747FOCAL,
To quote BahraiLad's quote, the longest slide on a 747 is 46 feet! I'm sure thats just as daunting.
I do agree though that evac cetrification is a problem but in my view it's the fact that the 90sec requirement is tested with no smoke, no noise, no panic, no heat, no fire etc. I can only speak for myself but in such a senario i wouldn't give a damn if I was sliding 46 or 50 feet!