Event Sequence
During the climb, the captain (pilot in command) increased pitch. A flight attendant entered the cockpit and suggested a faster climb so she could begin cabin service. The autoflight system was set in pitch and heading modes, contrary to company policy. The captain and flight attendant engaged in non-pertinent conversation for 4.5 minutes while the first officer was making log entries.
The airplane stalled in instrument meteorological conditions (IMC) at 17,400 feet. Initial recovery began at 6,700 feet after the first officer lowered the landing gear. Due to improper recovery actions, a second stall occurred, with recovery at 5,500 feet.
Damage and Forced Landing
During the events, the left propeller shed three blades, and the left engine cowling separated. The left engine was shut down during the descent. Level flight could not be maintained, and a forced landing was made at a closed airport. The captain overshot the final turn due to controllability problems and landed fast with 1,880 feet of wet runway remaining. The airplane hydroplaned off the runway and sustained further damage.
Weather and Crew Rest
The freezing level was near 11,500 feet. Cloud tops were at 21,000 feet with potential for icing up to 19,000 feet. The crew had limited sleep during the three-day trip, although rest periods were available.
No pre-accident malfunction was found.
Probable Cause
The official probable cause is: the captain's failure to maintain professional cockpit discipline, his consequent inattention to flight instruments and ice accretion, and his selection of an improper autoflight vertical mode, all of which led to an aerodynamic stall, loss of control, and a forced landing. Factors contributing to the accident were: poor crew discipline, including flightcrew coordination before the stall and the flightcrew's inappropriate actions to recover from the loss of control. Also contributing to the accident was fatigue induced by the flightcrew's failure to properly manage provided rest periods.