjacent aircraft out. The procedure initiated by the Warning message is called an Emergency Escape

Maneuver (EEM). It is displayed on the EADI as CLIMB, TURN, and includes the audio message,

“CLIMB, TURN.”

4. See Operating Procedures in this Bulletin for specific crew actions. As with any other time-critical

maneuver, pilots are expected to respond to an EEM immediately.

SUMMARY OF ALERTS

The following tables summarize those alerts that would be received by an airplane that fails to maintain its

prescribed flight path and ultimately poses a threat to the adjacent aircraft and those alerts that would be

received by an airplane that is being threatened by adjacent traffic. Either or both aircraft can be the

intruder or evader. Crewmembers must be prepared to respond appropriately to each of the six different

alerts.

______________________________________________________________________________________

B-757/767 FLIGHT MANUAL BULLETIN #99-06

PERFORMANCE & PROCEDURES PAGE 2 OF 3

ALERTS IN COCKPIT OF AIRCRAFT THAT IS DEVIATING FROM COURSE

(Assumes other aircraft is on course)

Basis for Alert Parameter Alert Level Display Pilot Response Visual Audio

Course deviation 1 dot LOC Advisory LOCALIZER Return to Course

Course deviation 2 dots LOC Caution LOCALIZER Expeditiously

Return to Course

Potential threat to other

aircraft

Projected path Caution PATH PARALLEL

APPROACH,

PATH

Immediately

Return to Course

Imminent threat to

other aircraft

Projected path Warning flashing

CLIMB TURN

CLIMB TURN

(repeating)

Execute EEM

ALERTS IN COCKPIT OF AIRCRAFT THAT IS BEING THREATENED

(Assumes threatened aircraft is on course)

Basis for Alert Parameter Alert Level Display Pilot Response Visual Audio

Potential threat from

intruder

Projected path

of intruder

Caution TRAFFIC TRAFFIC,

PARALLEL

APPROACH

Crew awareness,

Review

Procedure

Imminent threat

from intruder

Projected path

of intruder

Warning flashing

CLIMB TURN

CLIMB TURN

(repeating)

Execute EEM
44

OPERATING PROCEDURE

Air Traffic Control will vector or provide clearance to final approach in the conventional manner. Prior to

receiving clearance for the approach, ATC will advise each aircraft of the type aircraft and relative position of the proximate traffic.

This bulletin will be removed when the information is incorporated into the Flight Manual.

______________________________________________________________________________________

B-757/767 FLIGHT MANUAL BULLETIN #99-06

PERFORMANCE & PROCEDURES PAGE 3 OF 3

AILS APPROACH

NOTE

• AILS is not authorized with an engine inoperative or

any system irregularity that might compromise the

approach.

• Fly approach A/P or F/D.

• Fly normal missed approach A/P or F/D.

• Fly EEM MANUAL ONLY. No Autoflight guidance

is provided.

PNF FMS ARRIVALS . . . . . . . . . . . . . . . . . . . . AILS

Select AILS for the appropriate runway. Observe

AILS ARMED is enunciated on EADI

C, F/O APPROACH/LANDING BRIEFING

After receiving clearance for AILS approach, the following items will be added to the normal briefing:

• Use of autopilot on approach

• PNF monitor proximate A/C position

• Emergency Escape Maneuver (EEM)

PF, AUTOPILOT (AS DESIRED) . . . . . . . . ARMED

PF, AUTOTHROTTLE (AS DESIRED) . . . . . . . .ON

Although not mandatory for AILS approaches, use of

autopilot and autothrottle is recommended.

PNF, AILS ACTIVE . . . . . . . . . . . . . . . ANNOUNCE

Displays “AILS” on EADI. Flight mode Annunciations (PITCH and ROLL) are same as on ILS. Map

display changes to 2.5 NM scale.

NOTE

TCAS alerts from other than paired aircraft are active

during AILS approaches.

PNF, PROXIMATE TRAFFIC . . . . . . . . . MONITOR

PNF, AILS ACTIVE . . . . . . . . . . . . . . . . . MONITOR

If AILS Caution is enunciated (TRAFFIC Displayed

on EADI and aural TRAFFIC, PARALLEL

APPROACH), crew should review and be prepared to

execute an EEM.

