(CNN) -- The surviving pilot of Virgin Galactic SpaceShipTwo told authorities he was unaware the feather system had been unlocked early by his co-pilot. 

The spaceship disintegrated 45,000 feet above the Mojave Desert on October 31, killing co-pilot Michael Tyner Alsbury and injuring co-pilot Peter Siebold, who managed to parachute to the ground. 

Siebold was interviewed last week by the National Transportation Safety Board. He described being "extracted from the vehicle as a result of the break-up sequence and unbuckled from his seat at some point before the parachute deployed automatically," according to a release from the NTSB. 

Earlier this month, the NTSB tweeted that Alsbury "moved the lock/unlock handle into unlock position." 

...the copilot, who was in right seat, moved the lock/unlock handle into unlock position; he did not survive accident. #SpaceShipTwo 

But that mishap alone doesn't explain why the feathering started, since no one moved the feathering handle. 

During feathering, two pieces on the back of the vehicle -- the "feathers" -- lift up perpendicular to the spaceship, making the vehicle look as though it's arching its back as it descends. 

The wreckage has been recovered and will be used for follow-up examinations. 

Test pilot's workplace a cold, harsh environment 


What was the name of the spaceship?
The surviving pilot of Virgin Galactic SpaceShipTwo told authorities he was unaware the feather system had been unlocked early by his co-pilot.