For various reasons that you will encounter if you work with FPSC long enough you will discover its not really practical to attempt such as this.
Apart from anything else - vehicles, aircraft and so forth will quickly exhaust the world size during movement - you will fall out before you get your accelleration going. Of course you could go up/down and around in small circles though its not always ideal.
I guess you could fake a helicopter hovering within a small radius looking out from a cockpit - that should work quite well.
You could study the jetpack scripts and impliment something along those lines.
A lot of things can be attempted and partial success achieved, however there are serious drawbacks and resrtictions to achieving non default game functions that are likely to cause serious obstacles to many trying to achieve them.