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 The untimely engagement of the tail mechanism, designed to slow
the vehicle's descent into the atmosphere from space, and the
possibility that pilot error was to blame, were disclosed by the
National Transportation Safety Board (NTSB) late on Sunday and have
emerged as a main thrust of the inquiry into Friday's crash.
"We know already from having the lever move from lock to unlock that
we need to get a human-factors person in here," said NTSB Chairman
Christopher Hart. "The question then is why did that happen when it
happened?"
Investigators have yet to determine whether releasing the tail
mechanism too early caused or contributed to the crash of the space
plane near the Mojave Air and Space Port, about 95 miles (150 km)
north of Los Angeles, Hart said in an interview.
The suborbital rocket vehicle dubbed SpaceShipTwo broke into pieces
over California's Mojave Desert and crashed shortly after its
separation from the special jet aircraft that carries it aloft for
its high-altitude launches.
The crash, which unfolded without SpaceShipTwo catching fire or
exploding in flames, came on its fourth powered test flight, the
first since January.
 Video footage from the cockpit shows co-pilot Michael Alsbury, 39,
who died in the crash, releasing a lever to unlock the twin-tail
section eight seconds after SpaceShipTwo’s engine ignited, Hart told
reporters on Monday night.
Two seconds later the tail, which did not have sufficient
aerodynamic pressure to hold it in place, began to pivot upward, a
maneuver designed to increase drag for atmospheric re-entry.
MYSTERY OF PILOT'S SURVIVAL
Investigators also are trying to determine how surviving pilot Pete
Siebold, 43, managed to get out of the rocket plane and parachute to
the ground from a height of roughly 50,000 feet, an altitude
virtually devoid of oxygen.
Hart said Siebold, now hospitalized with a shoulder injury, did not
exit through the cockpit's escape hatch. "We know it wasn't through
there, so how did this pilot get out?" he said.
SpaceShipTwo, developed by the fledgling space tourism company of
billionaire entrepreneur Richard Branson, was designed to carry
wealthy passengers on short rides into space, with Virgin Galactic
planning to begin offering its first flights to paying customers
next spring.
The crash came three days after the unmanned rocket of another
private space company, Orbital Sciences Corp <ORB.N>, exploded
during liftoff from a commercial launch pad in Virginia on a
mission, under contract with NASA, to deliver cargo to the
International Space Station.
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Hart told a news conference on Sunday that investigators had
determined SpaceShipTwo's tail system was supposed to have been
released for deployment as the craft was traveling about 1.4 times
the speed of sound. Instead, the tail section began pivoting when
the vehicle was flying at Mach 1, the speed of sound.
"I'm not stating that this is the cause of the mishap. We have
months and months of investigation to determine what the cause was,"
Hart said.
Asked if pilot error was a possible factor, Hart said: "We are
looking at all of these issues to determine what was the root cause
of this mishap ... including that possibility."
Also unclear was exactly how the tail mechanism began to rotate once
it was unlocked, since that maneuver requires a separate pilot
command that was never given, Hart said.
This raised questions about whether the craft's position in the air
and its speed somehow enabled the tail section to swing free on its
own.
About 800 people have paid or put down deposits for a ride into
space at $250,000 a seat. Branson plans to be on the first
commercial flight with his son.
Branson said Monday his company's venture was "absolutely" worth the
risks. "It’s a grand program, which has had a horrible setback, but
I don't think anybody ... would want us to abandon it at this
stage," he told NBC.
(Additional reporting by Susan Heavey and Doina Chiacu in
Washington; Writing by Steve Gorman; Editing by Gareth Jones, James
Dalgleish, Ken Wills and Sharon Bernstein)
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