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.
In most armed forces, two or more squadrons will form a group or a wing. Some air forces (including the Royal Air Force, Royal Netherlands Air Force, Belgian Air Component, German Air Force, Republic of Singapore Air Force, and United States Air Force) also use the term squadrons for non-flying ground units (e.g., radar squadrons, missile squadrons, aircraft maintenance squadrons, security forces squadrons, civil engineering squadrons, operations management squadron, medical squadrons, etc.).
United States military air services
In contrast to United States Air Force units where flying squadrons are separate from supporting administrative and aircraft maintenance squadrons, flying squadrons in U.S. Naval Aviation (United States Navy and United States Marine Corps) typically contain both embedded administrative support functions and organizational level aircraft maintenance functions, plus all their associated personnel as part of the total squadron manning.
In United States Marine Corps Aviation the nomenclature "squadron" is also used to designate all battalion-equivalent, aviation support organizations. These squadrons include: wing headquarters, tactical air command, air control, air support, aviation logistics, wing support, and wing communications squadrons.
Also in contrast to USAF flying squadrons, most tactical sea-based and land-based U.S. Naval Aviation squadrons (USN and USMC), vice training squadrons and test and evaluation squadrons, usually do not have more than 12 aircraft authorized/assigned at any one time. Exceptions are USN helicopter mine countrmeasures squadrons (17 MH-53), USMC composite medium tilt-rotor squadrons (12 MV-22s, 6 AH-1s, 4 CH-53s, 3 UH-1s, and 6 AV-8s), heavy helicopter (16 CH-53s) and light/attack helicopter (18 AH-1s and 9 UH-1s) squadrons, and Marine attack squadrons (16 AV-8s).
Although part of U.S. naval aviation, United States Coast Guard aviation units are centered on an air station versus a squadron or group/wing organizational structure. The one exception to this is the Coast Guard's Helicopter Interdiction Squadron (HITRON), which is engaged primarily in counter-narcotics (CN) interdiction operations.
In U.S. Army Aviation, flying units may be organized in battalions or squadrons (air cavalry only) reporting to an aviation brigade.
An escadron is the equivalent unit in France's Armée de l'Air. It is normally subdivided into escadrilles of eight aircraft.
In the Air Training Corps of the United Kingdom and many Commonwealth nations, a Squadron is a group of cadets who parade regularly.
In the U.S. Civil Air Patrol, a squadron is the basic administrative unit.
In the Swedish Air Force a helicopter squadron (helikopterskvadron) is a detachment from the "Helicopter Wing" (Helikopterflottiljen).