Accident Summary
During a night instrument approach to Gulkana Airport, radio contact with the flight was lost. The wreckage was subsequently located 7.4 miles north of the terminal VOR on the 330° radial. The inbound course for the VOR runway 14 approach was on the 315° radial. An on-scene examination determined that the aircraft was tracking inbound when it collided with trees, crashed, and burned approximately 2.4 miles before reaching the final approach fix.
Aircraft and Crew Information
The captain and first officer were qualified to fly both Learjet and DHC-7 aircraft. This was the captain's first day back after a vacation of about 1.5 weeks in Hawaii. The first officer had an adequate rest period before reporting for duty but had previously worked a varied schedule. The operator had been shifting pilots between 14 CFR 135 and 14 CFR 121 rest/duty requirements.
Findings
Both engines were operating at impact and had ingested considerable tree material. No evidence of preimpact mechanical failure was found. Weather conditions included rain, and the accident occurred during dark night. The flight was on an IFR approach. The investigation found that the pilot in command performed an improper IFR procedure, and the copilot failed to attain remedial action. Fatigue due to circadian rhythm disruption in the copilot and flight schedule management by the company were also noted.
Probable Cause
The official probable cause is: Occurrence #1: in flight collision with object. Phase of operation: approach - IAF to FAF/outer marker (IFR). Findings: 1. (f) weather condition - rain; 2. (f) light condition - dark night; 3. (c) IFR procedure - improper - pilot in command; 4. (c) remedial action - not attained - copilot/second pilot; 5. (f) fatigue (circadian rhythm) - copilot/second pilot; 6. (f) fatigue (flight schedule) - company/operator management; 7. (f) object - tree(s); 8. (c) minimum descent altitude - not maintained. Occurrence #2: in flight collision with terrain/water. Phase of operation: descent - uncontrolled.
All three occupants were killed.