United States Marine Corps Aviation is the air component of the United States Marine Corps. Marine aviation has a very different mission and operation than its ground counterpart, and thus, has many of its own histories, traditions, terms, and procedures.
All Marine aviation falls under the influence of the Deputy Commandant for Aviation, whose job is to advise the Commandant of the Marine Corps in all matters relating to aviation, especially acquisition of new assets, conversions of current aircraft, maintenance, operation, and command.
The organic aviation capability of the Marine Corps is essential to its mission. The Corps operates both rotary-wing and fixed-wing aircraft mainly to provide transport and close air support to its ground forces. However, other aircraft types are also used in a variety of support and special-purpose roles.
Today, Marine aviation is task organized to support the Marine Air-Ground Task Force, as the aviation combat element, by providing six functions: assault support, anti-aircraft warfare, offensive air support, electronic warfare, control of aircraft and missiles, and aerial reconnaissance.
Marine aviation officially began on May 22, 1912, when First Lieutenant Alfred A. Cunningham reported to Naval Aviation Camp in Annapolis, Maryland, "for duty in connection with aviation." As the number of Marine Aviators grew, so did the desire to separate from Naval Aviation, a dream realized on January 6, 1914, when First Lieutenant Bernard L. Smith was directed to Culebra, Puerto Rico, to establish the Marine Section of the Navy Flying School.
In 1915, the Commandant of the Marine Corps authorized the creation of a Marine Corps aviation company consisting of 10 officers and 40 enlisted men. The first official Marine flying unit arrived with the February 17, 1917, commissioning of the Marine Aviation Company for duty with the Advanced Base Force at the Philadelphia Navy Yard.
The first major expansion of the Marine Corps' air component came with America's entrance into World War I in 1917. Wartime expansion saw the Aviation Company split into the First Aeronautic Company which deployed to the Azores to hunt U-Boats in January 1918 and the First Marine Air Squadron which deployed to France as the newly renamed 1st Marine Aviation Force in July 1918 and provided bomber and fighter support to the Navy's Day Wing, Northern Bombing Group. By the end of the war, several Marine Aviators had recorded air-to-air kills, collectively they had dropped over fourteen tons of bombs. and their number totals included 282 officers and 2,180 enlisted men operating from 8 squadrons.In 1919 the 1st Division/Squadron 1 was formed from these units, and exists as VMA-231.
The end of World War I saw Congress authorize 1,020 men for Marine aviation and the establishment of permanent air stations at Quantico, Parris Island and San Diego. The United States also embraced its role of global power and the Marine Corps became the preferred force for military intervention and where the Marines went so went Marine aviation. During the Banana Wars, while fighting bandits and insurgents in places like Haiti, the Dominican Republic and Nicaragua, Marine Aviators began to experiment with air-ground tactics and making the support of their fellow Marines on the ground their primary mission. It was in Haiti that Marines began to develop the tactic of dive bombing and in Nicaragua where they began to perfect it. While other nations and services had tried variations of this technique, Marine Aviators were the first to embrace it and make it part of their tactical doctrine. Even prior to the events in the Caribbean pioneering Marine aviators such as Alfred Cunningham had noted in 1920 that, "...the only excuse for aviation in any service is its usefulness in assisting the troops on the ground to successfully carry out their missions."
It was not until May 3, 1925 that the Marine Corps officially appeared in the Navy's Aeronautical Organization when Rear Admiral William A. Moffett, then Chief of the Navy's Bureau of Aeronautics, issued a directive officially authorizing three fighting squadrons. Also taking place during the 1920s was that Marine squadrons began qualifying on board aircraft carriers. However, in terms of mission and training, the assignment of two Marine scouting squadrons as component units of the Pacific Fleet carriers would be one of the greatest advancements for Marine aviation. Prior to this Marine squadrons were loosely controlled with regard to doctrine and training. This assignment enabled nearly 60% of active duty aviators at the time to be exposed to a disciplined training syllabus under a clearly defined mission.
The turning point for the long-term survival of Marine Air came with the structural change of the establishment of the Fleet Marine Force in 1933. This shifted Marine doctrine to focus less on expeditionary duty and more on supporting amphibious warfare by seizing advance naval bases in the event of war.  This also saw the establishment of Aircraft One and Aircraft Two to replace the old Aircraft Squadron, East Coast and Aircraft Squadron, West Coast that had supported operations in the Caribbean and China as part of their expeditionary duties. This organization would remain until June 1940 when Congress authorized the Marine Corps 1,167 aircraft as part of its 10,000 plane program for the Navy. Just prior, in 1939, the Navy's General Board published a new mission for Marine Aviation, which stated
Marine Aviation is to be equipped, organized and trained primarily for the support of the Fleet Marine Force in landing operations and in support of troop activities in the field; and secondarily as replacement for carrier based naval aircraft.
