The pilot of the Virgin Galactic commercial spaceship that tore apart during a test flight over the Mojave Desert last month says he didn't know his co-pilot had prematurely unlocked the brakes, despite protocol requiring the co-pilot to announce that step.
Co-pilot Mike Alsbury could be seen on inflight video unlocking the tail feather braking system. But pilot Peter Siebold told the National Transportation Safety Board he wasn't aware Alsbury had done so. It's not clear if Siebold didn't hear Alsbury make the announcement, or if Alsbury never said it. NTSB spokesman Eric Weiss said the safety board plans to analyze audio from the flight starting next week.
Seconds later, SpaceShipTwo began to break apart and Siebold was flung from the vehicle. He told investigators he unbuckled from his seat at some point during his fall that began miles above Earth, and his parachute deployed automatically.
Alsbury did not survive the crash.
Investigators have not revealed the exact altitude of the breakup, but previous SpaceShipTwo test flights peaked at about 10 miles. That height is well below the company's goal of sending commercial flights about 62 miles up for a fleeting sense of weightlessness and a spectacular view of Earth.
While the full investigation could take up to a year to complete, NTSB Acting Chairman Christopher Hart has already identified the vehicle's unique "feather" braking system as a possible culprit. The twin tails, or feathers, were designed to tilt upright to create drag as the vehicle reenters the atmosphere for its return to Earth.
Engaging the feathering system is a two-step process. A pilot must first unlock the system and then pull a lever to activate the feathers.
The feathers aren't supposed to be unlocked until the craft reaches Mach 1.4, or more than 1,000 mph. During the doomed flight, the system was unlocked before the vehicle reached Mach 1.0, Hart has said. The second step to activate the feathers was never taken, but the system engaged anyway. Two or three seconds later, the craft began to break apart.
The NTSB has said the feathers could have deployed because of aerodynamic forces on the craft. The agency said Wednesday that it continues to look into the forces on the vehicle. Federal officials also said they are reviewing safety documentation and the design of the feather system.
In an interview last week, Virgin Galactic CEO George Whitesides said the company has been building another spaceship and wants to resume test flights as early as next summer. The eventual goal is to launch flights carrying six passengers, each paying $250,000 for the ride, from a spaceport in New Mexico.