Fwd: Update: NTSB Confirms SpaceShipTwo feathering was Prematurely Unlocked

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From: "Gary Johnson" <gjohnson144@comcast.net>
Date: November 5, 2014 7:52:54 AM CST
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: Update: NTSB Confirms SpaceShipTwo feathering was Prematurely Unlocked

 

Update: NTSB Confirms SpaceShipTwo feathering was Prematurely Unlocked

by Tim Reyes on November 4, 2014

 

NTSB Acting Chairman Christopher Hart shown explaining details of the investigation during a Monday Press Conference at Mojave Air & Space Port. (Photo Credit: NTSB)

In a Monday afternoon press conference, acting NTSB chairman Christopher Hart confirmed that the safety lock on Virgin Galactic's SpaceShipTwo feathering mechanism was prematurely unlocked moments before breakup. Hart also quickly stated that this would be the last on-site press conference. The NTSB is nearing the completion of data gathering and the team will be returning to Washington DC with the data to undertake the facts compilation followed by the analysis.

Hart reiterated that the test flight was rich in telemetry. He said that the supply of data could expedite the analysis but he cautioned that they still expect the investigation to take 12 months to conclude and release a final report. He also added that as analysis proceeds, the NTSB would provide updates and he encouraged interested parties including the public at-large to undertake analysis of the available data; however, he emphasized that the conclusions drawn would be based on NTSB analysis alone.

From the data released and statements by Hart during the press conference, it is now clear that the NTSB recognizes that the feathering was not to be deployed until SpaceShipTwo achieved mach 1.4. The statement that acting chairman Hart made appeared to be explicitly referencing the Flight Card – the plan of actions and constraints for the flight. If this was the specific wording on the flight card, then it would have permitted a pilot to interpret it in various ways.

Sunday, it was reported that SpaceShipTwo was flying at about Mach 1.2 when break up occurred. As a private pilot familiar with the impact that flight conditions have on operations of an aircraft, I would add that the SpaceShipTwo constraint of mach 1.4 for executing feathering is likely intended to be viewed by the pilots-in-control as the descent speed after SpaceShipTwo had achieved maximum altitude during a flight to the edge of the atmosphere. During descent, mach 1.4 would be achieved at a much higher altitude where the air density is much lower and stresses from the feathering would also be much lower; SpaceShipTwo is designed to feather with those environmental conditions. During previous tests of SpaceShipTwo when feathering was tested at low altitude, the vehicle was flying far below mach 1, i.e. subsonic. The vehicle in that flight regime had no difficulty withstanding stresses during the test of feathering. It should be emphasized that the strict rules under which the NTSB proceeds with an investigation does not allow the investigators to inject assumptions based on their past experience.

A timeline of events leading up to catastrophic breakup of SpaceShipTwo was stated by the NTSB acting chairman:

10:07:19: SpaceShipTwo is released from the carrier craft, WhiteKnightTwo
10:07:21  SpaceShipTwo's engine starts
10:07:29  SpaceShipTwo reaches mach 0.94
10:07:31: SpaceShipTwo exceeds the speed of sound – mach 1.02. Between 10:07:29 and 10:07:31, the feathering safety was unlocked.

10:0 7:34: All telemetry was lost

The NTSB has also created a new team responsible for evaluating the Human-Machine Interface (HMI) on SpaceShipTwo. HMI is a discipline that has gained increased interest within several manufacturing sectors, particularly in aircraft cockpit design. The performance of modern aircraft, places greater demand on human performance. The formulation of a Human performance team evaluating the HMI of SpaceShipTwo indicates that the NTSB wants to assess the quality of the cockpit control panels and whether the configuration of switches contributed to pilot error.
While most of the debris is confined to a 5 mile swath of desert, Hart stated that debris has now been found as far as 30 to 35 miles from the immediate debris field.

Besides the apparent focus by the NTSB on the unplanned feathering, Hart stated that they are checking the subsystems of the spacecraft for integrity – pneumatics, flight control, electrical and so on.

Hart concluded the press conference by taking questions from reporters.

Q. Had the pilot been interviewed?
A. Not yet and not until he is fit to be interviewed.
Q. Was the flight card reviewed?
A. The NTSB has reviewed the flight card for procedures and constraints. According to Hart, the card stated to not release the safety lock of the feathering mechanism until mach 1.4.The flight card describes the steps that a flight crew is to take to complete a successful mission.
Q/A. Hart confirmed that 2 pilot actions were necessary for feathering. 1) Unlock the safety and 2) engage feathering lever. U.T. – Hart could not say if both pilots were necessary, that is, shared the two step process.
Q/A. A reporter contentiously asked Hart who was in the right seat. Hart stated that he did not know and also was unwilling to assume that it was the co-pilot, Alsbury. The reporter probing him further asked about his statements from Sunday. Hart agreed that he was mistaken to have assumed on Sunday that it was the copilot.

