So where does Sir Norman Foster do much of h is designing? With his head - literally - in the clouds. In fact while he is piloting his Citation from Biggin Hill to various projects, most notably in Berlin . His black sketch book is perched on his knee as he doodles at 30,000ft. Happily he always has a co-pilot sitting next to him at the controls. The practice's latest airport scheme, a long way from Chek Lap Kok, is a major terminal building . . . at Luton Airport.