Report | Nov. 4, 2020

Audit of the Department of the Navy Actions Taken to Improve Safety and Reduce Physiological Events (DODIG-2021-004)


Publicly Released: November 6, 2020



The objective of this audit was to determine to what extent the Department of the Navy (DON) performed research, training, maintenance, upgrades, and testing on fixed‑wing aircraft to improve safety and reduce physiological events (PEs).


A PE occurs when an aircrew member experiences physiological symptoms, and the symptoms are directly attributable to a known or suspected aircraft or aircrew systems malfunction. The DON experienced an increase from 13 PEs in FY 2010 to 165 PEs in FY 2017. As a result, Congress has expressed an increased interest in the DON’s efforts to reduce PEs.

During this audit we reviewed the DON’s actions taken to reduce PEs in the T‑45 (Goshawk), F/A‑18 A‑D (Legacy Hornets), F/A‑18 E/F (Super Hornets), and EA‑18G (Growler). We chose these aircraft because they are the trainer and fighter aircraft that reported the highest average number of PEs per 100,000 flight hours from FYs 2010 to 2019.



The DON has taken actions to improve overall safety and reduce PEs for the eight aircraft we reviewed. The DON performed research, training, maintenance, upgrades, and testing with the goal of improving safety and reducing PEs. Specifically, the DON:

• performed research on aircrew breathing equipment (such as masks), on air quality, and on   
   in‑flight physiological monitors;

• trained aircrew members on PE causes, symptoms, prevention, and emergency procedures;

• performed maintenance and upgraded aircraft components to ensure system maintenance
   and functionality on Goshawks;

• established system component life limits, inspected and replaced system components, and
   planned to upgrade an aircraft component on Legacy Hornets, Super Hornets, and Growlers;

• tested in‑flight physiological monitors and conducted test flights with aircrew members
   wearing monitors that collected data on potential causes of PEs.

Through this research, training, maintenance, upgrading, and testing, the DON has taken actions to reduce, mitigate, and identify causes for PEs related to the Goshawks, Legacy Hornets, Super Hornets, and Growlers. The DON has implemented 189 recommendations from the Goshawk, Legacy Hornet, Super Hornet, and Growler Root Cause Corrective Action teams and has ongoing plans to implement an additional 250 recommendations. By implementing the recommendations and other DON initiatives, the DON has achieved consistent year‑to‑year reductions from FYs 2017 through 2020 in the PE rate per 100,000 flight hours for two of the aircraft in our review. For five aircraft the DON achieved a reduction in the PE rate in FY 2020 when compared to FY 2017. For the remaining aircraft, the DON had no PEs from FYs 2017 through 2020.

In addition, the DON’s completed and ongoing research, testing, and development of solutions to gather data in real time on both the physiology of the aircrew members and the environmental conditions within the aircraft will improve the DON’s ability to identify PEs and determine potential root causes.

Finally, the DON will never completely eliminate PEs because they can be caused by malfunctioning aircraft components and human factors such as dehydration. However, the actions taken thus far have eliminated potential causes of PEs related to aircraft systems, air contamination, and flight gear fit. Furthermore, ongoing and planned actions are comprehensive and address potential areas for the DON to identify the root causes of PEs and improve safety for the aircrew members.


This report is the product of Proj. No. D2019-D000RK-0212.000