With this skill, you can handle rocket-propelled vehicles in a low or no gravity environment. You are able to safely dock and land such vessels, even in space. Any sort of spaceflight is covered by this skill, although for complex maneuvers in an atmosphere, you'll need Flying. Using ships that can carry more than a dozen passengers will require Heavy Machinery.
Although non-existent like most Pilotry skills in the distant past, our space-faring future could find this skill quite valuable.