Auster A.O.P.9 (Air Observation Post 9)
British 3-seat military observation aircraft

Archive Photos [1]

[Auster B-5 Auster AOP.9, XP281 Army, 1994 Imperial War Museum Duxford, Cambridgeshire, England [Ref. 1]]

Overview [2]

  • Role: military observation aircraft
  • Manufacturer: Auster Aircraft Limited
  • First flight: 19 March 1954
  • Introduced: 1955
  • Primary users: Army Air Corps, Royal Air Force, Indian Air Force
  • Number built: 182

The Auster AOP.9 was a British military air observation aircraft ("Air Observation Post") produced by Auster Aircraft Limited to replace the Auster AOP.6.

Design and Development [2]

The Auster AOP.9 was designed as a successor to the Auster AOP.6. Like its predecessor, it was a braced high-wing single engined monoplane with a fixed tailwheel undercarriage. Although having the same general appearance the AOP.9 was a new design with larger area wing and a more powerful engine. The wing and tail were metal skinned but the fuselage and ailerons fabric covered. The fin and rudder assembly were more angular in the new aircraft with a noticeable dorsal fillet. A combination of the more powerful 180 hp (134 kW) Blackburn Cirrus Bombardier engine, larger wings and large flaps gave it an improved take-off and landing performance compared with the AOP.6. It could operate from ploughed fields and muddy surfaces using low pressure tires and strengthened undercarriage.

The cabin held three seats, pilot and passenger side by side and the observer behind, facing either forwards or rearwards. The aircraft was also designed to be convertible into a two seat light transport with an interchangeable rear floor. In this configuration the observer sat alongside the pilot. The prototype (WZ662) first flew 19 March 1954. Auster Aircraft allotted their model designation B5 to the AOP.9 design.

Operational History [2]

Deliveries started to the Royal Air Force in February 1955, replacing AOP.6s in the regular AOP squadrons, the auxiliary squadrons disbanding in March 1957 before receiving AOP.9s. Until the formation of the Army Air Corps (AAC) in September 1957, Army personnel flew RAF aircraft based in RAF squadrons.

The aircraft were in action with No. 656 Squadron from September 1955, flying an average of 1,200 sorties per month. By the end of Operation Firedog in the Malaya on 31 July 1960, 656 Squadron's AOP.6 and AOP.9s had carried out 143,000 sorties. The AOP.9s were involved in several of Britain's other end of Empire conflicts; 653 Squadron AAC used them in Aden in the early 1960s, flying from Falaise, Little Aden. They stayed in service until 1966 and were the last fixed wing AOP aircraft used by the AAC, though their light transport role was taken over by Beavers.

In the 1970s 19 AOP.9s joined the UK civil register and in 2008 fourteen remain though only about three of these have a current certificate of airworthiness. The sole Beagle E3/Auster AOP.11 (G-ASCC) was flying until an accident in 2007.

Variants [2]

  • Auster AOP.9 Only production version, 182 built.
  • Auster AOP.11 Three-seat AOP machine with a 260 hp Continental IO-470-D 6-cylinder horizontally opposed more powerful engine, which raised the maximum speed to 142 mph (228 kmh) and the empty weight to 1,806 lb (816 kg). Apart from the engine, the AOP.11 was almost identical to its predecessor. Early in its career the undercarriage had spats, though these were later removed. Only one, a converted AOP.9 was produced, making its first flight on 18 August 1961 with serial XP254. A year later it was registered to Beagle aircraft, who had taken over Auster in 1960, as G-ASCC where it was known as the Beagle Mk 11, the E.3 or as the A.115. It was sold into private hands in 1971.
  • Auster 9M A number of army surplus aircraft were bought by Captain Mike Somerton-Rayner in 1967. One was converted as an Auster 9M with a 180 hp (134 kW) Avco Lycoming O-360-A1D piston engines. The 9M first flew on the 4 January 1968 and gained a Certificate of Airworthiness on 30 April 1968. The aircraft was still airworthy in 2009.

Operators [2]

Military Operators

  • Hong Kong: Royal Hong Kong Auxiliary Air Force about 4 ex-British AAC aircraft
  • India: About 35 aircraft, Indian Air Force, Indian Army
  • South Africa: South African Air Force about 2 aircraft
  • United Kingdom: about 145 aircraft

Specifications (AOP.9) [2]

General Characteristics

  • Crew: 2/3
  • Length: 23 ft 8½ in (7.24 m)
  • Wingspan: 36 ft 5 in (11.10 m)
  • Height: 8 ft 11 in (2.72 m)
  • Wing area: 197.6 ft² (18.36 m²)
  • Empty weight: 1,460 lb (663 kg)
  • Loaded weight: 2,100 (953)
  • Max takeoff weight: 2,330 lb (1,057 kg)
  • Powerplant: 1 × Blackburn Cirrus Bombardier 203 4-cylinder inverted inline piston, 173 hp (129 kw)


  • Maximum speed: 127 mph (204 km/h)
  • Cruise speed: 110 mph (178 km/h)
  • Range: 242 miles (389 km)
  • Service ceiling: 18,500 ft (5640 m)
  • Rate of climb: 920 ft/min (280 m/min)
  • Wing loading: 10.4 lb/ft² (50.4 kg/m²2)
  • Power/mass: 11.9 lb/hp (7.25 kg/kW)


  1. Shupek, John. Auster AOP.9 Air Observation Post images via The Skytamer Archive, Copyright © 2009 Skytamer Images. All Rights Reserved
  2. Wikipedia, the free encyclopedia. Auster AOP.9

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