The term mile-high club (or MHC) is a slang term applied collectively to individuals who have had sexual intercourse while on board a flying aircraft. The exact requirements for membership are open to some interpretation.
One explanation for the act is the vibration of the plane, which may speed or improve arousal. Some say they have fantasies about pilots or flight attendants, or a fetish about planes themselves. For others, the appeal of joining the MHC is the thrill of doing something taboo and the thrill of the risk of being discovered.
An early reference to the concept is found in the betting book for Brooks's, a London gentlemen's club. The 1785 entry (only two years after the first successful balloon ascent by Étienne Montgolfier) reads: "Ld. Cholmondeley has given two guineas to Ld. Derby, to receive 500 Gs whenever his lordship ***** a woman in a balloon one thousand yards from the Earth." (However, there is no further indication that the bet was paid, or even how they would check it if it was claimed.)
A website using the name Mile High Club regards the "Club's" "founder" as pilot and design engineer Lawrence Sperry, along with "socialite Mrs. Waldo Peirce"(Dorothy Rice Sims) citing their flight in an autopilot-equipped Curtiss Flying Boat near New York in November 1916. The American transportation authority NTSB reports one case in which sexual activity is at least partly responsible for an aviation accident.
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