World War II would see the Marine Corps' air arm expand rapidly and extensively.They would reach their peak number of units with 5 air wings, 31 aircraft groups and 145 flying squadrons. During the war, and for the next fifty years, the Battle of Guadalcanal would become a defining point for Marine Aviation . The great takeaways were the debilitating effects of not having air superiority, the vulnerability of targets such as transport shipping and the vital importance of quickly acquiring expeditionary airfields during amphibious operations.. Because of the way the Pacific War unfolded, Marine Aviation was not able to achieve its 1939 mission of supporting the Fleet Marine Force at first. For the first two years of the war the air arm spent most of its time protecting the fleet and land based installations from attacks by enemy ships and aircraft. This began to change after the Battle of Tarawa as the air support for ground troops flown by Navy pilots left much to be desired. After the battle, General Holland Smith recommended, "Marine aviators, thoroughly schooled in the principles of direct air support," should do the job. The Battle of New Georgia saw the first real close air support provided to Marine ground forces by Marine Air, the Battle of Bougainville and the campaign to retake the Philippines saw the establishment of air liaison parties to coordinate air support with the Marines fighting on the ground and the Battle of Okinawa brought most of it together with the establishment of aviation command and control in the form of Landing Force Air Support Control Units During the course of the war Marine Aviators were credited with shooting down 2,355 Japanese aircraft while losing 573 of their own aircraft in combat, they had 120 aces and earned 11 Medals of Honor. Immediately following the war the strength of the Marine Corps flying arm was drastically cut as part of the post war drawdown of forces. Their active strength fell from 116,628 personnel and 103 squadrons on August 31, 1945 to 14,163 personnel and 21 squadrons on June 30, 1948. They also maintained another 30 squadrons in the Marine Air Reserve. Also during this time, the Secretary of Defense for then President Harry Truman, Louis A. Johnson, attempted to eliminate Marine Corps aviation by transferring its air assets to other services, and even proposed to progressively eliminate the Marine Corps altogether in a series of budget cutbacks and decommissioning of forces.
After World War II, propeller aircraft were gradually phased out as jet aircraft improved and helicopters were developed for use in amphibious operations. The first Marine jet squadron came in November 1947 when VMF-122 fielded the FH Phantom, and four years later VMF-311 would be the first Marine jet squadron to be used in combat providing close air support for the Marines and soldiers on the ground in December 1950 flying the F9F Panther. HMX-1, the first Marine helicopter squadron, stood up in November 1947. Marine helicopters — VMO-6 flying the HO3S1 helicopter — made their combat debut in August 1950's Battle of Pusan Perimeter. January 1951 saw the activation of HMR-161, the world's first helicopter transport squadron. In February 1957, VMA-214 became the first Marine squadron to be certified for "special weapons delivery": dropping nuclear weapons. A handful of squadrons received certification. though eventually all nuclear weapons were turned over to Navy and Air Force responsibility.
The Korean and Vietnam Wars saw the size of Marine Aviation rebound from its post-WWII lows, emerging as the force that exists today, consisting of four air wings, 20 aircraft groups and 78 flying squadrons. By the end of the Vietnam War, the Marine Air-Ground Task Force had grown dependent on its multi-mission inventory of fixed- and rotary-wing aircraft, which could operate from land or sea bases to support Marines on the ground.
Marine Aviators deployed to the Middle East for Operation Desert Shield and Operation Desert Storm, then to Operation Enduring Freedom in Afghanistan and Operation Iraqi Freedom. 2006 saw Marine Aviation at its highest operational level since the Vietnam War, flying more than 120,000 combat hours in to support operations in and near Afghanistan and Iraq. Despite their aging aircraft and high operating tempo, Marine Aviation maintained a 74.5-percent mission-capable rate, higher than the 62 percent of the USAF's F-22 Raptor. As of 2010, the aircraft fleet is undergoing another transformation.
Since the the Corps as a whole began to grow in 2007, Marine Aviation expanded with it, and continues to grow. Several new squadrons have been activated, with HMLA-567, VMFAT-501, and VMU-4 pending. Some support units will gain personnel and equipment. The Corps intends to buy 340 F-35Bs to replace all F/A-18 Hornets, AV-8B Harrier IIs and EA-6B Prowlers in the fighter, attack, and electronic warfare roles. The MV-22B Osprey is replacing the CH-46 Sea Knight and the remaining CH-53D Sea Stallion (most of which were replaced by CH-53E Super Stallions). The Corps has transitioned all East Coast CH-46 squadrons to the MV-22, which has made its first combat deployments and Marine Expeditionary Unit deployments. Remaining CH-53Es will eventually be replaced by the CH-53K model. The KC-130J Super Hercules will replace all other C-130 models. As part of the H-1 upgrade program, UH-1N Twin Hueys will be replaced or converted to UH-1Y Venoms, while AH-1W SuperCobras will upgrade to AH-1Z Vipers. The VH-3D Sea Kings and the VH-60N Blackhawks of HMX-1 were to be replaced by the VH-71 Kestrel, but the future of the program is in doubt with budget cuts by Secretary of Defense Robert Gates. Unmanned aerial vehicle programs will be upgraded in tiers, with the RQ-7 Shadow currently replacing the RQ-2 Pioneer and the RQ-11 Raven replacement planned. They have also been in the lead in looking at unmanned helicopters to resupply troops by unmanned helicopters at forward operating bases in places such as Afghanistan.
