On this day in 2014: Virgin Galactic’s SpaceShipTwo broke apart mid-air, killing a pilot

On October 31, 2014, Virgin Galactic’s VSS Enterprise broke apart during a powered test flight over California’s Mojave Desert, killing co-pilot Michael Alsbury and injuring pilot Peter Siebold. The NTSB found that the feather locks were released at about Mach 0.8, far earlier than the Mach 1.4 the procedure required, and aerodynamic loads then extended the feather. Its probable cause was Scaled Composites’ failure to protect against a single human error creating a catastrophic hazard. The next vehicle, VSS Unity, added a mechanical inhibit to prevent premature unlocking. Twelve years on, the accident remains a key lesson in safety-critical design. Video credit: NTSBgov, Virgin Galactic, The Astronauts Memorial Foundation, NASA STI Program, GettyImages