the 1:25 was off the top of my head as I was at home, just trying to give an opinion based on experience.
Grizzler I think you need get out of East Anglia from time to time
Not really interested in what the FAA says as I am not governed by their rules and regs.
As Turin quite rightly says it's 35mins to 1:10hr depending on conditions, I was getting it mixed up with freezing fog at -10 which is what I encountered the other day. Even ecowings will give you upto 45mins at -3 in snow. But it's all subjective anyway as it depends on the conditions at the time and they vary somewhat.
It's quite easy to get around a 747 in 15 mins with modern equipment and 1 rig either side.