Following a February 2019 spaceflight, VSS Unity began to undergo modifications in preparation for commercial service; this includes an upgrading the flight deck and installing a passenger cabin. It was later revealed in 2021 that VSS Unity had actually suffered a large crack in its structure during its 2019 spaceflight, requiring repair work to the vehicle. Following its return to service VSS Unity made a test flight that included Richard Branson as a passenger on July 11, 2021. During this flight, the vehicle deviated from its planned flight course triggering a Federal Aviation Administration investigation into the issue. While in ascent the vehicle triggered a red warning light which indicated it had deviated from its safe flight path. On 2 September 2021, it was publicly announced that further SpaceShipTwo flight tests would be grounded by FAA mandate until the investigation was completed. The FAA cleared SpaceShipTwo flights to resume later in September, after deciding to expand the restricted aerospace around the vehicle's flight range.
