Obituary: Ray Grayston, RAF flight engineer

Flying Officer Ray Grayston, Member of 617 Squadron and part of the Dambuster raid. Born: 13 October, 1918, in Surrey. Died: 15 April, 2010, in Lincolnshire, aged 91.

RAY Grayston was a member of one of the most courageous squadrons of the RAF that flew on the hazardous mission to bomb the Eder Dam on the River Weser, during the Second World War. Their exploits were immortalised in the 1955 film The Dambusters in which Richard Todd played Wing Commander Guy Gibson.

The raid made use of the innovative "bouncing bombs" designed by Barnes Wallis and demanded pinpoint accuracy from both the pilots and the crews.

Grayston was the flight engineer on Les Knight's Lancaster bomber, which successfully breached the Eder Dam on 17 May, 1943. Apart from the huge technical demands, the crews also had to contend with mist and fog over the Eder lake on the night of the attack.

The dam was barely visible and was well camouflaged by the surrounding high ground with precipitous ridges. The objective was to breach the dams and flood the industrial Ruhr valley. The mission's success proved a turning point in the war and a huge morale boost for Britain..

Raymond Ernest Grayston was an automobile engineer when he volunteered for the RAF in February 1940. Initially, he trained as an aircraft engineer, but in August 1942 he volunteered for the post of a flight engineer. With a few hours flying time, Grayston teamed up with Les Knight an eager pilot from Australia. The training was brief but thorough and by May 1943 the squadron was put on stand-by for one of the most daring missions of the war.

Grayson's role was vital to the success of the mission. He sat beside the pilot in the cockpit and controlled the throttles on take-off and landing. In addition, he monitored the engines in flight.

The squadron was part of Operation Chastise, their primary aim was to breach the Mohne Dam while Squadron 617 flew to bomb the Eder Dam.

It was a tremendously challenging attack as crews had to dive steeply into the gorge that formed the Eder lake before performing a steep turn towards the dam itself. They then had to fly towards the target at precisely 60ft above the lake at exactly 230mph and release the famous Barnes Wallace hydrostatic bouncing bombs that literally bounced – like a skipping pebble – over the surface of the lake until it exploded on the dam.

After several unsuccessful attacks without breaching the dam, the mission depended on Knight and Grayston. With their last bomb, they hit the dam at its most vulnerable spot. With a huge explosion the Eder Dam disintegrated beneath them.

Four months later, Grayston was on a mission to attack a canal joining the Ruhr to the North Sea. Again, conditions were poor – there was dense fog around the target area and while reconnoitring the target Grayston's bomber hit some trees that badly damaged two engines.

The 12,000lb bomb was jettisoned, and Knight and Grayston managed to manhandle the aircraft up to 1,400ft so that the crew could bail out. Knight, bravely, remained at his post and Grayston parachuted to safety. He watched in despair as Knight crash-landed the plane. which exploded instantly. Grayston landed safely but was captured and spent the rest of the war as a prisoner.

After the raid, Grayston was commissioned and decorated by King George VI at Buckingham Palace. He was a retiring, modest man who never courted celebrity. He remained mindful of the friends who had perished on the Dambusters raid and the poignant "God bless" he heard from Knight as he made his parachute jump.

Grayston joined Hawker Siddeley at Dunsfold and worked on the Hunter, Harrier and Hawk aircraft as a quality inspector. He retired in 1984 as chief inspector at British Aerospace (Military Division), based at Kingston and lived in Lincolnshire, the centre of wartime bombing operations.

In 2003, during filming for a television programme, he flew in a refurbished Lancaster on a similar flight path (and in daylight) that he had flown half a century before. He confessed afterwards that he had "no idea how we did it. It was an adventure …we had a job to do and that was all there was to it".

In 2008, Grayston joined the veterans of Squadron 617 to celebrate the 65th anniversary of the heroic raid. The artist Robert Taylor painted a thrilling account of the dramatic events inside the cockpit after the bomb had been released with Knight and Grayston wrestling with the controls to clear the exploding dam.

Ray Grayston is survived by his wife, Sylvia, and their son.