The crash of a Virgin Galactic spaceship last year was caused by a catastrophic structural failure triggered when the co-pilot unlocked the craft's braking system early, according to federal safety investigators.
The National Transportation Safety Board began its hearing Tuesday on what caused the spaceship to break apart over the Mojave Desert during a test flight 10 months ago. The accident killed the co-pilot and seriously injured the pilot, who told investigators he was thrown clear of the disintegrating aircraft in mid-air and was not aware that the breaking system had been prematurely unlocked.
The resulting aerodynamic forces caused the brakes to actually be applied, after it was released as planned from its mother ship at about 50,000 feet, without any further action by the crew, investigators told the board. Investigators also said no safeguards were built into system to overcome the error of the co-pilot.
In determining the probable cause of the accident, board members were focused on prioritizing the lack of systems put in place to mitigate or overcome human error. Scaled Composites developed the craft for Virgin Galactic, and NTSB member Robert Sumwalt said the company "put all its eggs in the basket" of the crew doing everything correctly.
"My point is that a single-point human failure has to be anticipated," Sumwalt said. "The system has to be designed to compensate for the error."
NTSB Chairman Christopher Hart said he hoped the investigation will prevent such an accident from happening again. He said the NTSB learned "with a high degree of certainty the events that resulted in the breakup."
"Many of the safety issues that we will hear about today arose not from the novelty of a space launch test flight, but from human factors that were already known elsewhere in transportation," Hart said.
SpaceShipTwo has been under development for years and has suffered previous setbacks. In 2007, an explosion killed three people on the ground and critically injured three others during a ground test in the development of a rocket engine.
The test flights about 90 miles north of Los Angeles were part of a plan to fly tourists to the edge of space. Virgin Galactic, owned by billionaire Richard Branson, has been proceeding with its plans for space flight and is now building another craft.
Company officials have said in recent months that their commitment to commercial spacecraft has not wavered despite the crash and they expect the company to resume test flights later this year. Eventually, the company envisions flights with six passengers climbing more than 62 miles above Earth.