SpaceShipTwo Brakes Possibly Deployed Early

Miscommunication between pilots may have contributed to crash

Nov 13, 2014
Outside Magazine
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The full investigation into the SpaceShipTwo accident could take up to a year.    Jeff Foust/Flickr

Federal investigators found Wednesday that the pilot of Virgin Galactic’s SpaceShipTwo, which crashed during a test flight over California’s Mojave Desert, did not know that his co-pilot had prematurely unlocked the ship’s brakes.

According to the Associated Press, pilot Peter Siebold told the National Transportation Safety Board (NTSB) that co-pilot Mike Alsbury had pulled the lever that unlocked the brakes before the rocket was finished accelerating, but Siebold was not aware of it. An agency spokesman told the AP that protocol dictates that the co-pilot announces the unlocking, but it is unclear if Siebold didn’t hear Alsbury or doesn’t remember Alsbury telling him. In-flight video shows Alsbury unlocking the brakes before SpaceShipTwo reached Mach 1, NTSB chairman Christopher Hart told the AP. The system was supposed to be unlocked only after the ship reached Mach 1.4, where it would have been high enough that the thinner air would not have given the brakes as much resistance.

Normally, simply unlocking the brakes shouldn’t have deployed them; the crew would have had to pull a second lever to do that. But investigators think the system could have engaged anyway and contributed to the crash. Siebold and Alsbury did not pull the second lever, but the brakes deployed—possibly due to the aerodynamic forces exerted on the craft—and SpaceShipTwo began to break apart seconds later. Alsbury was killed in the crash. Siebold sustained injuries after he was thrown from the disintegrating ship but managed to deploy his parachute. He was hospitalized and released last week.

The NTSB plans to listen to the flight audio next week, but the investigation could take up to a year. According to the AP, Virgin Galactic CEO George Whitesides said the company hopes to launch more test flights next summer using a replacement craft.