Pilot actions examined in US crash of Virgin Galactic space

Investigators from the National Transportation Safety Board (NTSB) look at wreckage from the crash of Virgin Galactic's SpaceShipTwo near Cantil, California November 2, 2014. [Photo/Agencies]

Hart told a news conference on Sunday that investigators had determined SpaceShipTwo's tail system was supposed to have been released for deployment as the craft was traveling about 1.4 times the speed of sound. Instead, the tail section began pivoting when the vehicle was flying at Mach 1, the speed of sound.

"I'm not stating that this is the cause of the mishap. We have months and months of investigation to determine what the cause was," Hart said.

Asked if pilot error was a possible factor, Hart said: "We are looking at all of these issues to determine what was the root cause of this mishap ... including that possibility."

Also unclear was how exactly the tail mechanism, once it was unlocked, began to rotate, since that maneuver requires a separate pilot command that was never given, Hart said. This raised questions about whether the craft's position in the air and its speed somehow enabled the tail section to swing free on its own.

SpaceShipTwo was released normally from the carrier jet WhiteKnightTwo at an altitude of about 45,000 feet. The rocket motor, fueled for the first time in flight with a new plastic-based propellant formula, then ignited as planned, Hart said.

SpaceShipTwo's fuel tanks and engine were recovered intact, indicating there was no explosion. "The engine burn was normal up until the extension of the feathers," Hart told reporters.

About 800 people have paid or put down deposits for a ride into space at $250,000 a seat, and Branson plans to be on the first commercial flight with his son.

Branson said Monday his company's venture was "absolutely" worth the risks. "It's a grand program, which has had a horrible setback, but I don't think anybody... would want us to abandon it at this stage," he told NBC.

Virgin Galactic is about two-thirds finished building the second of its five planned space tourism vehicles, and was determining how the crash probe would alter its production schedule, chief executive George Whitesides told Reuters.

Virgin Galactic is a U.S. offshoot of the London-based Virgin Group founded by Branson, whose empire ranges from airlines to music stores and mobile phones.