CAUTION

If AILS Traffic Warning is enunciated (flashing

CLIMB, TURN displayed on EADI and aural

CLIMB, TURN, CLIMB, TURN), PF will accomplish the following procedure aggressively and

without delay:

PF, PNF EEM . . . . . . . . . . . . . . . . . . . . . . . INITIATE

PF, THRUST . . . . . . . . . . . . . . . . . . . . MAX RATED

Disconnect Autothrottles and aggressively position

throttles to Maximum Rated Thrust.

PF, PITCH ALTITUDE . . . . . . . . . . . . APPROX 15°

Disconnect Autopilot and rotate using approximately

3°/second rotation rate. Target speed is VREF30 plus

15 knots.

PF, BANK. . . . . . . . . . . . . . . . . . . . . . . .TARGET 30°

Aggressively roll into a 30° bank turn away from traffic. Continue turn to EEM Heading Bug (approx. 45°

away from adjacent approach course). Target altitude

as published for EEM.

CAUTION

Do not follow Flight Director during EEM. Flight

Director does not bias out of view and will continue

to command a return to approach path.

PNF FLAPS (ON ORDER) . . . . . . . . . POSITION 20

PNF GEAR (ON ORDER) . . . . . . . . . . . . . . . . . . . UP

Either pilot observe and call positive climb. Pilot flying call for gear up and pilot not flying retract the gear.

PNF EEM . . . . . . . . . . . . . . . . . . . . . . . . . MONITOR

PF advise ATC of EEM.

PF PUBLISHED EEM ALTITUDE. . . . .MAINTAIN
45

Appendix C

Simulator Briefing and Training Script

Note: Prior to arrival at the simulator, the simulator operator of the IFD will set up for training run

“A.” The simulator operator will go to operate and then place the simulator in “HOLD.”

1.0 Simulator Briefing and Training

1.1 Cockpit, General

• Seat and pedal adjustment.

• Verify that the subject’s seat & rudder position will permit adequate rudder position for the EEM.

• Nonstandard large digital clock for researcher use.

• Standard column and yoke.

• Have subject operate the autopilot disconnect switches. Stress the importance of disconnecting the

autopilot before starting the EEM.

• Point out that the simulator may not have the normal control breakout characteristics.

• Explain that the top of control column is warm because it has hydraulic fluid running through it.

• IFD has no visual system.

1.2 Communications

• Demonstrate use of MIC SELECT panels.

• Airplane (not simulator) has UHF radio control panel on overhead.

• Speakers may be used during simulator operations.

• Communications will be on L VHF COMM.

• ADF receiver must be ON to receive the AILS aural alerts.

1.3 Overhead Panel

• Simulator construction is not complete and several systems and switches do not work

• Yaw Damper, Hydraulic, Fuel, Bleed Air, and Anti-Ice are operative.

• IRS MODE SEL panel is early design and will not be used for this experiment.

• Fuel cross feed has single button.
46

1.4 Mode Control Panel (MCP)

• IFD has early style A/P ENGAGE switches (A/P & CWS); airplane has paddle-style levers.

• VNAV, CWS, & back course ILS do not work.

• Prior to each run, the instructor will set the MCP speed to 165 KIAS, set the flaps to 20 degrees, check

that the landing gear is UP, and turn both flight directors OFF.

• At the beginning of each run, the instructor will turn on both flight directors and engage the

ALTITUDE HOLD and APPROACH modes. If the run is autocoupled, the instructor will also place

the Left autopilot in the COMMAND mode and select the SPEED mode.

• At glide slope intercept, the instructor will set the altitude window to the missed approach altitude.

Note: Since the missed approach altitude and the EEM altitude are the same for this experiment, you

can re-engage the flight director for pitch and roll guidance after you have completed the EEM.

1.5 Electronic Attitude Deviation Indicator/Primary Flight Display (EADI/PFD)

• Left side display is modified for research purposes.

• Point out where the AILS status is displayed and where the various visual alerts (LOCALIZER,

PATH, TRAFFIC, CLIMB TURN) will appear.

• Point out the expanded localizer scale and its pointer.

1.6 Horizontal Situation Indicator/Navigation Display (HSI/ND)

• Left side display is modified for research purposes.

• Have subject operate the map scale selector knob and point out that the resolution is doubled when in

the AILS mode. Also point out 1.2 and the 1.0 NM labels on the 2.5 NM scale.

• Point out that the subject can use either the ILS/APP, HSI, MAP, or MAP CENTER mode of the HSI.

• Point out that each approach will start out with an erroneous wind value that will be integrated out in

approximately two minutes. The actual wind is zero for all simulator approaches.

