slam_dunk
I may well be the victim of an urban legend, but this explanation has been given to me by three separate unrelated people. None of whom was a 747 captain it must be said, and it obviously doesn't apply to 737s - no doors !.
First time I saw it (a 767), I just said hmmm and let it go. But it's intrigued me ever since the MIA episode. I had a clear view of the departure path as we loaded. A Springbok took off immediately followed by Iberia (both -200s I think), both left the gear down and both climbed at a very shallow rate. I watched them out of sight and doubt either got much above 3000ft in that time, wheels still dangling. This (extra drag) reasoning made more sense to me than the brake cooling one, but I would certainly welcome a definitive explanation.
[This message has been edited by PaperTiger (edited 28 June 2001).]