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
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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:

• Inadequate pilot training for recognition of a situation in which the speedbrakes do not automatically deploy as expected after landing. As stated above, the incident pilots did not recognize that the speedbrakes had not automatically deployed after touchdown. This report cites three other events in which the pilots were distracted and did not ensure deployment of the speedbrakes. Prompt speedbrake deployment after touchdown and monitoring of the speedbrake system during the landing roll is especially critical for increased braking effectiveness when landing on short and/or contaminated runways.
• Lack of an alert to warn pilots when speedbrakes have not automatically deployed during the landing roll. Although American Airlines had a company requirement for a callout confirming automatic speedbrake deployment after touchdown, the pilots still became distracted from ensuring that the speedbrakes deployed properly. A clearly distinguishable and intelligible alarm would help bring the monitoring pilot's attention back to the speedbrakes and enable him to manually deploy them in case they do not automatically deploy.
• Lack of guidance for pilots of certain Boeing airplanes to follow when an unintended thrust reverser lockout occurs. Because of the lockout condition that was created in the thrust reverser system during the incident landing, the flight crew needed to stow the reverse thrust lever to unlock the system before attempting to redeploy the thrust reversers. However, postincident interviews with American Airlines pilots indicated that company pilots were not aware of this technique, and moving the reverse thrust levers to the stow position during the landing roll would not be an intuitive action.
• Lack of pilot training for multiple emergency and abnormal situations. About the time that the speedbrakes did not deploy, the thrust reverser system also did not deploy. In this incident, the pilots encountered an abnormal situation when both the speedbrake and thrust reverser systems did not deploy as expected. Although the pilots were not aware of the specific solution to the thrust reverser abnormality, the pilots were aware that they could manually deploy the speedbrakes at any time. However, because of the pilots' focus on and efforts to resolve the thrust reverser anomaly, neither pilot noticed the abnormal speedbrake situation until the airplane had come to a stop off the end of the runway. If the incident pilots had received training on the handling of multiple emergency or abnormal situations, they might not have focused exclusively on the thrust reverser nondeployment and may have recognized the speedbrake nondeployment earlier.
• Lack of pilot training emphasizing monitoring skills and workload management. After the first officer attempted to deploy the thrust reversers, the captain took command of the reverse thrust levers. By doing this, the captain deviated from normal company procedures regarding the pilot flying/pilot monitoring responsibilities during the landing roll. If the captain had adhered to his monitoring responsibilities during the landing roll, it is more likely that he would have recognized that the speedbrakes had not automatically deployed and corrected the situation by manually deploying them.

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

Recommendations

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)