The mile high club (or MHC) is a slang term collectively applie to individuals who have engaged in sexual activity while on board an aircraft in flight at least 1 mile (5,280 ft/1,609 m AGL) above the Earth. There is no known formally constituted club so named. However, since "membership" of the "club" is really a matter of an individual asserting they have qualified, the qualifications for membership are open to some interpretation.