Updated: Descent rudders deployed early before Virgin Galactic space plane’s crash

Virgin Galactic’s SpaceShipTwo crashed Friday after special tail “feathers” meant to increase drag deployed early, BBC reports. One pilot unlocked the feather system, but it then deployed without a command.

The feathers–large rudders that tilt up when the plane is making its descent–are designed to be unlocked and then deployed when SpaceShipTwo has hit a speed of Mach 1.4, according to Space.com. Instead, the feathers were unlocked at around Mach 1.0, which is the speed of sound. One of the pilots moved the system to unlock, but did not take the second step of deploying it.

The National Transportation Safety Board, which is conducting the investigation into the doomed flight, has not yet stated if the feathers caused the crash. On Friday, scrutiny was placed on the never-before-flown mix of fuel Virgin Galactic has used. Virgin Galactic stated on November 4 that the engine and fuel tank were recovered intact, which means that there was no explosion.

“This definitively dismisses the premature and inaccurate speculation that the problem was related to the engine or the fuel,” Virgin Galactic wrote in the statement.

The pilot that died in the crash has since been identified as Michael Alsbury. He was a pilot for Scaled Composites for 13 years. He flew SpaceShipTwo during its first-ever powered flight in April 2013. Last week’s trip was the plane’s fourth powered flight.

“Beyond his skills as a pilot – including 1600 hours of flight time in research aircraft built by his colleagues at Scaled – Mike was a dear friend and inspiring colleague to the many many friends he left behind,” Virgin founder Richard Branson wrote on his blog. “My heart goes out to his parents, his wife and children, his sister and the rest of his family and friends.”

Alsbury’s co-pilot Pete Siebold was seriously injured. Siebold is the director of flight operations at Scaled Composites.

“We are continuing to build the second SpaceShipTwo (serial number two), which is currently about 65 percent complete and we will continue to advance our mission over the coming weeks and months,” Virgin Galactic wrote in the November 4 statement. “With the guidance of the NTSB and the assurance of a safe path forward, we intend to move ahead with our testing program and have not lost sight of our mission to make space accessible for all.”

This story was updated at 9:30 p.m. to reflect an updated report that a pilot did not command the feathers to deploy. It was updated again on November 4 with a more detailed timeline of the deployment.