How do I move a character in the exact camera facing direction (including Y axis)?

I’m trying to make a type of simulated flying at the press of a button, and I cannot seem to get the actor to move in the Y axis. When I look left or right, the character will move in that direction, but when I look up or down, the character still stays on the ground with gravity being applied. What can I do to allow the camera to move the player on the Y axis?