Document Type


Publication Date





Flight time is an important index of the flight exposure of pilots and is used in estimating the accident rates of pilots, but we are not aware of prior attempts to determine how the underlying data are obtained. This study used two surveys of civilian U.S. pilots to learn how they measured and recorded flight time. Pilots used a timer, watch, the Hobbs meter or tachometer to measure the duration of flights. Professional pilots flying on scheduled flights used company or block time as the criterion of the duration of a flight, while 79% of private pilots used the time from engine(s)-on to shut-down and others the time from take-off to landing. About 80% of the pilots made a temporary or permanent record of the hours flown on the day of the flight. But, only about 71% of pilots with class III medical certificates, 58% with class II and 42% with class I reviewed their flight logs before the medical exam. The accuracy of the flight hours data could be improved if pilots used a uniform criterion of flight time, recorded it before leaving the cockpit and checked their flight logs before the medical exam.