NTSB Not Sure Which Pilot Moved Feather System from Lock to Unlock – UPDATE

NTSB Not Sure Which Pilot Moved Feather System from Lock to Unlock – UPDATE

UPDATE, November 4:  The NTSB subsequently tweeted that Hart misspoke at this press conference, not at the previous one, and it was indeed the SS2 co-pilot who prematurely moved the lock/unlock lever.

ORIGINAL STORY: National Transportation Safety Board (NTSB) acting chairman Christopher Hart said tonight (November 3) that he was mistaken yesterday in stating that it was the co-pilot of SpaceShipTwo (SS2) who prematurely moved the feather system’s lever from lock to unlock.  That action appears to have been a major contributor to the SS2 crash on October 31. NTSB knows it was the person in the right seat, but not which of the two pilots was sitting there.  Co-pilot Michael Alsbury died in the crash. The pilot, Peter Siebold, remains hospitalized.

Hart provided a timeline of events for the test flight in Pacific Daylight Time (PDT):

10:07:19 — SS2 released from the WhiteKnightTwo mothership
10:07:21 — SS2 engine start
10:07:29 — Mach 0.94
10:07:31 — Mach 1.02.  In that 2 second period, telemetry shows lock/unlock lever moved to unlock position.  Soon after, feather system began to deploy.
10:07:34 — telemetry and video lost

SS2 is a spaceplane that is carried aloft by an aircraft, WhiteKnightTwo.  At about 45,000 feet, it releases from the aircraft and then fires a rocket engine to take it higher.  The goal is to reach at least 100 kilometers altitude, an internationally recognized (but not legally defined) boundary between air and space.  After a few minutes, the spaceplane returns to Earth.  SS2 is owned by Richard Branson’s Virgin Galactic, which offers rides into space for anyone who can afford the $250,000 ticket price.   Passenger flights were expected to commence in 2015, but it is not clear now when that will happen.

The feather system is a unique method of slowing the spaceplane as it descends from the top of its arc (apogee).  The tail booms pivot upwards to create drag to slow it down.  Then, as the spaceplane reaches denser layers of the atmosphere, the tail booms are returned to their normal position and the vehicle glides back to Earth.

It takes two steps to engage the feathering system.  First, a lock/unlock lever must be moved from the locked to the unlocked position.  Then, a separate feathering handle must be moved to the feather position.  The first step is not supposed to take place until the spaceplane has reached Mach 1.4.

Telemetry and video from the cockpit show that one of the two SS2 crewmembers moved the lock/unlock lever to the unlock position at only Mach 1.02, however. The second step, moving the feathering handle to the feather position, never occurred, but the feathering system deployed on its own.  Investigators have not determined why the first lever was moved to the unlock position prematurely or why the feathering system deployed without the second step.

The NTSB has not interviewed the surviving pilot, Siebold.  Hart said they were working with his medical team and family to determine when that should take place.  Although Hart said definitively yesterday that it was the co-pilot (Alsbury) who moved the lever to the unlock position, he said today he was mistaken.  All they know is that it was the person in the right seat.  They cannot state for certain who was sitting there.  (Ordinarily, that is where the co-pilot would sit.)

Hart said on Saturday that debris was scattered over a 5 mile area, but today increased that significantly.  He said lightweight parts have been found as far as 35 miles northeast of the main area, though they do not know if they fell there initially or were carried there by the wind.  The NTSB is collecting all the debris and moving it to hangars for further study.  The largest piece is part of the fuselage wing and he said they would have to carefully cut it into pieces to move it.

The investigation team, headed by NTSB’s Lorenda Ward, is broken into groups and a new one was created today, the Human Performance Group, to look at the interfaces between the flight crew and the vehicle, including displays and checklists.

Hart reiterated that the investigation will take about 12 months to complete, but work on-site at Mojave, CA is nearly done and the focus will shift to the NTSB’s laboratory in Washington, DC.  In the end, the Board will issue a report with the probable cause and recommendations to prevent it from happening again.  He said this is the last on-scene NTSB press conference from Mojave.

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