The Flight
A Part 135 on-demand air taxi flight departed Denver, Colorado, with a destination of Columbus, Nebraska. Weather forecasts indicated icing conditions along the entire route. During the flight, air traffic control (ATC) advised the pilot of reported icing ahead. The pilot was cleared to climb to 19,000 feet to get above the clouds.
Sequence of Events
The pilot reported alternator problems and requested a diversion to North Platte, Nebraska. He then elected to divert to McCook, Nebraska, due to weather conditions at North Platte. ATC lost communication with the pilot during the diversion.
Witness Observations
Witnesses reported that the airplane circled the McCook Airport twice. During the second circle, the airplane entered a bank of about 45 degrees and then stalled. It subsequently traveled approximately 190 feet through a stand of trees before coming to rest. Witnesses noted that the airplane was covered with ice, and a piece of windshield was found with one-half inch of mixed ice.
Investigation Findings
Examination revealed that both alternators had one phase in the stator winding shorted. The investigation determined that the accumulation of airframe ice and the pilot's in-flight planning/decision were causal factors.