Fatal Mountain Strike During Low-Altitude Military Flight (55-4539)

A military aircraft struck Mt Vasquez Peak after entering a box canyon with insufficient altitude. All nine occupants were killed. The pilot's decision to enter the canyon in violation of regulations was the probable cause.

Probable cause

The accident was determined to be the consequence of a wrong decision by the pilot, who violated paragraph 12A (4) of AF Reg 60-16 by entering a box canyon with insufficient altitude and lateral clearance to effect a safe recovery. Contributing factors included a breach of air discipline, as the pilot operated the aircraft for 32 miles at altitudes ranging from 500 feet down to 50 feet above the immediate terrain, in violation of paragraph 12A (3) of AF Reg 60-16. Weather conditions may have also contributed, as forecast winds and turbulence indicated a probable adverse mountain wave effect on the aircraft immediately prior to impact.