Hypoxia-Like Events in UK Typhoon Aircraft from 2008 to 2017

Area of Science:

• Aviation Safety
• Aerospace Medicine
• Physiology

Background:

• Concerns exist regarding aircraft life support system (LSS) effectiveness in preventing in-flight hypoxia.
• An investigation into hypoxia-like events in a UK front-line combat aircraft was initiated.

Purpose of the Study:

• To analyze reported hypoxia-like incidents in UK combat aircraft.
• To assess the effectiveness of the aircraft's life support system (LSS) and determine the probable causes of reported symptoms.

Main Methods:

• A decade of UK Defense Air Safety Occurrence Reports (DASORs) for the Typhoon aircraft were reviewed.
• Qualitative analysis examined event narratives, LSS function, and symptom causality, assessing the likelihood of hypobaric hypoxia.

Main Results:

• 18 reports of suspected hypoxia were identified; only 2 cases were probable (oxygen bottle failure, mask-off depressurization).
• Hyperventilation was the likely cause in 13 cases (65%); 2 cases were attributed to minor illness.
• The Typhoon LSS effectively provided altitude protection, even during cabin depressurization events.

Conclusions:

• Probable hypoxia is rare in Typhoon aircraft, with only 2 confirmed cases in over 150,000 flying hours.
• The aircraft's life support system (LSS) is effective.
• Most reported symptoms are idiosyncratic and likely caused by hyperventilation, not LSS malfunction.