The body of 52-year-old Robert Lithgow, known as the "flying pastor" from Torquay, was found the next day tangled in parachute strings.

Bruce Ottoway, however, was never seen again.

In the years that followed, there were claims and counterclaims of pilot error and an extraordinary allegation - found to be false - that one of the men faked their own death.

But the biggest barrier to finding truth was that no one actually saw what happened.

"After Mr Evezard lost sight of the paraglider no one knows precisely what occurred," Coroner Phillip Byrne said in findings handed down last week.

On May 18, 2013, father-of-four and part-time pastor Robert Lithgow was instructing Bruce Ottoway, a 66-year-old retiree from Victor Harbor, and a second man, Peter Evezard, in hang gliding .

But first Mr Lithgow, an experienced pilot, took Mr Ottoway for a joy flight in a tandem paraglider from Flaxman Hill near Nirranda.

The last Mr Evezard saw of them from his position on the clifftops was when they flew east and out of sight after about 30 minutes.

Mr Evezard told investigators Mr Lithgow had radioed to tell him conditions were good and he should "come up".

But rain and variable winds set in and, sheltering in his car, Mr Evezard continually tried to make contact with Mr Lithgow to check if they were OK.

Searching the Hang Gliding Federation Australia website, Mr Evezard noticed a warning to Flaxman Hill flyers that there were no beach landings to the east and advice to not fly off sheer cliffs if the wind was light or likely to drop off.

He contacted Rob Van Der Klooster, then the federation's contact for Flaxman Hill, who raised the alarm with emergency services and the doomed search began.

In his findings, Mr Byrne said bad weather most likely caused the accident, despite a request from Mr Ottoway's son Arron to find that Mr Lithgow was negligent and responsible for the death of his father.

"I am not comfortably satisfied Mr Lithgow intentionally undertook a potentially dangerous course putting himself and his passenger in danger. I reiterate he may have been a victim of weather events," Mr Byrne said.

In a letter to the coroner, Arron Ottowoy said the hang gliding federation had also been negligent in the management of Mr Lithgow, who had been subject of a previous complaint from a trainee.

"Had I clear evidence of recklessness, or even failure to comply with operational standards, a wider investigation of these matters would have been permissible, but no compelling evidence of such is available," Mr Byrne said.

Mr Lithgow's wife strongly defended her husband, but also made an extraordinary claim that Mr Ottoway orchestrated his own disappearance to form a new identity.

"One can understand Ms Lithgow's grief following the death of her husband which obviously has deeply impacted upon her," Mr Byrne said.

"Being as sensitive as I believe I can in the circumstances, I reject Mrs Lithgow's contention as fanciful at best, inflammatory at worst."

He strongly supported a recommendation that all pilots carry personal GPS trackers and emergency location beacons.

Mr Byrne said an investigation by a former federation member into the previous complaint against Mr Lithgow was substandard, but it did not contribute to the deaths.

He said an online reporting incident system had been developed in response, "which should reduce the prospect of suboptimal management in the future".