Accident Overview
An emergency medical service (EMS/medevac) flight transporting a maternity patient from Flagstaff to Phoenix crashed during the arrival phase. The pilot was conducting a VOR-A approach in instrument meteorological conditions (IMC) at night when he reported an avionics problem and initiated a missed approach. During the missed approach, he stated that he had 'lost' an inverter and that the gyros were inoperative. Radar vectors were being provided when the pilot transmitted 'we have big trouble here.' Shortly thereafter, radar and radio contact were lost, and the aircraft crashed approximately 7 miles southeast of the airport.
Impact and Wreckage
The impact crater was deep, and the aircraft was demolished. No preimpact engine or airframe failure was found during the investigation.
Maintenance and Operational History
Investigators determined that the #2 (copilot's) attitude indicator was inoperative on the previous flight. A discrepancy report was submitted to the avionics department, but the requested entry was not made in the aircraft's form-4 maintenance records. The pilot departed before corrective action was taken. The operations manual required 1,000 hours of multi-engine time as pilot-in-command and training by designated instructor pilots. The pilot had approximately 837 hours of multi-engine time, recorded 9 training flights in N6858S with non-designated instructors, and completed a Part 135 flight check on February 17, 1988. Both the pilot and the flight nurse were killed in the crash.
Findings
Maintenance and Procedures
- Improper recordkeeping and failure to follow procedures were noted.
- Inadequate surveillance of operations by company/operator management was identified.
Electrical System
- The cause of the electrical system failure was undetermined.
- The inverter was inoperative.
- The attitude indicator was inoperative.
Loss of Control
- The pilot did not maintain aircraft control.
- The pilot experienced spatial disorientation.
- Contributing factors included dark night conditions, low ceiling, and snow, as well as the pilot's lack of total experience in the aircraft type.
Collision with Terrain
- The aircraft descended uncontrolled and collided with terrain.