Poor airspeed control led to an aerodynamic stall that caused an Empire Airlines ATR 42 to crash while landing at Lubbock, Texas, two years ago.
US National Transportation Safety Board investigators said that poor crew resource management, flawed decision-making and fatigue were contributing factors in the accident, which left the captain with serious injuries, the first officer with minor injuries and the FedEx Express-registered aircraft substantially damaged.
Empire flight 8284 had departed Fort Worth on the morning of 27 January 2009 and was conducting an instrument approach to Lubbock at 04:37 when it crashed short of Runway 17R.
Poor airspeed control led to an aerodynamic stall that caused an Empire Airlines ATR 42 to crash while landing at Lubbock, Texas
The aircraft had accumulated ice during the flight, but the NTSB noted that it "could have landed safely" had the airspeed been maintained.
The NTSB said that, during the approach into Lubbock, at about 1,400ft (425m) above the ground and 90s from the runway, the captain indicated a flight-control problem saying: "We have no flaps."
It adds: "Although the crew members 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 [aircraft]."
Neither pilot "adequately monitored" the airspeed from that point forward, which ultimately resulted in a stick-shaker activation.
"The captain continued the unstabilised approach, even though he received additional stick-shaker activations and an aural 'pull up' warning from the terrain awareness and warning system," said the NTSB. At this point the turboprop was descending at more than 2,000ft/min.
The captain applied maximum power 17s after the pull-up warning, after which the aircraft entered an aerodynamic stall and crashed, said the NTSB.
Nine safety recommendations issued by investigators include a direction to improve crew-resource-management training to "encourage first officers to more assertively voice their concerns" and also to "teach captains to develop a leadership style that supports first-officer assertiveness".
In its findings, the NTSB says operators should be prohibit dispatch of pneumatic boot-equipped aircraft into icing conditions outside those for which the aircraft has been certificated, while ATR 42s should also be equipped with flap-asymmetry annunciator lights.
It also recommends improving flight-simulator fidelity to "more accurately model aerodynamic degradations resulting from airframe ice accumulation".