Question: what did Volunteer Groundcrew of the Army Air Corps use in isolated areas.

full_context: Document 1: Sikorsky R-4: The Sikorsky R-4 was a two-seat helicopter designed by Igor Sikorsky with a single, three-bladed main rotor and powered by a radial engine. The R-4 was the world's first large-scale mass-produced helicopter and the first helicopter used by the United States Army Air Forces, the United States Navy, the United States Coast Guard and the United Kingdom's Royal Air Force and Royal Navy. In U.S. Navy and U.S. Coast Guard service, the helicopter was known as the Sikorsky HNS-1. In British service, it was known as the Hoverfly.
Document 2: Tiltrotor: A tiltrotor is an aircraft which generates lift and propulsion by way of one or more powered rotors (sometimes called "proprotors") mounted on rotating engine pods or nacelles usually at the ends of a fixed wing or an engine mounted in the fuselage with drive shafts transferring power to rotor assemblies mounted on the wingtips. It combines the vertical lift capability of a helicopter with the speed and range of a conventional fixed-wing aircraft. For vertical flight, the rotors are angled so the plane of rotation is horizontal, lifting the way a helicopter rotor does. As the aircraft gains speed, the rotors are progressively tilted forward, with the plane of rotation eventually becoming vertical. In this mode the wing provides the lift, and the rotor provides thrust as a propeller. Since the rotors can be configured to be more efficient for propulsion (e.g. with root-tip twist) and it avoids a helicopter's issues of retreating blade stall, the tiltrotor can achieve higher speeds than helicopters.
Document 3: 129th Rescue Squadron: The 129th Rescue Squadron (129 RQS) is a unit of the California Air National Guard 129th Rescue Wing located at Moffett Federal Airfield, Mountain View, California. The 129th is equipped with the HH-60G Pave Hawk helicopter.
Document 4: 9 Regiment Army Air Corps: 9 Regiment Army Air Corps was a regiment of the Army Air Corps (AAC). It merged with 1 Regiment Army Air Corps in 2016 and is based at RNAS Yeovilton (HMS Heron).
Document 5: No. 675 (The Rifles) Squadron AAC: No. 675 (The Rifles) Squadron Army Air Corps (675 Sqn) is a British Army Army Reserve groundcrew aviation support squadron. It is part of 6 Regiment Army Air Corps (6 Regt AAC). It is located in the city of Taunton, with a detachment currently at RNAS Yeovilton, in the county of Somerset.
Document 6: No. 110 Helicopter Unit, IAF: No. 110 Helicopter Unit (Vanguards) is a Helicopter Unit and is equipped with Mil Mi-8 and based at Kumbhirgram Air Force Station.
Document 7: Vought-Sikorsky VS-300: The Vought-Sikorsky VS-300 (or S-46) was a single-engine helicopter designed by Igor Sikorsky. It had a single three-blade rotor originally powered by a 75 horsepower (56 kW) engine. The first "free" flight of the VS-300 was on 13 May 1940. The VS-300 was the first successful single lifting rotor helicopter in the United States and the first successful helicopter to use a single vertical-plane tail rotor configuration for antitorque. With floats attached, it became the first practical amphibious helicopter.
Document 8: 6 Regiment Army Air Corps: 6 Regiment Army Air Corps is the sole Army Reserve regiment of the Army Air Corps (AAC). The regiment operates in a groundcrew role, providing support to Army Aviation units of the Joint Helicopter Command.
Document 9: Helicopter: A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward, and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of VTOL (vertical takeoff and landing) aircraft cannot perform.
Document 10: Bell UH-1 Iroquois: The Bell UH-1 Iroquois (nicknamed "Huey") is a utility military helicopter powered by a single turboshaft engine, with two-blade main and tail rotors. The first member of the prolific Huey family, it was developed by Bell Helicopter to meet a United States Army's 1952 requirement for a medical evacuation and utility helicopter, and first flew in 1956. The UH-1 was the first turbine-powered helicopter to enter production in 1960 for the United States military, and more than 16,000 have been built since.
Document 11: No. 679 (The Duke of Connaught's) Squadron AAC: No. 679 (The Duke of Connaught's) Squadron AAC is a Helicopter Support squadron made up of the Volunteer Groundcrew of the Army Air Corps.
Document 12: No. 656 Squadron RAF: No. 656 Squadron RAF was an Air Oberservation Post unit of the Royal Air Force in India and Burma during the Second World War and afterwards in British Malaya. Numbers 651 to 663 Squadron of the RAF were Air Observation Post units working closely with British Army units in artillery spotting and liaison. A further three of these squadrons, 664–666, were manned with Canadian personnel. Their duties and squadron numbers were transferred to the Army with the formation of the Army Air Corps on 1 September 1957 With this it became 656 Light Aircraft Squadron Army Air Corps.
Document 13: Harbin Z-20: The Harbin Z-20 or Zhi-20 is a medium lift helicopter produced in the Northeast of China. Its first flight was on 23 December 2013. The helicopter has a maximum takeoff weight in the range of 10 tons, can drop troops at locations of up to 3,000 ft altitude, and could operate from the Chinese aircraft carrier Liaoning. It is thought to be comparable to the US made Sikorsky UH-60 Black Hawk helicopter, the civilian Sikorsky S-70C-2 variant of which has been used by the People's Liberation Army since 1984. Some sources suggest that the Z-20 is a copy of the Black Hawk and link the design to the Black Hawk that was abandoned by US special forces in Pakistan during the operation to kill Osama bin Laden on 1 May 2011. The sources say that Pakistan allowed Chinese officials to examine the Black Hawk wreckage. However, Aviation Week also points out that although some aspects of the design do appear similar, such as the tail wheel arrangement, there are also marked differences. For example, the Chinese Z-20 has a five blade rotor compared with the Black Hawks' four blades.
Document 14: 2 Regiment Army Air Corps: 2 (Training) Regiment Army Air Corps is a regiment of the British Army's Army Air Corps. It is responsible for all of the Army Air Corps' groundcrew Phase 2 and 3 training, as well as the Ground Support Commanders Course for officers. The Regiment is based at Middle Wallop and is made up of two squadrons:
Document 15: List of surviving Sikorsky CH-54s: The Sikorsky CH-54 Tarhe is a twin-engine heavy-lift helicopter designed by Sikorsky Aircraft for the United States Army. The civil version is the Sikorsky S-64 Skycrane. The Army purchased 105 CH-54s before its discontinuation. The S-64 Aircrane is still in production. There are currently numerous complete and partial airframes in existence for this aircraft. Some CH-54's and some S-64's (both E and F models) are owned, and have been remanufactured, by Erickson Air-Crane Inc."
ground_truth: is a type of rotorcraft