A British coroner on Wednesday described the safety mechanism of an ejection seat that threw a pilot from the Red Arrows aerobatics display team to his death as "entirely useless".

Flight Lieutenant Sean Cunningham, 35, was killed after he was accidentally propelled 67 metres (220 feet) into the air from his Hawk T1 aircraft while on the ground at Scampton airbase outside Lincoln, eastern England, in November 2011.

The South African-born pilot remained attached to his seat and plunged to the ground after his parachute failed to deploy because of a nut and bolt fastened too tightly, an inquest into his death heard.

He sustained life-ending injuries to his brain and cardiovascular system as a result of the high-velocity impact with the ground.

The inquest, held in Lincoln, heard that the ejection seat firing handle had been left in an unsafe position, allowing it to activate the seat accidentally.

Coroner Stuart Fisher recorded a "narrative" verdict, meaning the circumstances of the death are not attributed to a named individual.

He criticised the seat manufacturer, Martin-Baker, for failing to inform the Royal Air Force of risks associated with it.

Fisher said the safety pin mechanism was "entirely useless" and that it was "likely to mislead".

Tests of the MK 10 Martin-Baker seat had showed that the safety pin could be inserted even when the seat was in an unsafe position, the coroner said.

Despite being aware of the risks since 1990, Martin-Baker had failed to warn the Ministry of Defence, the coroner added.

During the inquest the court heard parts of the ejection seat were redesigned following the Red Arrows pilot's death.

In English law, inquests are held to examine sudden or unexplained deaths. They set out to determine the place and time of death as well as how the deceased came by their death, but do not apportion blame.

In statement released after the inquest, Martin-Baker extended its "sincere condolences" to Cunningham's family and friends.

"We take our responsibilities to these individuals very seriously and we are all deeply saddened by this terrible accident," it said.

Martin-Baker said the incident was the only time in the history of the seat that such a malfunction had occurred and "lessons had been learned", leading to the re-design.

Cunningham's parents agreed an undisclosed settlement with the Ministry of Defence in December, after it admitted liability for the incident.

Speaking after the inquest, his father Jim Cunningham said: "We welcome the conclusion of the coroner which confirmed what we knew all along, which is that Sean was blameless and his tragic death was preventable."

The highly-skilled Red Arrows perform all over the world and are often seen at royal and national events, such as the London Olympics and Queen Elizabeth II's diamond jubilee celebrations in 2012.