1.7 Engine Controls

• RB 211 Engines (N1, N2, and N3) are installed on the airplane and are simulated in the IFD.

• Since all EEM’s will be accomplished manually, the takeoff/Go-Around (TO/GA) switches will not

be used.

• Point out and instruct the subject to operate the throttle disconnect switches.
47

1.8 Center Console

• The gray FMS Control Display Units (CDU) are Smith Industries units that have been modified for

research. The current database does not contain all the waypoints that are shown on the approach

plates.

• A set of CRT lighting controls is located on the pedestal immediately forward of the throttle quadrant.

• Trim Panel is moved forward to a position aft of, and adjacent to, the Engine Fire panel.

1.9 Speed Brake

• The speedbrake lever will be armed for all approaches in the simulator.

• In the airplane, the speedbrakes will not be armed if a touch-and-go is planned.

1.10 Flaps

Show the subject the 20° flap gate that will be used for normal go-arounds and for the EEM when the

speed is 135 KIAS. Note: When the speed is 165 KIAS, the flaps will already be at 20 degrees.

2.0 Simulator Training

Now we will begin the simulator training. The purpose of this training is to give you some hands on

AILS training to ensure that you are trained to proficiency before we begin the data runs. Trained to

proficiency means that you will be able to safely fly AILS approaches using the prescribed procedure.

All approaches in the simulator are initialized at a gross weight of 192.0, on the localizer, 14.0 NM

from the runway threshold. The winds for all approaches will be light and variable. If you reach the

250 foot decision height (DH) on any of the approaches, you should execute a normal missed approach.

After the FAF (10.0 DME), the runs will be flown at either of two stabilized approach speeds, 165

or 135 knots. All approaches are initialized with 20 degrees of flaps at an airspeed of 165 KIAS. You

should always plan to make a high speed approach (165 KIAS) unless ATC instructs you to slow to

135 KIAS. The gear should be down and the “BEFORE LANDING” checklist completed prior to the

final approach fix (leaving 3200 feet). The 135 KIAS speed is 5 knots above VREF30 speed of

130 KIAS. Go-around and EEM will be conducted at 145 KIAS or 15 knots above the VREF30 speed.

The flaps will be retracted to 20 degrees as part of the go-around or EEM procedure.

High speed approaches are initialized with 20 degrees of flaps at an airspeed of 165 KIAS. The gear

should be down and the “BEFORE LANDING” checklist completed by the 10.0 DME fix. While this

speed and configuration is nonstandard for airline operations, it is needed for research purposes. The

165 KIAS speed is 25 knots above the VREF20 speed of 140. Because of the excess speed, go-arounds

or EEM’s are also flown at 165 knots with the flaps remaining at 20 degrees.

On any approach, you may receive Caution or Warning alert other than AILS. You should respond

to these alerts in accordance with your airline training. For example, if you receive a WINDSHEAR

alert, respond as you have been trained by your company.
48

2.1 First Procedural Run—Manual

Instructor note: It is important that the instructor does not conduct any AILS training, including

reinforcement of the classroom briefing, during the first three runs. This is because part of the experiment is to determine the subject’s knowledge based solely on the classroom training. Explanation of

simulator differences and setup items are permitted. After the third run, a review of the key points of

AILS is appropriate and recommended.

SCRIPT: The purpose of the first run is to give you some practice in flying this simulator and using

normal procedures. AILS will not be on. I will function as a normal line first officer.

SETUP: Training scenario “A” (4,200 feet, on localizer RW 35L, 14 NM from touchdown, speed

165 knots, Flaps 20, Gear UP, AILS OFF, no intrusion, manual approach and a manually flown missed

approach). Note: Prior to operating, the instructor will verify the correct speed in the MCP, the corresponding flap setting, gear UP and both flight directors OFF. As soon as the simulator goes to operate,

the instructor will turn ON both FLIGHT DIRECTORS and select the ALTITUDE HOLD and

APPROACH modes.

CRITERIA: None—practice only.

Subject pilot will fly approach to a point approximately 250 feet AFE and then disconnect the autopilot and fly a normal missed approach. The following points will be discussed and emphasized:

• ATC communications (check in with tower, missed approach, EEM and completion of EEM.

