It's been known to happen clandestinely in aeroplane lavatories but now there are small airlines that make sex-while-flying their unique selling point.
Flamingo Air, based in Cincinnati, Ohio, encourages passengers to have sex midair. It is the world's only full-time flight service specially designed for people who want to join the 'mile-high club' - an informal term for people who claim to have had sex on a plane.
The small airline has five aircraft, one of which is reserved for its X-rated 'Flights of Fancy' wich cost $US475 (Rs 32000) per hour.
Airline chief David McDonald told news.com.cu, "Our passengers never land in a fully upright position."
For privacy there are no flight attendants and the pilot wears headphone. There are privacy curtains, a cushioned bed-the middle row of seat is removed- and a plush blanket, Champagne and chocolates are provided.
Flamingo air gets about three romantic flights per week. Love Cloud, its rival based in Las Vegas, has attracted customers from as afar as China, Europe and even Australia.