The Jetpack - UAPv2.0 Readme
*****The Jetpack - probably the funnest thing in this patch... To activate your jetpack, simply turn on your field light. Once activated, you can fly by jumping, crouching, and walking; there are no seperate keys to bind!!! Also, if you die while your jetpack is turned on (i.e. you get shot out of the sky) your jetpack will explode.
NOTE : There is a bug concerning the jetpack and the bryar grappling hook. If you turn on your jetpack, then use your grappling hook; you will have to turn off your jetpack, then turn it back on before you can fly again. This is one of the things which I plan to fix in version 2.5.