The basic tactical and administrative unit of United States Marine Corps aviation is the squadron, which is the size/organization equivalent of a battalion. Fixed-wing aircraft squadrons are denoted by the letter "V", which comes from the French verb "Voler" (to fly). Rotary wing (helicopter) squadrons use "H." Squadrons flying lighter than air vehicles (balloons), which were active from World War I to 1943, were indicated by the letter "Z" in naval squadron designation. Marine squadrons are always noted by the second letter "M." Squadron numbering is not linear as some were numbered in ascending order and others took numbers from the wing or the ship to which they were assigned. From 1920 to 1941, Marine flying squadrons were identified by one digit numbers. This changed on July 1, 1941 when all existing squadrons were redesignated to a three-digit system. The first two numbers were supposed to identify the squadron's parent group but with the rapid expansion during the war and frequent transfer of squadrons this system fell apart. Each squadron has a unique two digit tail code painted onto the vertical stabilizer that tends to remain the same for the entire life of the squadron (though it will sometimes change temporarily as a squadron is assigned to a ship).
The squadron is sometimes further divided into sections. Traditionally, the lead aircraft belongs to the commanding officer.
The largest level in Marine aviation is the Marine Aircraft Wing, the equivalent of a division. Wings are usually grouped with a Marine division and a Marine Logistics Group to form a Marine Expeditionary Force. Administratively, Marine aviation is organized into three active duty MAWs and one reserve MAW. MAWs are designed to provide units in support of MAGTF or other operations. Each MAW has a unique organizational structure. The MAW may be reinforced with assets from other MAWs to provide the necessary assets to meet mission requirements. It is organized into a MAW HQ, several Marine Aircraft Groups (MAGs), a Marine Air Control Group (MACG) and a Marine Wing Support Group (MWSG). Each MAW is served by a Marine Wing Headquarters Squadron (MWHS) (see: MWHS-1, MWHS-2, and MWHS-3). The mission of the MAW is to conduct air operations in support of the Marine Forces to include offensive air support, anti-aircraft warfare, assault support, aerial reconnaissance, electronic warfare, and the control of aircraft and missiles. As a collateral function, the MAW may participate as an integral component of naval aviation in the execution of such other Navy functions as the Fleet Commander may direct
All Marine Corps aviation falls under the cognizance of the Deputy Commandant for Aviation (DCA) at Headquarters Marine Corps, with the cooperation of the United States Navy. There, plans for all aspects of aviation are created and managed, including acquisition of new aircraft, training, maintenance, manpower, etc. HQMCA creates Transitional Task Forces to assist units in transitioning between aircraft and aircraft versions. The current head of Marine Corps Aviation is the Deputy Commandant for Aviation Lieutenant General George Trautman.
The Deputy Commandant of Aviation also commands Marine Corps Detachments at Naval Air Weapons Station China Lake and Naval Air Station Patuxent River. The NAS China Lake Marines are responsible to DCA for the test and evaluation of all weapons and weapon systems and for electronic warfare development. While those at NAS Pax River work with Naval Air Systems Command and are responsible for developing, acquiring and supporting naval aeronautical and related technology systems for the operating forces. 
Due to the range and space needed to operate aircraft, each MAW spreads its groups and squadrons amongst several Marine Corps Air Stations (MCAS), as well as offering detachments/liaisons (and occasionally full units) to airports, Air Force Bases and Naval Air Stations. Each MCAS maintains its own base functions as well as air traffic control and facilities (often with a Headquarters and Headquarters Squadron of its own).
All Marine pilots and flight officers are trained and qualified as Naval Aviators or Naval Flight Officers by the Navy. Prospective aviators receive their commissions and attend The Basic School just as all other Marine officers do, then report to Marine Aviation Training Support Group 21 to attend Aviation Preflight Indoctrination at Naval Air Station Pensacola, Florida. There they receive instruction in aerodynamics, aircraft engines and systems, meteorology, navigation, and flight rules and regulations. Following completion, they are assigned to Primary Flight Training at Marine Aviation Training Support Group 22, Naval Air Station Corpus Christi, Texas or remain in Pensacola, Florida. Upon successful completion of Primary Flight Training, they will select which type of aircraft they would like to fly, in accordance with the needs of the Corps.
