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MQ-9A Accident Report Released

  • Published
  • Air Force Materiel Command

An Air Force Materiel Command Accident Investigation Board has identified the cause of an MQ-9A mishap which fatally injured a civilian contract employee during a ground developmental test event at Gray Butte Airfield, California, on Sept. 7, 2023.

Stephanie R. Cosme, 32, of Palmdale, California was struck and critically injured the evening of Sept. 7 when she inadvertently walked into the parked remotely piloted aircraft’s rotating propeller. She died shortly after being airlifted to Antelope Valley Hospital in Lancaster. Cosme was employed by Sumaria Systems, LLC, providing test support services for the Air Force Life Cycle Management Center, Detachment 3.

In his statement of opinion, the Accident Investigation Board president found two causes for the mishap: first, the test engineer was incorrectly instructed or trained on how to take telemetry readings when approaching the MQ-9A while the engine was running. Second, she lost situational awareness while walking around the mishap aircraft taking telemetry readings with a hand-held measurement device.

The AIB President, Brig. Gen. Lance R. French, also identified two factors which substantially contributed to the mishap. There was a clear lack of communication among the contractor test team and ground support personnel. Additionally, due to previous delays and cancellations, the tests conducted on Sept. 7 were rushed. 

Gray Butte Airfield is owned and operated by General Atomics and located near Edwards AFB. At the time of the mishap, the Sumaria Systems contractor team was providing engineering and professional test support to evaluate electromagnetic interference/electromagnetic compatibility testing with a new release of MQ-9A software on payloads and other aircraft systems. The mishap contract employee, aircraft crew chief and maintainers, as well as the test director, mishap pilot and sensor operator in the nearby ground station, were civilian contractors. 

The AIB report identified a replication of the mishap sequence with an MQ-9 parked in the same spot with the engine running at the same power setting, similar twilight lighting conditions and airfield ramp stadium lighting that were present on Sept. 7. In the simulation, the spinning propeller was not visible when looking to the rear of the aircraft, from where the contract employee approached.

The AFLCMC Intelligence Surveillance and Reconnaissance/Special Operations Forces Directorate at Wright-Patterson Air Force Base, Ohio, oversees lifecycle program management for the MQ-9A Reaper fleet.

The AIB report is available at