Pretty much the title. If you take a jump pad and press space bar, you will slow down quickly and stop moving in the forward direction and instead move upward. Standing still versus running versus sprinting also has only an initial small difference in air momentum, but is quickly stifled.
Planetside 2 seems to use a system that normalizes your speed to a given pre-defined vector over time. It doesn't seem to have true "forces" probably for optimization purposes. The benefit is that if you bail out of a high-speed aircraft, you can safely descend without your forward momentum killing you when you land. The drawback is the behavior you describe here. It definitely reduces a lot of the jump-jet shenanigans that could occur.
Yeah, It's a bit anti-climatic playing as LA to have your whole character move at a pre-defined rate when using jets. Really limiting
