UFO Patrol - Atari - Shooter, Sci-Fi

This game has you placed in a spacecraft of some kind (the cover art makes it look like a futuristic passenger jetliner with weapons attached) flying through what looks like a cave, while taking on several enemies that attack you from the right side of the screen. After surviving a few rounds, you'll go into an 'underground' cave where you fly through a treacherous corridor and attempt to dock with a refueling station. After that, it's back to blasting targets again. Lather, rinse, repeat.