• Normal approach call outs by PNF (glide slope intercept, 1,000 feet AFE, 500 feet AFE, approaching

minimums, minimums)

• Missed approach procedure (stress autopilot disconnect and appropriate pitch attitude for GA with

full power)

2.2 Second Run—Manual Control (With Unanticipated Windshear)

Instructor note: It is important that the instructor does not conduct any AILS training, including

reinforcement of the classroom briefing, during the first three runs. This is because part of the experiment is to determine the subject’s knowledge based solely on the classroom training. Explanation of

simulator differences and setup items are permitted. After the third run, a review of the key points of

AILS is appropriate and recommended.

SCRIPT: This is another manual run for you to practice normal procedures. You may or may not

receive an alert. If there is an alert, it may or may not command an emergency escape maneuver EEM.

Other standard alerts, such as windshear, may be introduced. You should use all the procedures and call

outs that we have talked about. This is an approach to runway 35L. I will be acting as an inexperienced

copilot and will not help you very much. Do you have any questions?

SETUP: Training Scenario “A” (4,200 feet, on localizer RW 35L, 14 NM from touchdown, speed

165 knots, Flaps 20, Gear UP, AILS OFF, no intrusion, manually flown approach, with windshear).

Note: Prior to operating, the instructor will verify the correct speed in the MCP, the corresponding flap

setting, gear UP and both flight directors OFF. As soon as the simulator goes to operate, the instructor

will turn ON both FLIGHT DIRECTORS and select, ALTITUDE HOLD and APPROACH.
49

CRITERIA: None—baseline data only.

• Discuss any procedural deviations.

• Windshear recovery maneuver is for data collection only and will not be debriefed.

2.3 Third Run—Manual Control (With Unanticipated Intrusion and EEM)

Instructor note: It is important that the instructor does not conduct any AILS training, including

reinforcement of the classroom briefing, during the first three runs. This is because part of the experiment is to determine the subject’s knowledge based solely on the classroom training. Explanation of

simulator differences and setup items are permitted. After the third run, a review of the key points of

AILS is appropriate and recommended.

SCRIPT: This is a third manual run for you to practice the AILS procedures. You may or may not

receive an alert. If there is an alert, it may or may not command an emergency escape maneuver EEM.

Other standard alerts, such as windshear, may be introduced. You should use all the procedures and call

outs that we have talked about. This is an approach to runway 35L. I will be acting as an inexperienced

copilot and will not help you very much. Do you have any questions?

SETUP: Training Scenario “B” (4,200 feet, on localizer RW 35L, 14 NM from touchdown, speed

165 knots, Flaps 20, Gear UP, AILS ON, with intrusion, manually flown approach). Note: Prior to operating, the instructor will verify the correct speed in the MCP, the corresponding flap setting, gear UP

and both flight directors OFF. As soon as the simulator goes to operate, the instructor will turn ON both

FLIGHT DIRECTORS and select ALTITUDE HOLD and APPROACH.

CRITERIA: None—baseline data collection only.

• Discuss any AILS procedural deviations (briefing, tracking, ground track symbol, preparation at

TRAFFIC alert, hands & feet on/near controls).

• Observe and debrief pitch, airspeed and heading control during EEM.

• Conduct quick review of AILS system (both EADI & HSI).

2.4 Demonstrate Intruder Alerts & EEM—Autocoupled & Manual

SCRIPT: The purpose of this run is to demonstrate the four levels of alerts that an intruder aircraft

would receive before you will have to alter your course. In this run, assume that we are the intruder aircraft. At a predetermined point, I will make a 10-degree turn towards the other aircraft. I will maintain

that heading so you can observe the four alerts. When I receive the red “CLIMB TURN” warning, I will

perform the EEM as we discussed earlier. Any questions?

SETUP: Training scenario “A” (4,200 feet, on localizer RW 35L, 14 NM from touchdown, speed

165 knots, Flaps 20, Gear UP, AILS on, with intrusion, autocoupled & manual approach). Note: Prior to

operating, the instructor will verify the correct speed in the MCP, the corresponding flap setting, gear

UP and both flight directors OFF. As soon as the simulator goes to operate, the instructor will turn ON

both FLIGHT DIRECTORS, select the SPEED mode of the autothrottle system, ALTITUDE HOLD,

APPROACH, and left Autopilot in COMMAND. Instructor will make a right 10 degree bank turn to a
50

heading of 021 degrees—30 degree intrusion—when the blue line of the extra monitor (behind subject)

crosses the nose of ownship.

CRITERIA: None—demonstration only.

• Demonstrate AILS special approach briefing.

• Instructor will point out one-dot Advisory.

• Instructor will point out two-dot Caution.

• Instructor will point out Path Caution.

