National Transportation Safety Board
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The crash of a twin turboprop cargo airplane while on approach to landing at Lubbock, Texas, was caused by the flight crew's failure to maintain a safe airspeed, which put the plane into an aerodynamic stall at an altitude too low from which to recover, the NTSB determined today.
Poor crew resource management, flawed decision-making and human fatigue were cited as contributing factors to the crash that left the captain seriously injured and the first officer with minor injuries.
On January 27, 2009, at 4:37 a.m. CST, an ATR 42-320(N902FX) operating as Empire Airlines flight 8284 between Ft. Worth and Lubbock, was on an instrument approach when it crashed short of the runway. The airplane, which was registered to Federal Express Corporation (FedEx) and operated by Empire Airlines, Inc., was substantially damaged.
The aircraft, which had departed Ft. Worth about 84 minutes before the accident occurred, encountered icing conditions while en route to Lubbock. And although the airplane accumulated some ice during the flight that degraded its performance, the NTSB determined that the aircraft could have landed safely had the airspeed been maintained.
During the approach into Lubbock, at about 1400 feet above the ground and about 90 seconds from the runway, the captain indicated a flight control problem saying, "We have no flaps." Although the crewmembers had been trained to perform a go-around and refer to a checklist if a flap problem occurred during an approach, the captain chose to continue the approach as he attempted to troubleshoot the flap anomaly while the first officer flew the plane. Neither flight crewmember adequately monitored the airspeed, which decayed to the extent that the stick shaker activated, which warned of an impending aerodynamic stall.
The captain continued the unstabilized approach even though he received additional stick shaker activations and an aural "pull up" warning from the terrain awareness and warning system (TAWS). At that point, the plane was descending at a rate of over 2,000 ft per minute.
Although procedures for responding to either the stick shaker or the TAWS warning require the immediate application of maximum engine power, the captain did not apply maximum power until 17 seconds after the TAWS warning. Seconds after maximum power was applied, the airplane entered an aerodynamic stall and crashed.
"We know that flight crews can find themselves in dynamic situations, like the one in this accident, where they have to make rapid decisions often within seconds, said NTSB Chairman Deborah A.P. Hersman. "These high workload and high stress situations often manifest at the end of long days, long nights or in bad weather, which is why following established procedures and using good crew resource management is critical."
The NTSB also uncovered significant issues related to icing. Empire Airlines had dispatched the airplane into icing conditions that were outside the airplane's certification envelope. Although this practice was not prohibited by the Federal Aviation Administration (FAA), the NTSB has longstanding concerns about operations in freezing drizzle/freezing rain and as a result of this investigation made a safety recommendation to address the issue.
Among the nine safety recommendations that the NTSB made to the FAA were: improve crew resource management training to encourage first officers to more assertively voice their concerns and teach captains to develop a leadership style that supports first officer assertiveness; prohibit operators of pneumatic boot-equipped airplanes from dispatching them into icing conditions that are outside of those that the airplane was certified for; educate pilots and dispatch personnel on the dangers of flight in freezing precipitation; develop a method to quickly communicate flight information regarding the number of persons aboard and the presence of hazardous materials to emergency responders; provide guidance on monitoring and ensuring the operability of emergency response and mutual aid gates during winter operations; require all operators of ATR 42 and ATR 72 series airplanes to be equipped with an aircraft performance monitoring system; improve flight simulator fidelity to more accurately model aerodynamic degradations resulting from airframe ice accumulation and ensure that flight crews are trained on them; and require all ATR 42 aircraft to be equipped with a flap asymmetry annunciator light.
A synopsis of the NTSB report, including the probable cause, conclusions, and safety recommendations is available at http://go.usa.gov/b4X.
The NTSB's full report will be available on the website in several weeks.
The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.