The pilot, who survived the Virgin Galactic SpaceSwo aircraft crash, remained strapped to the seat when the ship collapsed at an altitude of 50,000 feet above the California Mojave Desert on October 31.
"At some point during the free fall, pilot Peter Sibold managed to unfasten himself, which allowed his parachute to open automatically," say researchers at the National Transportation Safety Board. "He was treated for a serious shoulder injury and was discharged."
The main pilot Michael Alsbury died in the accident. Test pilots worked for Scaled Composites, which is located in Mojave, California. This firm designed and built the SpaceShipTwo and its WhiteKnightTwo launch vehicle under contract for Virgin Galactic space tourism company Richard Branson.
The cause of the accident is being investigated, but according to preliminary data, Alsbury prematurely unlocked the moving tail of the ship. Aerodynamic forces shifted the structure, known as the feather, causing its destruction. "According to the data, the main pilot did not know that the pen system was unblocked by the co-pilot prematurely," the report of the National Transport Safety Board, published on Wednesday, says.
"The description (Sibolda) of the vehicle’s movement is consistent with data from other sources in the investigation. He stated that he was thrown out of the vessel as a result of consistent destruction, after which he was able to unfasten himself from the chair before the parachute automatically opened," they added.
Virgin Galactic hoped to start commercial passenger transport in 2015.
A preliminary accident report is expected to be published this week. The final analysis may take up to one year.