Guess the real question is: At what altitude is a pressure suit required?

Was SpaceShip One pressurized? All we saw was Melville with an O2 mask.

You always see the U2 pilots with full pressure suits, but I guess that
could be because of the duration at altitude? Since Melville was only at
apogee for a few minutes, is this like us requiring O2 only if at altitude
for 30 mins?

Just noticed and was curious..