Accident Details
On a local test flight from Oklahoma City-Wiley Post Airport, the crew reached cruising altitude before the airplane disappeared from radar screens. It then dove into the ground, crashing in an open field. Debris scattered over a wide area, and both occupants were killed.
Probable Cause
The official investigation determined that the aircraft suffered an explosive decompression in flight following an incorrect use of equipment on part of the crew. The following factors were reported: electrical system switches, pressurization control and indicating system, lack of familiarity with the aircraft, failure to use or incorrect use of miscellaneous equipment, inadequate supervision of flight, the copilot selecting an uncovered pressurization dump switch, and different panel position on the 690 model.