A squadron in air force, army aviation, or naval aviation is mainly a unit comprising a number of military aircraft and their aircrews, usually of the same type, typically with 12 to 24 aircraft, sometimes divided into three or four flights, depending on aircraft type and air force. Land based squadrons equipped with heavier type aircraft such as long-range bombers, or cargo aircraft, or air refueling tankers have around 12 aircraft as a typical authorization, while most fighter equipped units have an authorized number of 18 to 24.