In-Flight Hypoxia Events in Tactical Jet Aviation: Characteristics Compared to Normobaric Training

Abstract

Hypoxia continues to be a significant threat in military aviation. In an attempt to counter the hypoxia threat, military jet aviators receive periodic training using a reduced oxygen breathing device (ROBD). This study explored the characteristics of in-flight hypoxia events among tactical jet aviators and compared reported symptoms to those experienced during ROBD training. An anonymous survey was administered to naval aviators prior to aviation physiology training. The survey queried them about previous in-flight hypoxia encounters and the symptoms they experienced. These data were then compared to symptom data from a previous ROBD training survey using Chi-square analyses. Of the 566 aviators who completed the survey, 112 (20%) reported experiencing hypoxia symptoms in a tactical jet aircraft and 64 aviators (57%) indicated they were not wearing the required oxygen mask when the incident first occurred. The results also revealed only 21% of hypoxia events were reported in aviation hazard reports and the three most commonly recorded in-flight hypoxia symptoms were tingling (54%), difficulty concentrating (32%), and dizziness (30%). Chi-square analyses revealed statistically significant differences in frequency of reporting between 5 of 16 symptoms encountered in flight compared to ROBD training. The present investigation is the first survey-based study of hypoxia events in U.S. naval aviation. The study reveals in-flight, mask-on hypoxia has a similar overall reported symptom profile to ROBD training. Further, results suggest increased oxygen-mask compliance among these aviators may be necessary to effectively combat in-flight hypoxia.