Sorry guys
I still can't see why Jepps don't provide "threshold" LDAs for all runways. The situations where it's just the glideslope distance that is given is pretty useless since it does not relate to anything in the ops manual (perf section) or my company's QRH. I could add an approximate 1000 ft to the glide slope distance but I'd have a hard time justifying that on a line check!
Any thoughts? Appreciate all the background info which is interesting but it's what happens on a dark and dirty night with a double hydraulic failure on a wet runway that I'm really concerned about. As someone earlier mentioned I wouldn't be happy just to take the TORA as stated. If it is that simple then why don't Jepps say so?