(Multi-functional Transport Satellite-based Augmentation System) A Japanese system of earth stations and satellites that improves the tracking accuracy of the GPS navigation system down to approximately six feet. Launched in 2007, MSAS is expected to cover other parts of Asia as well as Australia and New Zealand. The MSAS earth stations track the navigation satellites and send correction signals to the MSAS satellites, which transmit them to MSAS-enabled navigation systems. See GPS augmentation system and GPS.