SpaceShipTwo co-pilot initiated error causing crash – NTSB
The test flight of SpaceShipTwo over the Mojave Desert in October 2014 was part of Virgin Galactic's efforts at space tourism, though the National Transportation Safety Board (NTSB) found that safeguards must be included in the company's future plans.
NTSB investigators said Tuesday that SpaceShipTwo broke apart 47,000 feet over the desert -- killing co-pilot Mike Alsbury and severely injuring pilot Pete Siebold -- seconds after it separated from its carrier plane, WhiteKnightTwo. Alsbury prematurely unlocked the brakes, which are designed to "feather" the wings to slow the ship's descent.
NTSB had correctly anticipated the cause of the crash just days after the incident.
The feathering system should not have activated until a second lever was pulled, but since the system was unlocked as the ship was hitting transonic speeds, aerodynamic force caused the system to open too early, NTSB said, causing the shattering of the craft in mid-air.
NTSB board members said the braking system lacked safeguards to compensate for human error. Scaled Composites, the company that developed the ship for Virgin Galactic, "put all its eggs in the basket" of the crew executing without flaw the craft's operation, NTSB's Robert Sumwalt said Tuesday at a meeting of agency board members.
"My point is that a single-point human failure has to be anticipated," Sumwalt said. "The system has to be designed to compensate for the error."
NTSB correcting a finding approved earlier: no evidence of damage to SS2 prior to inflight breakup, not impact.— Jeff Foust (@jeff_foust) July 28, 2015
Virgin Galactic said its next version of SpaceShipTwo will come with an “automatic mechanical inhibit” to keep the braking system from prematurely locking or unlocking.
NTSB added that vibrations inside the cockpit -- which were not part of the crew's training sessions -- "could have increased the co-pilot's stress," causing the error. NTSB found that training materials offered to the crew did not sufficiently warn of risks associated with unlocking the braking system too early.
Pilot Siebold -- who survived a ten-mile fall back to the ground -- told NTSB that he did not know at the time that Alsbury had activated the braking system. Virgin Galactic promised "challenge-and-response" callouts will be added to cockpit procedures in the future.
We thank the @NTSB for their professionalism, expertise, and insight, and we welcome the results of their investigation.— Virgin Galactic (@virgingalactic) July 28, 2015
Acting NTSB chairman Christopher Hart said Tuesday that the accident will likely alter how the Federal Aviation Administration regulates the nascent industry of commercial spaceflight, though he added that NTSB is "not a regulator."
“It is our objective … to identify actions that the FAA and the industry can take to collaboratively improve the safety of commercial spaceflight in the future,” Hart said.
The failed October flight was the fourth for SpaceShipTwo. Virgin Galactic was hoping to begin the first commercial flights as early as spring 2015. Now, the company hopes to resume test flights later this year.
SS2’s predecessor, SpaceshipOne, went to the edge of space and back twice in the space of two weeks ten years ago. However, it was smaller and could only accommodate two astronauts, not enough to make it commercially viable.
SS2 is designed to carry six paying passengers and two pilots up to the edge of the earth’s atmosphere – 62 miles above Earth – so they can experience weightlessness and see the earth’s hazy blue atmosphere. The starting price is $250,000.
The project has been beset by delays since it was launched in 2004, and has hit financial difficulties after $400 million in funding from Abu Dhabi dried up. Virgin Group has reportedly had to pay day-to-day expenses itself.