After selection, student aviators are assigned to Advanced Flight Training in their particular field (jet, propeller, or rotary wing). Upon completion, students are designated as Naval Aviators and are awarded the Naval Aviator Insignia. From that point, they are trained at a Fleet Replacement Squadron for the specific aircraft they will be flying. A few uncommon aircraft are taught by the Navy or Air Force, or in the case of HMX-1, by the company that created the aircraft. After completion, aviators are assigned to their first squadron.
Flight Officers, after Aviation Preflight Indoctrination, continue their own training path by staying at Pensacola and training further in navigation and avionics. After Advanced NFO training, they receive their wings and are assigned to their first duty squadron.
Enlisted aircrew also serve on some aircraft (mostly helicopters). They are trained at NAS Pensacola and are eligible to wear the Aircrew insignia.
Marine aviators are eligible to earn medals such as the Distinguished Flying Cross for heroism in combat and the Air Medal for meritorious achievement in flight as well as the Gray Eagle Award for seniority. Pilots in combat have a chance to become flying aces.
The Marine light attack helicopter squadrons (HMLA) are composite squadrons of AH-1W SuperCobras and UH-1N Iroquois (also known as the Huey), as the airframes have over 80% commonality. Both are slated to be replaced by the AH-1Z Viper in 2011 and the UH-1Y Venom in 2009, respectively as part of the H-1 upgrade program. These provide light-attack and light transport capabilities. Marine medium helicopter (HMM) squadrons fly the CH-46E Sea Knight medium-lift transport helicopters; but are converting to the V-22 Osprey, a tilt-rotor aircraft with superior range and speed, and are being re-named as "Marine medium tilt-rotor" (VMM) squadrons. Marine heavy helicopter (HMH) squadrons fly the CH-53D Sea Stallion and CH-53E Super Stallion helicopter for heavy-lift missions. These will eventually be replaced with the upgraded CH-53K, currently under development.
Marine attack squadrons (VMA) fly the AV-8 Harrier II; while Marine Fighter-Attack (VMFA) and Marine (All Weather) Fighter-Attack (VMFA(AW)) squadrons, respectively fly both the single-seat (F/A-18C) and dual-seat (F/A-18D) versions of the F/A-18 Hornet strike-fighter aircraft. The AV-8B Harrier II is a VTOL aircraft that can operate from amphibious assault ships, land air bases and short, expeditionary airfields. The F/A-18 can only be flown from land or aircraft carriers. Both are slated to be replaced by the F-35B, the STOVL version of the F-35 Lightning II..
In addition, the Corps operates its own organic electronic warfare (EW) and aerial refueling assets in the form of the EA-6B Prowler and KC-130 Hercules. In Marine transport refuelling (VMGR) squadrons, the Hercules doubles as a ground refueller and tactical-airlift transport aircraft. With the addition of the ISR / Weapon Mission Kit, the KC-130J will be able to serve as an overwatch aircraft and can deliver ground support fire in the form of 30mm cannon fire, Hellfire missiles, and precision-guided bombs. This power, nicknamed the "Harvest Hawk", can be used in scenarios where precision is not a requisite, such as area denial. Serving in Marine Tactical Electronic Warfare (VMAQ) Squadrons, the Prowler is the main tactical electronic warfare aircraft left in the U.S. inventory, though Navy squadrons have begun replacing it with the EA-18G Growler. It has been labeled a "national asset" and is frequently borrowed to assist in any American combat action, not just Marine operations. Since the retirement of the EF-111A Raven in 1998, the Air Force's only EW aircraft, Marine Corps and Navy aircraft have provided electronic warfare support to Air Force units.
The Marines also operate two Marine unmanned aerial vehicle (UAV) squadrons (VMU), with the RQ-7 Shadow UAV for tactical reconnaissance. These squadrons also fly the Boeing ScanEagle and have recently retired the RQ-2 Pioneer..
Marine Fighter Training Squadron 401 (VMFT-401), operates F-5E, F-5F and F-5N Tiger II aircraft in support of air combat adversary (aggressor) training. Marine Helicopter Squadron One (HMX-1) operates the VH-3D Sea King medium-lift and VH-60N Nighthawk light-lift helicopters in the VIP transport role, previously planned to be replaced by the cancelled VH-71 Kestrel. Marine Transport Squadron One (VMR-1) utilizes several aircraft to transport VIPs and critical logistics, to include the C-9B Skytrain II, UC-35C/D Citation Ultra/Encore, C-12B/F Huron, and C-20G Gulfstream IV, as well as the HH-46E in a search and rescue role. A single Marine Corps C-130 Hercules, "Fat Albert," is used to support the U.S. Navy's flight demonstration team, the "Blue Angels".