What makes you think the same regional airline would hire you back if you quit? That's rather presumptuous.
I would always assume quitting a company would leave a bad taste in their mouth and possibly make you undesirable for rehire.
If you were lucky enough to come back to the same company, I would expect a brand new file to be started with no credit for tenure. That's worst case, of course, but very possible. Even if they tell you something different now, there are no promises for future policy or circumstances.
Think twice before you resign a job you may want back in the future.