How do you Grav Jump in Combat?

[OGPG]

Many times the game has mentioned that if you are in trouble you can just Grav jump away, but when I try it says "You cant Grave Jump in Combat".
So which is it? Can you or not.
If so, how?

[Sinister]

just add power to grav drive,open map pick a system and press a then (short hold) x should jump based on how much power is in the drive.

[Lt_Sid8]

it's really weird. sometimes it works, sometimes it doesn't. i'm not sure what rules apply here to make it work

[TheLoveMummy]

Your jump target needs to be in a different system and your drive cant get damaged before you jump. Move all power to shields and drive and say 10 Hail Todds.