Dean810:The reason I brought up communications, and I think one of the points Choudhury was making in his book, was that if they had a way to tell the surface of their gas problem, there might have been some way the boat could have staged gas for them so they wouldn't have had to make a direct accent to the surface. The accent was what killed them. I know very little about underwater communication systems, but I think their goose got cooked when they couldn't tell the surface of their problem. By the time the boat knew what was going on, it was too late.
It's been a long time since I read the book but if I remember correctly the author was suggesting communication as a safety improvement for tech diving in general. I disagree and already outlined most of the reasons why. In the case of this dive, though, didn't they end up ascending in OW away from the line? I don't remember for sure but, if so, where wopuld the topside crew have staged extra gas? They would have to know where the divers would be comming up and they'd have to be able to get the gas ther fast to be of any help.