At a public meeting in Washington, D.C., this morning, the National Transportation Safety Board revealed that a combination of human error and inadequate safety measures caused the breakup and crash of Virgin Galactic's SpaceShipTwo during a test flight last October 31, killing co-pilot Michael Alsbury and seriously injuring pilot Peter Siebold.

The accident was a tragic loss of life and setback in the nascent space-tourism movement, perhaps the worst among a year of many private spacefaring setbacks. The NTSB investigation —which combined interviews, data analysis, and video telemetry from inside the cockpit— confirmed what many suspected: Alsbury prematurely unlocked the SpaceShipTwo's so-called "feathering mechanism."

Branson maintained the NTSB investigation provided Virgin Galactic "a clean bill of health."

This system, in which the rear tail assembly pivots upward to slow and stabilize the suborbital spacecraft during its descent phase, was meant to be unlocked at Mach 1.4, but Alsbury released it at a lower altitude and speed, Mach 0.92. Because this happened during the full-power climb rather than at apogee—the highest point in the vehicle's trajectory—intense aerodynamic pressure caused the feather to overwhelm its own motors, fully deploy, and then collapse, resulting in the craft's breakup. After which, Siebold's parachute activated. He survived, but with serious injuries.

When the original SpaceShipOne was revealed in 2003, designer Burt Rutan, the now-retired founder of aviation innovator Scaled Composites, described the daring, unconventional re-entry system as a "shuttlecock" configuration meant to create a "carefree" re-entry.