Buzzbox- you are quite right- typing in a hurry on a meter connection in Bangkok, I let my p's and q's slip! The 747 does, of course have, flaps , not slats , I'm sure the Trident people will be only too happy to point out the difference and how slats is better! To be honest, all I know is de-icing don't work with LE Flaps extended- I've never really investigated why or how it works, but I do know the air is dumped. On a Classic we did once have a LE flap freeze up which caused a 3000' go-around at LHR, but apart from that it doesn't get used more than a couple of times a year- it seems it's very rare to get ice forming on the leading edge (which you can only just see anyway), but then I don't go to Chicago in the winter!