Finally, a review of the NTSB press conference video, placed on YouTube, presented a clarification as text on video. It stated that the co-pilot was residing in the right seat and was responsible for unlocking the feathering. At this preliminary stage of the investigation, it would appear that Alsbury's death in the accident was due to his premature unlocking of the feathering mechanism. Hart did not state this but the circumstantial evidence so far is pointing in that direction.

Reference:

NTSB Press Conference Video, November 3, 2014 

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SpaceShipTwo Investigation Expands To Include Human Factors

By Jeff Foust | Nov. 4, 2014

 

Virgin Galactic pilot Todd Ericson (left) shares information at the SpaceShipTwo accident site with NTSB Acting Chairman Christopher Hart (right) and investigators. Credit: NTSB photo

WASHINGTON — As the U.S. National Transportation Safety Board (NTSB) wraps up the on-scene portion of its investigation into the fatal crash of SpaceShipTwo, officials said Nov. 3 that they planned to expand their work to include an analysis of human factors that may have contributed to the accident.

At a press conference held late Nov. 3 at the Mojave Air and Space Port in California, NTSB Acting Chairman Christopher Hart said investigators had established a "human performance" group to work alongside groups studying debris, data and other information about the Oct. 31 accident.

That group, Hart said, will examine "the interface between the flight crew and the vehicle, to look at issues such as displays, checklist design and other issues."

The decision to add human factors analysis to the investigation came a day after the NTSB revealed that SpaceShipTwo's co-pilot, Michael Alsbury, had unlocked the vehicle's feathering mechanism prematurely. That mechanism is designed to raise the vehicle's twin tail booms during re-entry to provide increased drag and stability.

Hart said at a Nov. 2 briefing that seconds after Alsbury unlocked the feather, it started to deploy, although the pilots had not moved the handle to engage it. Soon afterward, telemetry and video from SpaceShipTwo were lost.

According to a specific timeline of events Hart read at the Nov. 3 briefing, the feather went from locked to unlocked between eight and 10 seconds after engine ignition, as SpaceShipTwo accelerated from Mach 0.94 to Mach 1.02. "Soon after that, the feather itself soon began to deploy," he said, with telemetry cut off 13 seconds after engine ignition.

At the Nov. 3 briefing, Hart appeared to back away from statements the previous day identifying Alsbury as the pilot who unlocked the feathering mechanism. Hart said it was the pilot sitting in the right-hand seat in the SpaceShipTwo cockpit who unlocked it, but could not confirm that this person was the co-pilot.

Shortly after the briefing ended, NTSB posted on its Twitter account a clarification of Hart's comments: "[T]he copilot, who was in right seat, moved the lock/unlock handle into unlock position; he did not survive [the] accident." Scaled Composites announced Nov. 1 that Alsbury was the co-pilot of the flight and was the person who died in the accident.

The pilot of SpaceShipTwo, Peter Siebold, was injured in the accident and has not yet been interviewed by NTSB investigators. "We will work with his medical care and his family to arrange that interview when he's ready," Hart said.

Although the NTSB has stopped short of blaming the accident on the premature unlocking of the feathering mechanism, Virgin Galactic went further in a statement issued early Nov. 4.

"The NTSB indicated that the lock/unlock lever was pulled prematurely based on recorded speed at the time, and they have suggested that subsequent aerodynamic forces then deployed the feathering mechanism, which resulted in the in-flight separation of the wings and vehicle," the company said in the statement.

Virgin Galactic also said in the statement that it planned to continue construction of a second SpaceShipTwo at the company's Mojave factory. The second SpaceShipTwo is currently about 65 percent complete.

At a media tour of the factory in October, Virgin Galactic executives said that second SpaceShipTwo would be ready for test flights in 2015 and commercial service in 2016. The company's Nov. 4 statement gave no timeline for completing the vehicle.

The Nov. 3 NTSB briefing is the last planned in this phase of the investigation. "The on-scene portion of the investigation will be closing within a few days," Hart said at the briefing. The overall investigation will continue for up to 12 months, with the NTSB providing updates from Washington "as events warrant."

 

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