Investigation Summary
During the takeoff roll, the aircraft was subjected to intense mountain wave conditions. While the tower reported winds of 27 knots, a sensor at the runway's end recorded crosswinds of 40 knots, with post-accident analysis identifying a peak gust of 45 knots. As the aircraft reached approximately 87 to 90 knots, it began to veer left. The captain initially applied right rudder to compensate but then ceased the input four seconds before the aircraft left the runway. In a desperate attempt to regain control as the aircraft approached the runway edge, the captain briefly used the nosewheel steering tiller for a second or two, but this was ineffective at high speed. The captain later testified that he believed the rudder had stopped working or that the aircraft had hit a patch of ice. The NTSB found no evidence of mechanical failure in the rudder system or landing gear. The investigation highlighted that the industry-standard pilot training did not prepare crews for such extreme gusts, leading the captain to abandon the primary control needed to counteract the weather-induced excursion.
Final Conclusions
The NTSB published its final report on July 13, 2010, citing the probable cause as the captain's cessation of right rudder input about four seconds before the excursion. Contributing factors included inadequate crosswind training for extreme gusts and the lack of a requirement for air traffic control to provide pilots with real-time, localized wind information rather than averages.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Former Navy pilot; described as a 'by the book' captain.
First Officer
Systems & Failure Modes
Rudder Control System
The primary flight control used to maintain directional stability on the ground; investigators confirmed the system was fully functional despite the captain's perception that it had failed.
Low Level Windshear Alert System (LLWAS)
A system of sensors used to detect wind changes; the investigation found that specific high-wind data from individual sensors was not required to be relayed to pilots.
Interesting Facts
- 01The aircraft was hit by a peak crosswind gust of 45 knots, which was significantly higher than the 27 knots reported by the tower.
- 02The Boeing 737-500 has a demonstrated crosswind takeoff limitation of 33 knots on a dry runway.
- 03An off-duty pilot, Richard Lowe, assisted in the evacuation and was later awarded the Airman's Medal.
- 04The aircraft's fuselage cracked behind the wings and the right engine caught fire, melting overhead bins onto the seats.
- 05NTSB analysis of 250,327 Boeing 737-500 departures found only 0.002% occurred in crosswinds above 30 knots.
Safety Actions & Advisories
Crosswind Training Revision
The FAA required the airline industry to adjust crosswind training protocols to include more extreme wind gust scenarios.
ATC Wind Reporting Procedures
Air traffic controllers are now required to provide multiple sources of wind information and peak gust data rather than just averages when conditions are hazardous.