Failure to consider human factors led to SpaceShipTwo crash, investigators find

SpaceShipTwo broke up during a rocket-powered test flight in October 2014, seriously injuring the pilot Pete Siebold and killing co-pilot Michael Alsbury.

Investigations that immediately followed the accident found that the release mechanism on SpaceShipTwo’s “feathering” system, which creates extra drag by folding the craft’s tail fins into a near-right-angle position, was unlocked before the ship had reached the correct speed of descent.

The US National Transportation Safety Board has now determined that deployment of the feathering system represents a failure by Scaled Composites to consider and protect against the possibility of human error during the deployment of the system.

According to NTSB, the feather system was to be unlocked during the boost phase of flight at a speed of 1.4 Mach. NTSB said: “The co-pilot unlocked the feather at 0.8 Mach; once unlocked, the loads imposed on the feather were sufficient to overcome the feather actuators, allowing the feather to deploy uncommanded, which resulted in the breakup of the vehicle.”