Enthusiasts want to recover the Sunderland Flying Boat which was caught in a storm off Pembroke Dock in 1940.
The grant covers the cost of a seabed survey to see if recovery is possible.
The Sunderlands played a key role in the Battle of the Atlantic and Pembroke Dock became the largest flying boat station in the world.
The Mark 1 Sunderland based at the former RAF Station sank without casualties in a gale in 1940 and was only discovered by divers decades later under 60ft (18.3m) of water.
William McNamara, chairman of the Sunderland Trust, said the grant was "crucial" to their plans to have the aircraft put on display.
"Sunderlands are among the most famous aircraft ever to fly with the RAF and Pembroke Dock operated the type for nearly 20 years," he added.
"This town became the largest flying boat station in the world and this is the location where the remarkable story of the flying boats and their key contribution to the Battle of the Atlantic in World War II should be told.
"This funding allows us to survey the whole aircraft and the surrounding seabed and assess how it can be recovered in the future."
Jennifer Stewart, Heritage Lottery Fund manager for Wales, said: "I'm delighted that this award will enable the project team to move plans forward in telling the fascinating story of Sunderland flying boats."
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