The pilot is a man named Sterling (who you find in a Gittish prison, the Goretress) and the copilot is a perky child-like faerie, Stella (who you find in Angel falls after finding the ghost of Erinn's father). During the events of Dragon Quest IX, the train crashes and the hero finds it on the way to the pass with Ivor. It must be rejuvenated by there being a Celestrian on board in order to fly again. Once you beat the game (and after completing Quest 39), Sterling gives you complete ownership of the train, and the hero can travel anywhere.