The mile high club is slang for the group of people who have had sexual intercourse on board an aircraft in flight. An alleged explanation for wanting to perform the act is the supposed vibration of the plane. Some theorize that people who engage in the act have fantasies about pilots or flight attendants, or a fetish about planes themselves, a type of mechanophilia. For others, the appeal of joining the mile-high club is the thrill of doing something taboo and the thrill of the risk of being discovered. History 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 [has sex with] a woman in a balloon one thousand yards from the Earth." (There is no further indication whether the bet was paid, or how any claim would be validated) During the First World War, German ace Oswald Boelcke was disciplined by superiors for taking a nurse up in the cockpit of his fighter, allegedly becoming the first person to qualify as a member of the club (although the claim is dubious, considering the cramped cockpit space and the pilot requirement to constantly keep hands and feet on the control stick and rudder pedals; others maintain it was a simple joyride). Pilot/engineer Lawrence Sperry and socialite Dorothy Rice Sims have been described as the first persons to engage in sex while flying in an airplane; the two flew in an autopilot-equipped Curtiss Flying Boat near New York in November 1916. The American National Transportation Safety Board reported on a 1991 incident in which sexual activity was at least partly responsible for the fatal crash of a Piper PA-34. In November 2007, the BBC reported a story headlined "Airline Bans A380 Mile-High Club". The Airbus A380 allows double beds to be installed in the first-class cabin, but Singapore Airlines' cabins are not soundproof; shortly after installing the new seats/beds, the airline requested that first-class travelers respect other passengers. Prevalence In one survey in the 2010s, 9% of Americans claimed to have had a sexual encounter in an airplane seat, 17% in the airplane bathroom, 5% with a stranger on an airplane, and 3% with a crew member. Reported instances Some