A 75-year-old death fell to his death when he failed to respond to instructions after his parachute tangled during a 3,500 feet jump.
Mr Simmons took up parachuting after his son died of cancer
Francis Simmons, 75, had been jumping from a plane at Hinton-in-the-Hedges, Northamptonshire, when the parachute lines became wrapped around his left arm.
An inquest heard on Wednesday that despite radio instructions Mr Simmons, of Conrad Road, Plymouth, never corrected the canopy and suffered fatal injuries on landing.
Deputy coroner Rodney Haig, who recorded a verdict of accidental death, said there was no explanation why this had happened.
The inquest at Northampton General Hospital was told Mr Simmons
had taken up parachuting three years ago and had carried out a number of jumps for charity after his only son died of cancer.
Instructors from Hinton Skydiving Centre, where Mr Simmons made the fatal jump on 16 April 2003, said the pensioner had told instructors he was only 64 so they would allow him to parachute from 3,500 feet.
The instructors added Mr Simmons was considered fully fit and competent to do the jump alone, having undertaken nine previous parachute jumps.
On the morning of 16 April he was given a refresher course and his equipment was fully checked.
Skydiving instructor Alex Waller said Mr Simmons left the plane without hesitation but quickly became entangled.
"He made no effort to solve the problem," he said. "When they leave the plane there is nothing you can do."
Brian Poole, a second skydiving instructor, said he had been talking on the radio to Mr Simmons as he descended.
He said despite instructions to check his canopy, he made no attempt to carry out what was an "easy manoeuvre".
Mr Simmons was taken to John Radcliffe Infirmary in Oxford where he later died of multiple injuries.
Mr Simmons's ex-wife, Lillian Webber, said he took up parachuting to raise money for Macmillan Cancer Research after their 51-year-old son died from cancer in 2000.
She said: "He was a Peter Pan, he was young at heart and took care of himself and other people."
Mr Haig said: "He was contacted by radio and given the instructions to check his canopy but he seemed for some reason to have ignored that instruction.
"There seems to be no explanation for why he did this."