Ren Frew – With outside air temps at -50 and EGT’s around 400C the difference of a few degrees would be negligible. In fact, heat from outside would be more efficient reducing the bleed requirement from the engines as the cabin has to be heated at altitude. Bodies on board do a lot of that too. Flew a nearly empty aeroplane to India recently and the cabin was unable to be controlled above 22C!

Bemused – Groundspeed may be 400-600kts but IAS and therefore the air across the fuselage has a maximum of about 360kts. At altitude IAS is more like 250kts.

How about the shiny clear laquer of American? I remember them saying at Renton the aircraft weighs more like that than it would if white or some other colour.