American Airlines flight AA2253 : 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. The National Transportation Safety Board determines that the probable cause of this incident was a manufacturing defect in a clutch mechanism that prevented the speed brakes 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 speed brake 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.
“ah ladies and gentlemen captain speaking …we’re not sure what ah happened we’re not sure if the braking didn’t work. looked like it was but our reversers did not work so ah we’re not sure what happened here“.
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 speed brake 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 non deployment.