Ok, this is what's known as the Airship Glitch. What you do is save your game at any point, and never save again. Get to the Floating Continent any way you can. Once there, return to the Airship and fly around for a bit without landing. Go back to the floating continent and die. It'll put you back to your last save... IN THE AIRSHIP. Even if you didn't acquire the Airship, it puts you in the Airship because the game didn't reset its checks, therefore because you died on the Floating Continent, the game assumes that you have the Airship.
As you can see above, my save was at Vector before the Magitek Factory, however, this has a twist. When I originally did the glitch, it was during Sabins' Scenario, right before the Phantom Forest (there's a reason why I picked that particular spot). Above would be the second time I did this, and it seems I have a surprise, in that Sabin has 9999 health and 999 MP. The rest of his stats remain the same. And if you are wondering, keeping your level and stats is not a glitch. It was by the games design, one you probably never noticed while playing.
However, I'm not done. By utilizing this glitch, I will pull off 2 even more Game Breaking glitches. Here's a hint: skipping the Phantom Forest was necessary in order to pull this off.