Aircraft Accident Report

Runway Overrun American Airlines Flight 2253 Boeing 757-200, N668AA

Jackson Hole, Wyoming
December 29, 2010

NTSB Number: AAR-12-01
NTIS Number: PB2012-910401
Adopted: June 18, 2012

Executive Summary

This report discusses the December 29, 2010, incident involving American Airlines flight 2253, a Boeing 757-200, N668AA, which ran off the departure end of runway 19 and came to a stop in deep snow after landing at Jackson Hole Airport (JAC), Jackson Hole, Wyoming. The occupants were not injured, and the airplane sustained minor damage.

Probable Cause

The National Transportation Safety Board determines that the probable cause of this incident was a manufacturing defect in a clutch mechanism that prevented the speedbrakes from automatically deploying after touchdown and the captain's failure to monitor and extend the speedbrakes manually. Also causal was the failure of the thrust reversers to deploy when initially commanded. Contributing to the incident was the captain's failure to confirm speedbrake extension before announcing their deployment and his distraction caused by the thrust reversers' failure to initially deploy after landing.

This report addresses increased pilot awareness of and focus on speedbrake and thrust reverser deployment during landing. The incident pilots were familiar with winter operations at JAC and thoroughly assessed the pertinent weather, airport, and airplane performance information while en route to JAC. The pilots determined that they could land safely at JAC using normal deceleration procedures (thrust reversers, speedbrakes, and wheel brakes). However, the precise timing of the unloading of the main landing gear just after touchdown that coincided with the deployment of the thrust reversers resulted in a rare mechanical/hydraulic interaction in the thrust reverser system, and the thrust reversers were locked in transit instead of continuing to deploy. Further, an unrelated defect in the automatic speedbrake mechanism prevented the speedbrakes from automatically deploying. Although the pilots could have manually deployed the speedbrakes at any time during the landing roll, neither pilot recognized that the speedbrakes had not automatically deployed (as selected) because they were both distracted by, confused by, and trying to resolve the thrust reverser nondeployment.

Safety issues identified in this incident include the following:

As a result of this investigation, three new safety recommendations are issued and three existing safety recommendations are reiterated to the Federal Aviation Administration.


New Recommendations

The National Transportation Safety Board makes the following recommendations to the Federal Aviation Administration:

Require all operators of existing speedbrake-equipped transport-category airplanes to develop and incorporate training to specifically address recognition of a situation in which the speedbrakes do not deploy as expected after landing. (A-12-44)

Require all newly type-certificated 14 Code of Federal Regulations Part 25 airplanes to have a clearly distinguishable and intelligible alert that warns pilots when the speedbrakes have not deployed during the landing roll. (A-12-45)

Require Boeing to establish guidance for pilots of all relevant airplanes to follow when an unintended thrust reverser lockout occurs and to provide that guidance to all operators of those airplanes. (A-12-46)

Previous Recommendations Reiterated in this Report

In addition, the National Transportation Safety Board reiterates the following recommendations to the Federal Aviation Administration:

Establish best practices for conducting both single and multiple emergency and abnormal situations training. (A-09-24)

Once the best practices for both single and multiple emergency and abnormal situations training asked for in Safety Recommendation A-09-24 have been established, require that these best practices be incorporated into all operators' approved training programs. (A-09-25)

Require that all pilot training programs be modified to contain modules that teach and emphasize monitoring skills and workload management and include opportunities to practice and demonstrate proficiency in these areas. (A-07-13)