• Instructor will point out and respond to “CLIMB-TURN” Warning.

2.5 Emergency Escape Maneuver (EEM) Proficiency—Autocoupled

SCRIPT: The purpose of this run is to practice and develop proficiency in EEM techniques. It is

important to recognize that the receipt of an EEM is truly an emergency, where you could be involved

in a midair collision if you do not take immediate, aggressive action. You will be given the opportunity

to practice several EEM’s.

The technique I use is the following:

When I first receive the Traffic alert, I will ensure that my hands and feet are in position on the controls and quickly review each step of the EEM. Upon receipt of the “CLIMB-TURN” Warning, I will

simultaneously

• Disconnect the autothrottle with my right thumb and aggressively push the throttles forward.

• Disconnect the autopilot with my left thumb and aggressively pull and rotate the yoke away from

adjacent parallel traffic. I will attempt to use a pitch rate of about 3 degrees per second and a roll rate

of about 5–10 degrees per second. In order to achieve this rate, it is necessary to use about 25 percent

of the rudder throw to coordinate the turn.

• Callout, “Go-around thrust; flaps 20”; after observing a positive climb, callout “Positive climb, gear

up.”

• Maintain a 30 degree bank turn away from parallel traffic until rolling out on the EEM heading bug;

30 degrees is the target bank angle and a slight overbank is acceptable.

• Target airspeed is VREF30 plus 15 knots—145 knots for slow speed runs and 165 knots for high

speed runs.

SETUP: Training scenario “B” (4,200 feet, on localizer RW 35L, 14 NM from touchdown, speed

165 knots, Flaps 20, Gear UP, AILS on, with intrusion, autocoupled approach). Note: Prior to operating,

the instructor will verify the correct speed in the MCP, the corresponding flap setting, gear UP and both

flight directors OFF. As soon as the simulator goes to operate, the instructor will turn ON both FLIGHT

DIRECTORS, select the SPEED mode of the autothrottle system, ALTITUDE HOLD and

APPROACH. The Left Autopilot will be placed in the COMMAND mode.
51

CRITERIA: None—Practice EEM to control pitch and bank. Observe and offer comments.

• Reaction time (approximately 2 seconds)

• Autopilot and Autothrottle disconnect

• Throttles manually advanced to approximately Go-around Thrust

• Pitch rate (approximately 3 degrees per second)

• Roll rate (approximately 5–10 degrees per second)

• Bank angle (approximately 30 degrees)

• Speed control (approximately 145 knots)

• Turns to correct EEM heading (302°)

• Levels at correct EEM altitude (4,200 feet)

Subject will demonstrate at least one satisfactory maneuver before proceeding to the full practice

runs.

2.6 Emergency Escape Maneuver (EEM) Proficiency—Manual

SCRIPT: The purpose of this run is to practice and develop proficiency in EEM techniques during a

manually flown approach.

SETUP: Training scenario “B” (4,200 feet, on localizer RW 35L, 14 NM from touchdown, speed

165 knots, Flaps 20, Gear UP, AILS ON, with intrusion, manual approach). Note: Prior to operating, the

instructor will verify the correct speed in the MCP, the corresponding flap setting, gear UP and both

flight directors OFF. As soon as the simulator goes to operate, the instructor will turn ON both FLIGHT

DIRECTORS, select ALTITUDE HOLD and APPROACH.

CRITERIA: None—Practice EEM to control pitch and bank. Observe and offer comments.

• Reaction time (approximately 2 seconds)

• Autopilot and Autothrottle disconnect

• Throttles manually advanced to approximately Go-around Thrust

• Pitch rate (approximately 3 degrees per second)

• Roll rate (approximately 5–10 degrees per second)

• Bank angle (approximately 30 degrees)

• Speed control (approximately 145 knots)
52

• Turns to correct EEM heading (302°)

• Levels at correct EEM altitude (4,200 feet)

Subject will demonstrate at least one satisfactory maneuver before proceeding to the full practice

runs.

2.7 Evaluation Run—Manual Control

SCRIPT: Now let’s put it all together. This will be a manually flown AILS approach with an intrusion and an EEM. You should use all the procedures and call outs that we have previously discussed.

This is an approach to runway 35L. I will be acting as an inexperienced copilot and will not help you

very much. At the conclusion of each run, I will debrief you. Do you have any questions?

