Introduction
An aircraft entered an area of forecast moderate icing while its ice detection system was intermittently inoperative. While holding in icing conditions to check flight inspection equipment, the crew noted ice accretion and activated the surface de-ice system. Ice subsequently broke loose and entered the engine intakes, causing both engines to flame out.
Sequence of Events
During the emergency descent, the crew initially attempted restarts, but neither engine would sustain power. The crew requested vectors to a more distant airport. The aircraft subsequently collided with trees.
Pilot Background
Both pilots were seen drinking the previous night. The captain had decided to retire that day. The copilot had recently lost his driver's license for DUI, had worked in flight operations only 3 days in the previous 8 weeks, and had limited training in flight inspection. Both pilots had personal stresses which may have influenced performance. Toxicological examination of the captain's contaminated thoracic blood revealed 0.057% alcohol, though putrefaction would have accentuated part of that level. The copilot had trace alcohol in urine only.
Investigation Findings
Examination of both engines showed compressor foreign object damage (FOD) consistent with ice ingestion. No other aircraft system or engine malfunctions were found. The investigation identified that the pilot in command was inattentive, delaying ice removal, and the copilot had inadequate initial training. The FAA was cited for inadequate surveillance and insufficient staff.
Probable Cause
The official probable cause is: Failure of the pilot in command to observe the rapid accretion of ice on the airplane due to his attention being diverted.