From Planetside Syndicate
The HART, or High Altitude Rapid Transport shuttle, is a large passenger spacecraft that makes regular flights at three minute intervals to any of the ten planets and their continents. Landing and departing from special platform hangars (HART buildings) in each Empire's Sanctuary.
To disembark a HART before it departs, press the use key (default G), you will appear outside of the HART doors in your sanctuary. You can "bail" (default key: alt+G) from the HART once the vehicle clears the hangar, skipping the rest of the launch animation, and enabling you to select a drop location faster.