Enduring Flight

Transmutation
Level Sky 3, sorcerer/wizard 4
Components V
Casting Time 1 full round
Range Personal
Target You
Duration See text

You can carry more weight aloft while flying, and your flight lasts longer than normal. You can fly at normal speed when wearing medium armor or carrying up to a medium load. If your ability to fly (whether natural or magical) has a limited duration, that duration is doubled. This spell lasts as long as you remain airborne, it ends the moment you land.

(RotW page 175)