This is a problem that will never be resolved to anyones complete satisfaction, and I gave the same answer to an oil company audit recently.
Certainly with Skycranes once you have gone up the slippery angle to the top decking, or even worse the stainless table over the engines it is deadly with thin grease coating everything.
I worked in Sarawak, logging with Bruce Harvey and hope he make a good recovery. A good man to work with.
Luckily I never fell off the Crane but thats all it was, was luck.
After years working on the Puma on logging, and swamps, I did eventually fall through down the side, feet first, after telling the Parker Drilling visitors to be careful not to fall through the exhaust hole. I hit every fitting on the way down but no real damage done.
One ex Bristow machine we had, P2 PHZ was a killer as it had locks at the front of the engine cowls, involving a 'tip toes' trip along the rain gutter. More than one person got the job out of sequence and shot off into space as the cowl opened up.