What happened
On the evening of 07 September 2023, a ground testing operation was underway at Gray Butte Airfield, California, to evaluate electromagnetic interference and compatibility (EMI/EMC) following a new software upload to an MQ-9A, tail number 12-4209. The mission was being conducted by contractors supporting the Air Force Life Cycle Management Center (AFLCMC) Detachment 3.
Following a mid-shift meal, the test team restarted the aircraft engine to proceed with the second phase of testing. A civilian contractor employed as a test engineer approached the rear of the right wing at weapons station 6 to take telemetry readings using an RF power meter. While attempting to move toward the left wing by walking behind the aircraft, the engineer walked directly into the spinning propeller, sustaining fatal injuries.
The investigation
The investigation examined the procedures used during the ground test and the training provided to personnel. Investigators reviewed various safety diagrams regarding propeller-free zones, noting significant discrepancies between AFLCMC Det 3 training, General Atomics briefings, and standard maintenance technical orders. The board also scrutinized the use of an unfamiliar RF power meter that required frequent user interaction to maintain screen visibility.
Furthermore, the investigation looked into the communication protocols between the test engineer and ground support personnel, as well as the operational pressure placed on the team due to previous schedule delays.