Report | Aug. 31, 2021

Audit of the Department of the Air Force’s Actions Taken to Mitigate Physiological Events (DODIG-2021-120)


Publicly Released: September 2, 2021



The objective of this audit is to determine whether the Department of the Air Force implemented corrective actions on fixed‐ wing aircraft to improve safety by reducing physiological events.



A physiological event (PE) is any injury, illness, or abnormal physiological condition experienced by aircrew or others because of the flight environment. During this audit, we reviewed the Air Force’s actions taken to reduce PEs in the T‑6A Texan II, F‑15C Eagle, F‑15D Eagle, and F‑15E Strike Eagle aircraft. We selected fighter aircraft and trainer aircraft with the highest pilot‑reported rate of PEs. The fighter aircraft with the highest rate of pilot‑reported PEs was the F‑15E Strike Eagle. The trainer aircraft with the highest rate of pilot‑reported PEs was the T‑6A Texan II. We included the F‑15C Eagle and F‑15D Eagle in our audit scope because the same system program office manages the F‑15E Strike Eagle, F‑15C Eagle, and F‑15D Eagle.



The Air Force has implemented corrective and preventative actions to improve safety and reduce PEs for the aircraft we reviewed—the T‑6A Texan II, F‑15C Eagle, F‑15D Eagle, and F‑15E Strike Eagle. Specifically as of March 22, 2021, the Air Force:

  • closed 47 of 79 recommendations resulting from Air Force investigations of mishaps to address safety and reduce PEs in the four aircraft;
  • conducted 67 research studies since FY 2010 on Air Force aircraft and aircrew breathing systems in an effort to identify the causes and reduce the rates of PEs experienced by aircrew;
  • was researching and updating the military standard that will contain design criteria for aircrew breathing systems, which the Director of the Air Force Physiological Episode Action Team stated should decrease the possibility of PEs for future acquisitions of aircrew breathing systems;
  • modified aircraft maintenance procedures and upgraded and modified aircraft to improve safety, minimize the number of PEs, and react to PEs while implementing recommendations; and
  • provided aircrew training that included identifying potential PE causes, symptoms, prevention, and emergency procedures.

While the Air Force has taken actions to address potential causes of PEs, according to Air Force officials it cannot completely eliminate PEs caused by unanticipated aircraft malfunctions or human factors. Ongoing and planned actions by the Air Force are comprehensive and address potential areas to mitigate PEs.


This report is the result of Proj. No. D2020-D000RL-0167.000.