SETUP: Training scenario “B” (4,200 feet, on localizer RW 35L, 14 NM from touchdown, speed

165 knots, Flaps 20, Gear UP, AILS on, with intrusion, manually flown approach). Note: Prior to operating, the instructor will verify the correct speed in the MCP, the corresponding flap setting, gear UP

and both flight directors OFF. As soon as the simulator goes to operate, the instructor will turn ON both

FLIGHT DIRECTORS and select ALTITUDE HOLD and APPROACH.

CRITERIA: Subject will demonstrate appropriate

• Reaction time (approximately 2 seconds)

• Autopilot and/or Autothrottle disconnect

• Throttles manually advanced to approximately Go-around Thrust

• Pitch rate (approximately 3 degrees per second)

• Roll rate (approximately 5–10 degrees per second)

• Bank angle (approximately 30 degrees)

• Speed control (approximately 145 knots)

• Turns to correct EEM heading (approximately 302° )

• Levels at correct EEM altitude (approximately 4,200 feet)

2.8 Evaluation Run—Autocoupled

SCRIPT: This will be an autocoupled AILS approach with an intrusion and an EEM. You should

use all the procedures and call outs that we have previously discussed. This is an approach to runway

35L. I will be acting as an inexperienced copilot and will not help you very much. At the conclusion of

each run, I will debrief you. Do you have any questions?

SETUP: Training scenario “B” (4,200 feet, on localizer RW 35L, 14 NM from touchdown, speed

165 knots, Flaps 20, Gear UP, AILS on, with intrusion, autocoupled approach). Note: Prior to operating,

the instructor will verify the correct speed in the MCP, the corresponding flap setting, gear UP and both
53

flight directors OFF. As soon as the simulator goes to operate, the instructor will turn ON both FLIGHT

DIRECTORS, select the SPEED mode of the autothrottle system, ALTITUDE HOLD, APPROACH

and left Autopilot in COMMAND.

CRITERIA: Subject will demonstrate appropriate

• Reaction time (approximately 2 seconds)

• Autopilot and/or Autothrottle disconnect

• Throttles manually advanced to approximately Go-around Thrust

• Pitch rate (approximately 3 degrees per second)

• Roll rate (approximately 5–10 degrees per second)

• Bank angle (approximately 30 degrees)

• Speed control (approximately 145 knots)

• Turns to correct EEM heading (approximately 302° )

• Levels at correct EEM altitude (approximately 4,200 feet)
54

Appendix D

Quantitative Data Analysis Details

A multivariate analysis of variance (MANOVA) was used to test the effect of the following factors

on both the reaction time and miss-distance: flight control mode, runway separation, scenario, aircraft

speeds, and interaction effects of these combined factors. The t-tests were conducted to test the following: the mean reaction time would be less than 2 sec and the mean miss-distance would be equal to

1200 ft. In addition, a chi-square (χ2

) test of the variance was conducted for a miss-distance of 1200

(±500) ft which translates to a standard deviation of 166 ft. These tests not only consider the individual

responses but also the correlation and covariances between and within the factors and responses.

Miss-Distance

The hypotheses used in the miss-distance MANOVA analysis are as follows:

Mean MDA = Mean MDM

Mean MDA ≠ Mean MDM

Mean MD25 = Mean MD34

Mean MD25 ≠ Mean MD34

where Mean MDA = Mean MDM (null hypothesis) states that the average miss-distance while flying in

the autopilot mode (MDA) is the same as the average miss-distance while flying in the manual mode

(MDM). The alternative hypothesis states that the average miss-distance while flying in the autopilot

mode is not the same as the average miss-distance while flying in the manual mode. Similarly,

Mean MD25 = Mean MD34 (null hypothesis) states that the average miss-distance while approaching

runways that are 2500 ft apart (MD25) is the same as the average miss-distance while approaching runways that are 3400 ft apart (MD34). The alternative hypothesis states that the reaction time is not the

same in these cases.

The MANOVA analysis (table D1) failed to reject both null hypotheses based upon a significance

level of α = 0.05. This means that based on the experimental results, there is neither a significant difference between MDA and MDM nor is there a significant difference between the mean MD25 and mean

MD34.

Table D1. Summary of Multivariate Analysis of Variance for Miss-Distance

Source Degrees of

freedom

Sum of squares Adjusted

mean square

F P

Sequential Adjusted

Control mode 1 237 938 241 913 241 913 1.05 0.306

Runway separation 1 413 047 413 047 413 047 1.79 0.181

Error 313 72 073 323 72 073 323 230 266

Total 315 72 724 308
55

For the t-test of the mean miss-distance, the specification was that the miss-distance must be

1200±500 ft. This specification translates to the following hypothesis:

Mean MD = 1200.0 ft

Mean MD ≠ 1200.0 ft

The null hypothesis states that the mean miss-distance is equal to 1200 ft. The alternative hypothesis

states that the mean miss-distance is not equal to 1200 ft. The null hypothesis was rejected (table D2).

