narrow runway

BOEING is a trademark of Boeing Management Company.Copyright © 2007 Boeing. All rights reserved.

Guidelines for Narrow Runway OperationsGuidelines for Narrow Runway Operations

Bruce LindstromThe Boeing CompanyBruce LindstromThe Boeing Company

Copyright © 2007 The Boeing Company Lindstrom.2

How Narrow Is Narrow?How Narrow Is Narrow?

● 45m is standard runway width (for most large commercial jet operations)

● As of March, 2002, there were at least 63 airports worldwide with runway width 30m or less, being served by 737,757 or 767 aircraft.

● Boeing has received various requests from operators for guidance in operating aircraft on runways as narrow as 23m (75 ft).

● 45m is standard runway width (for most large commercial jet operations)

● As of March, 2002, there were at least 63 airports worldwide with runway width 30m or less, being served by 737,757 or 767 aircraft.

● Boeing has received various requests from operators for guidance in operating aircraft on runways as narrow as 23m (75 ft).


Narrow Runway IssuesNarrow Runway Issues● Takeoff:

1.“GO” following engine failure2.“RTO” following engine failure3.Maximum recommended crosswind

● Landing:1.Adverse weather (pilot decision-making)2.Crosswind landing 3.Crosswind and engine failure4.Autoland considerations

● MMEL/Inflight Failures affecting directional control

● Ground Maneuvering and increased risk of FOD to wing-mounted engines

● Takeoff:1.“GO” following engine failure2.“RTO” following engine failure3.Maximum recommended crosswind

● Landing:1.Adverse weather (pilot decision-making)2.Crosswind landing 3.Crosswind and engine failure4.Autoland considerations

● MMEL/Inflight Failures affecting directional control

● Ground Maneuvering and increased risk of FOD to wing-mounted engines


Regulatory BackgroundRegulatory Background

● In CFR 14 Part 25 and JAR 25, there are currently no requirements to define a minimum runway width as part of the certification of an airplane type.

● No published AFM limitation.

● FAA does publish recommended runway design criteria in Advisory Circular 150/5300-13.

● ICAO also publishes recommended minimum runway width in Annex 14

● In CFR 14 Part 25 and JAR 25, there are currently no requirements to define a minimum runway width as part of the certification of an airplane type.

● No published AFM limitation.

● FAA does publish recommended runway design criteria in Advisory Circular 150/5300-13.

● ICAO also publishes recommended minimum runway width in Annex 14


Regulatory Background – Airworthiness StandardsRegulatory Background – Airworthiness Standards

● Runway width not directly addressed in FAR/JAR Part 25.

● FAR 25.149(e) does specify criteria to be used to determine minimum control speed on the ground (VMCG):– No credit for nose wheel steering…– Maximum 30 ft (9.14m) deviation from

centerline during recovery

● Runway width not directly addressed in FAR/JAR Part 25.

● FAR 25.149(e) does specify criteria to be used to determine minimum control speed on the ground (VMCG):– No credit for nose wheel steering…– Maximum 30 ft (9.14m) deviation from

centerline during recovery

Note: Regulatory VMCG basis assumes zero crosswind


Maximum Allowable Deviation and runway width…Maximum Allowable Deviation and runway width…

Initial offset?Initial

offset?

??

½ gear track½ gear track

Max DeviationMax Deviation

30 ft(9.1m)30 ft

(9.1m)


VMCG on a 45m (150 ft) wide RunwayVMCG on a 45m (150 ft) wide Runway

737-700 747-400

(based on 2m initial offset)


Sample 737-700 sea level example:

Narrow Runway VMCG Narrow Runway VMCG VMCG should be increased to provide adequate margins on narrow runways…

Our approach is to scale the permissible deviation to the runway width, and then quantify the affect on VMCG:

VMCG should be increased to provide adequate margins on narrow runways…

Our approach is to scale the permissible deviation to the runway width, and then quantify the affect on VMCG:

Runway Width Allowable deviation VMCG Adjustment

45m (Baseline) 9.1m (30 ft) baseline

Add 3-5 knots30m 6.1m (20 ft)

Note: The increased VMCG causes an increase in minimum field length required for takeoff in a VMCG-limited situation.


What About Rejected Takeoff? What About Rejected Takeoff?

● Notice that the increased VMCG we just discussed protects us for a continued takeoff after V1, following engine failure, but it slightly increases our potential exposure to an RTO.

● An equally important consideration is the effect of a narrow runway on the RTO.

● Notice that the increased VMCG we just discussed protects us for a continued takeoff after V1, following engine failure, but it slightly increases our potential exposure to an RTO.

● An equally important consideration is the effect of a narrow runway on the RTO.


RTO Physics RTO Physics

● Retard thrust on the operating engine as quickly as possible to remove thrust asymmetry

● Largest deviations occur on RTO…

● Retard thrust on the operating engine as quickly as possible to remove thrust asymmetry

● Largest deviations occur on RTO…

• Engine failure below V1 STOP!


Airspeed Effect on Maximum Deviation During RTOAirspeed Effect on Maximum Deviation During RTO

● Higher speed increases rudder effectiveness and increases airplane momentum prior to engine failure.

