I am 6' 4" and have no problem, and there are several people taller than me in my airline, so it isn't an issue in the airlines (in Australia anyway).
The RAAF does have a few height requirements as some RAAF cockpits are a bit tight. You also may be wearing a helmet (that adds a couple of inches) and sometimes a parachute. They are also concerned about the survivability of rapid (i.e. ejection seat) egress from the cockpit. RAAF requirements are not stated in standing height, but rather in terms of different body dimensions, height from seat to top of head, length from back to knee in the seated position etc. I made those requirements at 6' 4", some smaller (with differently shaped bodies) have missed out.
[ 23 August 2001: Message edited by: Checkboard ]