RAAF Flying Boat Maintenance Base


Admiralty Island -Trinity Inlet, Cairns 4870

Japanese bombing of Port Moresby in February 1942 meant that a safer anchorage was required for RAAF No.11 and 20 Squadron Catalina flying boats operating from there. The port of Bowen served as a base for about six months until both squadrons moved north to establish their main maintenance and refuelling base at Cairns. In 1944 a permanent flying boat slipway of reinforced concrete was constructed on the seaward side of Admiralty Island facing the incoming tide. This enabled damaged aircraft coming in from the Coral Sea to run straight onto the slipway on landing.

Today most of these installations have rusted away or been consumed by mangroves, but surviving evidence includes several barges, an area of prefabricated steel wharf, and a concrete slipway.


Cairns-based Catalinas commenced their nightly operations known as the 'Milk Run' early in November 1942. These were nightly patrols to blockade Japanese shipping movements from the north into the Buna, Salamaua, Lae and Finschaffen districts. For nine months the Catalinas left base in time to reach the approaches to the patrol area about dusk, usually landing at Port Moresby or Milne Bay in the morning to refuel for the flight back to Cairns. In the first four months of operations from Cairns, No.11 and 20 Squadrons between them, flew a total of 20,152 hours and dropped a total of 480 tons of bombs.

Maintenance and refuelling facilities were developed on the mangrove shoreline of Admiralty Island, close to the main flying boat anchorages on Trinity Inlet and Smiths Creek. Cairns flying boat maintenance base was equipped with various types of water craft such as crash boats, bomb barges and fuel barges. RAAF crash boats were on the ready day or night to attend to the many emergencies arising from the continuous activity that went on in Trinity Inlet and Smiths Creek. Catalinas taking off on missions were usually loaded to capacity with fuel in the wing. They also carried 6000 lbs of bombs, or two 1600 lb parachute mines, or two 2000 lb torpedos. The bomb dump was located on a cane farm at Sawmill Pocket near Edmonton.

In July 1944 No.11 Squadron moved from Cairns to Rathmines, the major RAAF Catalina base on Lake Macquarie near Newcastle, separating the two squadrons after serving together for almost four years. In September No.20 Squadron moved from Cairns to Darwin, ending Cairns association with the Catalinas. Flying boat duties in Cairns were taken up by RAAF No.41 Squadron with Martin Mariner aircraft.

A post-war review of airfield requirements in January 1946 indicated the Cairns flying boat base was to continue as a RAAF responsibility. However, flying boats have long since disappeared from Trinity Inlet.


Pearce, Howard (contributing author).

Vera Bradley. I Didn’t Know That: Cairns and districts Tully to Cape York, 1939–1946, Service personnel and civilians, Boolarong Press, Brisbane, 1995.

Peter Nielsen. Diary of WWII North Queensland, Nielsen Publishing, Gordonvale, 1993.

Howard Pearce. WWII: NQ: A cultural heritage overview of significant places in the defence of north Queensland during World War II. Environmental Protection Agency, Brisbane, 2009.

Roger Marks, Queensland Airfields WW2: 50 years on, Brisbane, 1994.