"I was expecting him to fly out from the other side of the ledge but instead there was a very distinct sound of an impact as myself, and at least 10 other jumpers watched him bounce down an almost sheer wall. The canopy appeared to be out, but it was a ball of s***. He bounced for possibly about 250 metres and came to rest on a ledge approximately 200 metres up."
Mr McDougall said Mr McCandlish was having difficulties with a new type of wing suit he had recently switched to.
"Alan was one of the fiercest wingsuit pilots on the planet when he used to fly his S-Fly wingsuit. His flights were unmatched by any other. He had recently started flying a V4 and was having troubles flying it due to the completely different styles of flying. He had made approximately 12 jumps on the suit and the last 2 jumps he seemed to get it to fly very well."
"Although he could turn on a dime in his S-Fly, he hadn't practised turning sharply on the V4. We think he impacted on this ledge, which was covered in grass. This also explains the 2-3 seconds where no one saw or heard him as the impact made no sound.
"We think that after the initial and fatal impact he either slid or rolled down this ledge and back into free fall and it was this time when we all heard and saw the impacting down to where he came to rest on the ledge."
Mr McDougall said the conditions were "perfect" and although Mr McCandlish told another jumper he was a "little tired", he wrote it was nothing out of the ordinary.
"Alan was a very experienced base jumper and a very hard-core one at that," Mr McDougall wrote.
"He knew the risks. And unfortunately in this case it was 100% human error that resulted in his death.
"I can only ask that all base jumpers please take care out there, especially the good ones, as it is now the experienced guys dying."