By John DeLisi
Director of Office of Aviation Safety
For the 179 passengers aboard American Airlines Flight 2253, the worst that happened on Dec. 29, 2010 was a frightening landing and disembarking into deep snow after their airplane overran the runway at Jackson Hole, Wyo. The Boeing 757 they were traveling in suffered two rare mechanical failures during a stormy landing on a short runway. But the airplane stopped, only slightly damaged, 730 feet beyond the pavement. All were safe.
Still, the NTSB sent a team of investigators to the scene and spent more than a year studying the incident to learn what happened and why. On June 5, the Board issued its determination of probable cause and made safety improvement recommendations. http://www.ntsb.gov/news/2012/120605c.html
Of course, the landing could have turned horrific. The airplane’s speedbrakes failed to automatically deploy and there was a lengthy delay in engaging the thrust reversers. But the fact that there were no fatalities — no twisted and charred metal, no fiery hole in the ground — does not make the incident of less importance to safety investigators. Our job at the Safety Board is to try to prevent accidents by learning from mistakes.
Mechanical failures aside, there were lessons to be learned about how humans interact with increasingly complex, yet remarkably dependable, airplanes. When the plane touched down, the captain erroneously announced that the speedbrakes had deployed. Was he operating on observation or expectation, based on his experience with many hundreds of landings where the speedbrakes deployed flawlessly? And when the thrust reversers locked up — the result of a rare mechanical/hydraulic interaction — both pilots focused exclusively on the thrust reverser problem, even though manually deploying the speedbrakes would have safely stopped the airplane without the use of the reversers.
They failed to properly monitor the situation, which in today’s aircraft is as important a skill as being a good stick-and-rudder pilot. And they failed to manage the tremendous cockpit workload during those precious seconds the airplane was racing toward the end of the runway.
To assist pilots in the future, we’ve recommended that they be provided training for speedbrake failures and that manufacturers add a landing configuration warning in the cockpit.
These were not inexperienced or unprofessional pilots. They prepared well for what they knew was going to be a challenging landing. But did they prepare enough for the unexpected? Did they take for granted the incredible reliability of the incredible machines they fly? Perhaps that is the greatest lesson to be learned from American Airlines Flight 2253.