Payload is the carrying capacity of an
aircraft or
launch vehicle, usually measured in terms of weight. Depending on the nature of the flight or mission, the payload of a vehicle may include
cargo,
passengers,
flight crew,
munitions, scientific instruments or experiments, or other equipment. Extra fuel, when optionally carried, is also considered part of the payload. In a commercial context (i.e., an
airline or
air freight carrier), payload may refer only to revenue-generating cargo or paying passengers.