The mean miss-distance was much larger (2236 ft) than the prespecified target of 1200 ft.

The χ2 test for the variance of the miss-distance showed that the recorded miss-distance variance is significantly larger than the specified one.

Pilot Reaction Time

The minimum pilot reaction time for each run was derived from three recorded flight control

responses: time to advance the throttle, time to pull the column, and time to turn the wheel. The number

of times that each control action was the minimum reaction time was examined. The results of this

examination are illustrated in table D3.

It should be noted that the subjects were briefed to advance the throttle in response to an EEM alert,

thus giving them power to climb and turn away from the intruder. From table D3, advancing the throttle

was the first response to the majority of the alerts (61%).

Table D2. Summary of Miss-Distance t-Test

Variable N Mean Standard

deviation

Standard

error mean

T P

Miss-distance 318 2236 479 26.9 38.57 0.0000

Table D3. Dominant Minimum Reaction Time According to Control Mode

Control mode Runway

separation

Minimum reaction time, percent, for— Grand total,

Throttle Wheel Column percent

Autopilot 2500 63 36 1

3400 75 24 1

Total 69 30 1 100

Manual 2500 51 41 8

3400 54 32 14

Total 53 37 11 100

Grand total 61 33 6 100
56

The hypotheses used in the average reaction time MANOVA analysis examining flight control

mode, autopilot or manual, prior to the EEM and runway separation are as follows:

Mean RTA = Mean RTM

Mean RTA ≠ Mean RTM

Mean RT25 = Mean RT34

Mean RT25 ≠ Mean RT34

where Mean RTA = Mean RTM (null hypothesis) states that the average reaction time while flying

in the autopilot mode (RTA) is the same as the average reaction time while flying in the manual

mode (RTM). The alternative hypothesis states that the average reaction time while flying in the

autopilot mode is not the same as the average reaction time while flying in the manual mode. Similarly,

Mean RT25 = Mean RT34 (null hypothesis) states that the average reaction time while approaching runways that are 2500 ft apart (RT25) is the same as the average reaction time while approaching runways

that are 3400 ft apart (RT34). The alternative hypothesis states that the reaction time is not the same in

these cases.

The first null hypothesis was rejected with a P-value of 0.0000 (table D4); this means that there is a

statistically significant difference between the mean RTA and the mean RTM. We failed to reject the

second null hypothesis; this means that there is not a significant difference between the mean RT25 and

the mean RT34.

In addition to flight control mode and runway separation, it was prespecified that the minimum

reaction time should be less than 2 sec; this translates to the following hypothesis:

Mean RT = 2.0

Mean RT < 2.0

The null hypothesis states that the average reaction time is equal to 2.00 sec. The alternative hypothesis

states that the average reaction time is less than 2.00. The null hypothesis was rejected with a P-value of

0.0000 (table D5). This means that based upon experimental results the average reaction time is indeed

below the 2-sec limit.

Table D4. Summary of Multivariate Analysis of Variance for Reaction Time

Source Degrees of

freedom

Sum of squares Adjusted

mean square

F P

Sequential Adjusted

Control mode 1 3.919 3.9088 3.9088 20.07 a0.0000

Runway separation 1 0.1594 0.1594 0.1594 0.82 0.366

Error 313 60.9515 60.9515 0.1947

Total 315 65.0299 a

Significant at α = 0.05.

Table D5. Summary of Pilot Reaction t-Test

Variable N Mean Standard

deviation

Standard

error mean

T P

Reaction time 316 1.0049 0.4544 0.0256 −38.93 0.0000
57

Appendix E

AILS Pilot Questionnaire

Please answer the following questions as accurately as you can. We want your personal opinion on

questions that are important to us. For each question, please mark the number that best describes your

opinion. Note that for the first seven questions, one of five answers is possible. For each question,

please select one of the numbers.

1. From a real-world line-operations viewpoint, would AILS be practical (please exclude equipment

specific issues such as the displays and alerting system)?

