851 Squadron was a Royal Australian Navy Fleet Air Arm squadron. The squadron operated across two periods between 1954 and 1984, mainly in the training and transport roles.
851 Squadron was formed at HMAS Albatross as a land-based training and fleet support squadron on 3 August 1954. Its first commanding officer was Lieutenant D. Johns and it was initially equipped with Fairey Fireflies and C-47 Dakotas.
It was tasked primarily with training pilots and observers on the Firefly, and in this role the squadron's Dakotas were used as an observer training platform; they were also used to provide a transport and communications capability.
Throughout March 1956 the squadron was embarked upon HMAS Sydney, however, this was the squadron's only stint at sea as it was confined mainly to its training role.
The squadron was disbanded on 13 January 1958 following the reduction of the Navy's aircraft carrier fleet, which reduced the Navy's training requirements.
It remained off the order of battle until it was re-formed, again at Nowra, as a training and transport unit on 2 September 1968, equipped Dakotas and Grumman Trackers. It also operated in the VIP and fleet requirements roles, with the latter role sometimes seeing the squadron undertake search and rescue tasks, as well as patrolling the Bass Strait to maintain security around the economically important oil facilities there. A detachment was also sent to operate out of Darwin and Broome, to undertake fishery protection patrols. The Dakotas were replaced by Hawker-Siddeley 748s in 1973.
The squadron amalgamated with 816 Squadron RAN in July 1982 before being disbanded for a second, and final, time on 31 August 1984.
During its life the squadron operated the Fairey Firefly between August 1954 and January 1958; the C-47 Dakota between August 1954 and January 1958, and again between September 1968 and 1973; Grumman Trackers between September 1968 and August 1984; and Hawker-Siddeley 748.s between 1973 and August 1984).