support, and wing communications squadrons. In contrast to their USN counterparts, USMC flying squadrons and aviation support squadrons, while having a commanding officer (CO) at the lieutenant colonel level, may not have an equivalent rank executive officer (XO), but are moving more toward the USN model. USMC aviation (Flying) squadron XO's are aeronautically designated officers in the rank of Lt.Col or Major. 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 countermeasures squadrons (17 MH-53), USMC "composite" medium tilt-rotor squadrons assigned afloat as the Aviation Combat Element (ACE) of a Marine Expeditionary Unit (MEU), (12 MV-22s, 6 AH-1s, 4 CH-53s, 3 UH-1s, and 6 AV-8s). Other squadrons with a large number of Primary Aircraft Assigned (PAA) include Marine heavy helicopter squadrons (16 CH-53s), Marine light/attack helicopter squadrons (18 AH-1s and 9 UH-1s), 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 or air facility 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 the United States Army Aviation Branch, flying units may be organized in battalions or squadrons (the latter for air cavalry only) reporting to an aviation brigade. Aircraft maintenance activities are typically assigned to an aviation maintenance company or element in the battalion or brigade. In the U.S. Civil Air Patrol (CAP), a squadron is the basic administrative unit. As the official civilian auxiliary of the U.S. Air Force, CAP follows the USAF organizational model. Other countries An escadron is the equivalent unit in France's French Air and Space Force (Armée de l'air et de l'espace). It is normally subdivided into escadrilles of eight aircraft. The Spanish Air and Space Force and some air forces of other Spanish-speaking countries follow that tradition (with a squadron called an escuadron and a flight called an escuadrilla), as does the Brazilian Air Force with esquadrão and esquadrilha respectively. The Royal Canadian Air Force and the Belgian Air Component on the other hand use escadrille as the equivalent of a squadron. The Italian Air Force uses gruppo (group) to denominate