What is an air force?

The air force is the branch tasked with controlling airspace, striking from the air, and supporting the other branches with transport and surveillance. In most countries it began as part of the army and became independent during the 20th century: Britain's RAF in 1918, Spain's Ejército del Aire in 1939, the USAF in 1947. Many have since added "space" to their name and their missions, such as Spain's Ejército del Aire y del Espacio or France's Armée de l'Air et de l'Espace.

The usual structure is a pyramid. A chief of staff leads several functional commands: the operational command, which plans and executes missions; the personnel command; and the logistics support command, which maintains and procures equipment. Below them are wings, based at air bases, and within each wing the squadrons, grouping between 12 and 24 aircraft of the same type along with their pilots and mechanics. That chain also includes air surveillance squadrons operating radars, air defense units with missiles, air traffic control, meteorology, search and rescue, and training schools.

Pilots are a minority, around 5-10% of personnel. The rest are mechanics, weapons specialists, controllers, systems operators, medical staff, cyber defense specialists and administrative personnel. The USAF has about 320,000 active-duty personnel and more than 5,000 aircraft; Spain's Ejército del Aire y del Espacio, with around 20,000 personnel, operates Eurofighter and F-18 fighters, A400M and C-295 transports, A330 MRTT tankers, patrol aircraft, helicopters and trainers. Fleets are renewed every two or three decades, and each aircraft typically flies between 150 and 300 hours a year, most of it for training.