2. Were the operational procedures clear and easy to understand?

3. Was the AILS training adequate?

4. Regarding your safety (collision risk) relative to the other aircraft, the situation was:

not

practical

1

neither

practical

nor impractical

2 3

very

practical

4 5

not

clear

1

neither clear

nor unclear

2 3

very

clear

4 5

extremely

inadequate

inadequate adequate

1

neither

adequate

nor inadequate

2 3

excessive

4 5

never

clear

1

neither clear

nor unclear

2 3

always

clear

4 5
58

5. Were the alerts clear and unambiguous (did you know what each alert meant)?

6. When you received an alert (advisory, caution, or warning), did you understand the necessary

response?

7. Was the procedure for the Emergency Escape Maneuver (EEM) reasonable?

8. Was the Emergency Escape Maneuver (EEM) easy to perform?

9. Which flight control mode would you use to fly the AILS approach?

never

clear

1

neither clear

nor unclear

2 3

always

clear

4 5

never

1

sometimes

2 3

always

4 5

not

reasonable

1

neither

reasonable nor

unreasonable

2 3

very

reasonable

4 5

very

difficult

1

neither

difficult / easy

2 3

very

easy

4 5

autopilot doesn't

matter

1

manual

2 3
59

10. Was your response to the EEM alert slowed by flying an autopilot approach (that is, the manual

takeover to perform the EEM)?

11. Do you think the 2.5 nmi map scale setting was necessary for AILS operations?

12. Did the background ATC communications give you a realistic perception of day-to-day operations?

13. Please provide your comments on the AILS operational concept:

❏ No specific comment.

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

14. While the AILS concept is not dependent on the specific implementation of the alerts that were presented, it would be useful to know if you had any comments on the alerts.

❏ No specific comment.

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

greatly slightly

1

not at

all

2 3

not

important

1

no difference

2 3

very

important

4 5

not

realistic

1

somewhat

realistic

2 3

very

realistic

4 5
60

15. While the AILS concept is not dependent on the specific implementation of the displays that were

presented, it would be useful to know if you had any comments on the displays.

❏ No specific comment.

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

16. Please provide your comments on the Emergency Escape Maneuver (EEM).

❏ No specific comment.

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

17. During the experiment, did you pick up any technical cues about how the system is designed to help

you be more prepared for the EEM? (e.g., color changes, symbol changes, etc.) If so, please state

what they were, you may prefer to discuss it with the researchers.

❏ None evident to me.

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

18. Do you have any other comments?

❏ No other comments.

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________
Form Approved

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources,

gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this

collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson

Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

6. AUTHOR(S)

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

11. SUPPLEMENTARY NOTES

8. PERFORMING ORGANIZATION

REPORT NUMBER

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

14. SUBJECT TERMS

17. SECURITY CLASSIFICATION

OF REPORT

18. SECURITY CLASSIFICATION

OF THIS PAGE

19. SECURITY CLASSIFICATION

OF ABSTRACT

20. LIMITATION

OF ABSTRACT

15. NUMBER OF PAGES

16. PRICE CODE

NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)

Prescribed by ANSI Std. Z39-18

298-102

REPORT DOCUMENTATION PAGE

March 2001 Technical Publication

Simulator Evaluation of Airborne Information for Lateral Spacing (AILS)

Concept WU 576-02-11-17

Terence S. Abbott and Dawn M. Elliott

L-18036

NASA/TP-2001-210665

The Airborne Information for Lateral Spacing (AILS) concept is designed to support independent parallel approach

operations to runways spaced as close as 2500 ft. This report describes the AILS operational concept and the results

of a ground-based flight simulation experiment of one implementation of this concept. The focus of this simulation

experiment was to evaluate pilot performance, pilot acceptability, and minimum miss-distances for the rare situation in which an aircraft on one approach intrudes into the path of an aircraft on the other approach. Results from

this study showed that the design-goal mean miss-distance of 1200 ft to potential collision situations was surpassed

with an actual mean miss-distance of 2236 ft. Pilot reaction times to the alerting system, which was an operational

concern, averaged 1.11 sec, well below the design-goal reaction time of 2.0 sec. These quantitative results and pilot

subjective data showed that the AILS concept is reasonable from an operational standpoint.

Aircraft operations; Closely spaced parallel approach; Aircraft displays 71

A04

NASA Langley Research Center

Hampton, VA 23681-2199

National Aeronautics and Space Administration

Washington, DC 20546-0001

Unclassified–Unlimited

Subject Category 03 Distribution: Standard

Availability: NASA CASI (301) 621-0390

Unclassified Unclassified Unclassified UL