Between 2010 and 2014, there were on average 23 cases of pilot incapacitation involving VH-registered airplanes worldwide, according to a study by the Australian Transportation Safety Board. Nearly three-quarters of the events happened in major airline operations—about one in every 34,000 flights—and the main cause was gastrointestinal illness; laser strikes were the next most common. The events usually had minimal effect on these multi-crew flights.
The study reports that smaller airline and general aviation operations had fewer events, but a wider variety of causes was behind the incapacitations, ranging from hypoxia to medical conditions. Seventy percent of pilot-incapacitation events in general aviation resulted in an accident or incident.
Since professional golfer Payne Stewart and five others died in the crash of a Learjet 35 on Oct. 25, 1999, NTSB records show 21 people died in 11 U.S. turbine business airplane accidents that were assumed to involve pilot incapacitation. Eleven people perished in the crashes of three business jets and 10 people were killed in eight turboprop accidents. According to the U.S. NTSB, medical conditions, fatigue, hypoxia and oxygen system failures were the probable causes of pilot incapacitation in these GA aircraft accidents.