captains. Since most operations were carried out separately by individual flights, this lack of rank structure in squadrons tended not to produce problems. During World War II, British AOP units used light, fixed-wing aircraft, almost exclusively several marks of Auster aircraft. The low speed, high manoeuvrability, small size (so aiding concealment at front-line landing grounds) and light weight of the Auster made this a much more suitable aircraft than the Lysander. The standard tactic of dealing with enemy fighter aircraft was to fly very low, normally around 30 feet above ground, around a hill or a wood. Although this also protected them from enemy ground fire, it resulted in many crashes into trees, poles, hills, cables and buildings. Casualty rates for AOP pilots turned out to be relatively low, compared to RAF pilots or infantrymen. One source of losses in combat was the aircraft being hit whilst flying through the path of outgoing shells. This was a particular hazard in intense bombardments: four aircraft were lost in this way during the crossing of the Rhine in March 1945. Postwar An AOP flight operated during the Malayan Emergency, but was redeployed to Korea during the Korean War at the request of the 1st Commonwealth Division. Another flight was sent by sea from the United Kingdom with its Auster AOP.6 aircraft packed in crates. A single Cessna L-19 was loaned by the US Army and found to be superior by the British pilots. Although all of the aircrew were Royal Artillery officers, these two flights were the only RAF units to operate from mainland Korea during the conflict. In 1957, the newly formed Army Air Corps was created from existing army units. Fixed-wing aircraft were steadily replaced by helicopters. The final AOP aircraft in British service was the Auster AOP.9, the last serving example of which was retired in March 1967. See also Forward air control Liaison aircraft No. 651 Squadron RAF References Bibliography Parham, Major General H.J. & Belfield, E.M.G. 1956, 1986. Unarmed Into Battle: The Story of the Air Observation Post. Warren & Son, for the Air O.P. Officers' Association, 2nd edition External links Army Air Corps History at www.army.mod.uk Canadian Warplane Heritage: Auster Beagle AOP at www.warplane.com Royal Air Force Military terminology