U.S. regulations require pilots to don and use their oxygen masks when they venture above Flight Level (FL) 350 (approximately 35,000 ft).1 If an aircraft should suddenly depressurize while flying at that altitude, the pilot’s time of useful consciousness, also called effective performance time, is 30 to 60 seconds, according to the U.S. Federal Aviation Administration (FAA). Effective performance time decreases as altitude increases. For example, it’s 15 to 20 seconds at FL 400 and 9 to 12 seconds at FL 450.2
The FAA stresses that these are average times and that effective performance time is affected by factors such as a pilot’s health and physical condition. Moreover, impairment of a pilot’s ability to make decisions and take action begins almost immediately following a rapid depressurization.
However, using supplemental oxygen as a proactive measure at high altitude often is neglected because of the unpleasant experience of wear…