● Thrust asymmetry reduces at higher speeds

● Higher speed increases rudder effectiveness and increases airplane momentum prior to engine failure.

● Thrust asymmetry reduces at higher speeds

Conclusion: Worst case for directional control is encountered on RTO when engine fails at slow speed


Crosswind Accountability for Engine Failure on Takeoff Crosswind Accountability for Engine Failure on Takeoff

Boeing’s Recommended Crosswind Guidelinesare intended to address crosswind and engine failure.

FAR/JAR Part 25 VMCG definition assumes zero crosswind…

FAR/JAR Part 25 VMCG definition assumes zero crosswind…

Maximum Demonstrated

Crosswind does not address engine

failure…

Maximum Demonstrated

Crosswind does not address engine

failure…


737-6/7/8/900 Recommended Takeoff Crosswind Guidelines (45m runway)737-6/7/8/900 Recommended Takeoff Crosswind Guidelines (45m runway)

As published in the Flight Crew Training Manual (FCTM):As published in the Flight Crew Training Manual (FCTM):

*Winds measured at 10m (33 ft) tower height and apply for runway 45m or greater in width

** Takeoff on untreated ice or snow should only be attempted when no melting is present

Crosswind – Knots*

Runway Condition -600 -700 without / with

winglets

-800 or -900 without / with

wingletsDry 36 36 / 34 36 / 34Wet 20 23 / 21 27 / 25

Standing Water/ Slush 14 16 19

Snow – No melting ** 18 21 / 19 26 / 24

Ice – No Melting 7 7 8


Recommended Takeoff Crosswind Guidelines and Runway Width Recommended Takeoff Crosswind Guidelines and Runway Width

The Recommended Takeoff Crosswind guidelines were originally developed for “standard” (typically 45m) runway widths, but recent analysis validates application of these wind guidelines down to the following minimum runway widths:

The Recommended Takeoff Crosswind guidelines were originally developed for “standard” (typically 45m) runway widths, but recent analysis validates application of these wind guidelines down to the following minimum runway widths:

Model Minimum Runway Width with published Takeoff Crosswinds

737* 30m757 30m767 35m777 40m747 40m

Reduced crosswind guidelines are recommended for takeoff on runways narrower than the above minimum widths.

*737-500 may require aft CG curtailment at 30m runway width


Recommended Landing Crosswind Guidelines and Runway Width Recommended Landing Crosswind Guidelines and Runway Width

The Recommended Landing Crosswind guidelines were originally developed for “standard” (typically 45m) runway widths, but recent analysis validates application of these wind guidelines down to the following minimum runway widths:

The Recommended Landing Crosswind guidelines were originally developed for “standard” (typically 45m) runway widths, but recent analysis validates application of these wind guidelines down to the following minimum runway widths:

Model Minimum Runway Width with published Landing Crosswinds

737 30m757 33m767 35m777 37m747 37m

Reduced crosswind guidelines are recommended for landing on runways narrower than the above minimum widths.


Summary:Operational RecommendationsSummary:Operational Recommendations

● Adjust VMCG (and associated minimum field length) appropriately for narrow runway

● Adjust recommended crosswind guidelines appropriately for narrow runway

● Use reduced takeoff thrust (when performance permits) to minimize thrust asymmetry following engine failure.

● Load to more forward CG to improve directional control.

● Address narrow runway appropriately in MEL.

● Adjust VMCG (and associated minimum field length) appropriately for narrow runway

● Adjust recommended crosswind guidelines appropriately for narrow runway

● Use reduced takeoff thrust (when performance permits) to minimize thrust asymmetry following engine failure.

● Load to more forward CG to improve directional control.

● Address narrow runway appropriately in MEL.


Summary:Flight Crew RecommendationsSummary:Flight Crew Recommendations

● Provide dedicated training and qualification for narrow runway operations (properly validated simulator can be very effective device for this).

● Be vigilant for and aggressive in responding to asymmetric spin-up or engine failure on takeoff roll.

● Be aware that differential braking may be required for RTO below 65 knots.

● Exercise conservative judgment with respect to approach and landing, especially in adverse weather

● Provide dedicated training and qualification for narrow runway operations (properly validated simulator can be very effective device for this).

● Be vigilant for and aggressive in responding to asymmetric spin-up or engine failure on takeoff roll.

● Be aware that differential braking may be required for RTO below 65 knots.

● Exercise conservative judgment with respect to approach and landing, especially in adverse weather


Summary:Regulatory DevelopmentsSummary:Regulatory Developments

● Discussions continue in various regulatory working group forums on narrow runway operations

● Some manufacturers publish generic guidance in AFM (although little formal regulatory guidance currently exists)

● Boeing provides specific advisory recommendations upon request

● Individual airport and runway characteristics should still be considered

● Discussions continue in various regulatory working group forums on narrow runway operations

● Some manufacturers publish generic guidance in AFM (although little formal regulatory guidance currently exists)

● Boeing provides specific advisory recommendations upon request

● Individual airport and runway characteristics should still be considered


Questions?Questions?

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