On April 22, Letham undertook a recreational flight. He took off from a designated area on Bob's Peak above Queenstown, with his intended landing point being in the Queenstown Primary School grounds.
During his flight, he undertook a number of "infinity loops", an aerobatic manoeuvre in which the pilot causes himself and the canopy to rotate around a horizontal axis as if somersaulting.
Letham successfully undertook about seven of such loops but on the eighth appeared to have insufficient momentum to carry him through the completion of the loop.
Instead, he fell into the canopy, which was at that point below him. He became entrapped within the canopy with the consequence that it collapsed and could no longer function as an airfoil.
Either due to that entrapment or the proximity of the ground, he was unable to deploy a reserve chute.
He fell to his death and received multiple traumatic injuries, including; skull fractures, a fractured spine and multiple rib fractures, etc.
The injuries were un-survivable and likely to have been instantly fatal.
The death was subsequently referred to the coroner.
After an inquiry into Letham's death, coroner David Robinson ruled Letham died of multiple traumatic injuries after accidentally losing control of the paraglider.
The accident was investigated by the Civil Aviation Authority who advised the coroner that Letham had been practising the aerobatic manoeuvre for approximately three months and had been witnessed by other experienced pilots to be competent.
The infinity loop is considered as an advanced and a competition-type manoeuvre. It is generally carried out at a height above ground allowing sufficient time to recover should an in-flight emergency occur, they said.
CAA investigators concluded that the continuum of multiple infinity loops conducted over a short distance and height did not provide sufficient room for recovering from a loss of control.
Robinson said Letham's death appeared ultimately to have been due to a lack of momentum when undertaking the final loop.
He adopted the recommendation of the CAA that aerobatic flights should be conducted at a height above ground at which a pilot can manage an in-flight emergency and recover the aircraft.
A pre-flight assessment of the manoeuvres to be carried out, and the amount to be conducted, could be discussed with peers to provide an objective risk assessment, recommendations suggested.
During the manoeuvres, pilots need to maintain an appropriate level of situational awareness of their surroundings, to ensure a suitable safety margin is maintained, the CAA added.
Robinson directed to have the findings provided to the NZ Hang Gliding and Parachute Association.
"In order that the circumstances of Letham's death and the risks associated with excessive numbers of infinity loops can be highlighted", he said.
Robinson extended his deepest condolences to Letham's family and friends.
