NTSB: SpaceShipTwo pilot who died unlocked device early

(CNN) -- The pilot killed in the Virgin Galactic's SpaceShipTwo disaster moved an unlocking device earlier than he should have, investigators said.

But that alone might not have caused the spaceship to disintegrate 45,000 feet in the air, killing co-pilot Michael Tyner Alsbury and injuring co-pilot Peter Siebold, who managed to parachute to the ground.

While the the National Transportation Safety Board said it is "months and months away" from determining the cause, it outlined two problems involving the spacecraft's "feathering" -- a process used to slow the spacecraft down toward Earth.

In order for feathering to start, two things have to happen: someone has to unlock the feathering system, and someone has to activate the system with a different handle.

The NTSB has said the unlocking device was moved too early. On Monday night, the agency said Alsbury was the one who unlocked the feathering system.

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