Flight (unit)

A flight is a military unit in an air force, naval air service, or army air corps. It is usually composed of three to six aircraft, with their aircrews and ground staff; or, in the case of a non-flying ground flight, no aircraft and a roughly equivalent number of support personnel. In most usages, multiple flights make up a squadron. The "flight" is also a basic unit for intercontinental ballistic missiles. Foreign languages equivalents include escadrille (French), escuadrilla (Spanish), esquadrilha (Portuguese) and Schwarm (German).

The use of the term "flight" to describe a collection of aircraft (typically four in the early days of aviation) dates back to around 1912. It has been suggested that the term was coined by technical sub-committee of the Committee of Imperial Defence which was examining the British air arrangements around the same time.

In the United Kingdom Royal Air Force and the other air forces of the Commonwealth, from where much air force terminology emanated, an aircraft flight, in the first decades of air forces, was commanded by a flight lieutenant, a rank equivalent to captain in armies and other air forces, or a naval lieutenant. More recently, however, it has become common for a flight to be led by a squadron leader—a formal rank distinct from a squadron commander—equivalent to an army major or naval lieutenant commander.

...
Wikipedia