NTSB Faults Mechanical Defect, Training and Pilots in 757 Accident
No passengers were injured when an American Airlines Boeing 757 ran off the end of Runway 19 at Jackson Hole Airport (JAC]), Jackson Hole, Wyo., in December 2010, but a number of safety issues highlighted in the NTSB report make the event worth reviewing.
In its recently released report, the Safety Board said the probable cause for the incident was a manufacturing defect in a clutch mechanism that prevented the speed brakes from automatically deploying after touchdown. The captain, however, failed to monitor the situation and extend the speed brakes manually. The thrust reversers also failed to deploy when initially commanded. Contributing to the incident was the captain’s failure to confirm extension of the speed brakes before announcing their deployment, and his distraction caused by the thrust reversers’ failure to initially deploy.
The NTSB said there was also, “inadequate pilot training for recognition of a situation in which the speed brakes do not automatically deploy as expected after landing. The pilots did not recognize that the speed brakes had not automatically deployed after touchdown.” The report cites three other events in which the pilots were distracted and did not ensure deployment of the speed brakes.
The Boeing aircraft also lacked an alert system to warn pilots when the speed brakes were not automatically deployed during the landing roll. Although American Airlines had a company requirement for a callout confirming automatic speed-brake deployment after touchdown, the pilots still became distracted from ensuring that the speed brakes deployed properly.
The report also said there was a lack of guidance for pilots of certain Boeing airplanes when an unintended thrust-reverser lockout occurred. Because of the thrust-reverser lockout created 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, post-incident interviews with the American Airlines pilots indicated they 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 for them.