Virgin Galactic pilot Todd Ericson and NTSB investigators at SpaceShipTwo accident site. Credit: NTSB

Virgin Galactic pilot Todd Ericson and NTSB investigators at SpaceShipTwo accident site.
Credit: NTSB

The National Transportation Safety Board (NTSB) is releasing today the findings of its 9-month investigation into the crash of the SpaceShipTwo late last year.

According to the NTSB, the probable cause for the mishap is as follows:

“The National Transportation Safety Board determines that the probable cause of this accident was Scaled Composites’ failure to consider and protect against the possibility that a single human error could result in a catastrophic hazard to the SpaceShipTwo vehicle. This failure set the stage for the copilot’s premature unlocking of the feather system as a result of time pressure and vibration and loads that he had not recently experienced, which led to uncommanded feather extension and the subsequent aerodynamic overload and in-flight breakup of the vehicle.”

Video shown during NTSB Board Meeting on in-flight breakup of SpaceShipTwo near Mojave, California.

Published on July 28, 2015

Scaled Composites SpaceShipTwo Powered Flight #4

https://www.youtube.com/watch?v=Qv8Y0aMNix8

Report from Virgin Galactic/The Spaceship Company

A submission to the NTSB by Scaled Composites, LLC’s SpaceShipTwo, by Virgin Galactic, LLC and The Spaceship Company (TSC) , LLC. highlights a number of items from their perspective.

According to the document provided to the NTSB, at the loss of data, multiple onboard and offboard video and data sources documented SpaceShipTwo entering an accelerated, high-g pitch up that telemetry confirmed exceeded the vehicle’s structural design loads.

SpaceShipTwo broke up into several large pieces that impacted terrain over a five-mile area near Koehn Dry Lake, California.

This photo shows pilot Pete Siebold following the SpaceShipTwo’s mid-air destruction as he parachutes safely down to Earth, with his arm up in the air to show everybody that he is alive and well. Image by Mark Greenberg/Virgin Galactic

This photo shows pilot Pete Siebold following the SpaceShipTwo’s mid-air destruction as he parachutes safely down to Earth, with his arm up in the air to show everybody that he is alive and well.
Image by Mark Greenberg/Virgin Galactic

 

A comprehensive investigation by the NTSB using telemetered and recovered onboard data conclusively demonstrated that all vehicle systems were operating normally up until the point of breakup.

The rocket motor met or exceeded expectations, running smoother and with less vibration than during any previous powered flight.

Courtesy: NTSB

Courtesy: NTSB

Probable cause

Regarding a probable cause and contributing causes, the report explains:

The probable cause of this accident was the copilot’s unlocking of SpaceShipTwo’s feather locks at 0.92 Mach, approximately 14 seconds prior to the flight manual minimum speed of 1.4 Mach.

Although normal checklist procedures maintained the feather locks in the locked position until after obtaining a minimum speed of 1.4 Mach, the mishap copilot prematurely unlocked the system at approximately 0.92 Mach.

Courtesy: NTSB

Courtesy: NTSB

This premature unlocking was indisputably confirmed by telemetric, in-cockpit video and audio data. At this speed, lift from the horizontal tails well exceeded the feather actuator’s ability to prevent a rapid aerodynamic extension of the feather system.

 

Feather unlocked position. Courtesy: NTSB

Feather unlocked position.
Courtesy: NTSB

 

These forces caused the feather to rapidly extend without any further pilot action or mechanical malfunction.

Actions taken

Following the accident, Virgin Galactic and TSC undertook a comprehensive internal and external program review of the SpaceShipTwo design and operations. Virgin Galactic recommends these actions:

1) Modify the SpaceShipTwo feather lock system with an automatic mechanical inhibit to prevent unlocking or locking the feather locks during safety-critical phases of flight.

Status: Completed

2) Add to the SpaceShipTwo Normal Procedures checklist and Pilot’s Operating Handbook an explicit warning about the consequences of prematurely unlocking the feather lock.

Status: Completed

3) Implement a comprehensive Crew Resource Management (CRM) approach to all future Virgin Galactic SpaceShipTwo operations in a manner consistent with the pre-existing CRM program VG has employed for WK2 operations. This includes, as a minimum:

• Standardized procedures and call outs

• Challenge/response protocol for all safety-critical aircrew actions, to include feather lock handle movement

• Formalized CRM training

Status: Completed

4) Conduct a comprehensive internal safety review of all SpaceShipTwo systems to identify and eliminate any single-point human performance actions that could result in a catastrophic event.

Status: An initial assessment was completed and modifications to SS2-002 are in progress. Virgin Galactic will continually evaluate and improve System Safety throughout SpaceShipTwo’s lifecycle.

5) Conduct a comprehensive external safety review of Virgin Galactic and The Spaceship Company’s engineering, flight test and operations as well as SpaceShipTwo itself.

Status: Initial Assessment Completed. The external review team will review the program both prior to commencement of flight test activities as well as prior to entering commercial service.

6) Ensure Virgin Galactic employs pilots who meet or exceed the highest standards and possess a depth and breadth of experience in high performance fighter-type aircraft and/or spacecraft. Minimum VG qualifications during the flight test program shall be:

• A long course graduate of a recognized test pilot school with a minimum of 2.5 years post-graduation experience in the flight test of high performance, military turbojet aircraft and/or spacecraft.

• A minimum of 1000 hours pilot in command of high performance, military turbojet aircraft.

• Experience in multiengine non-centerline thrust aircraft

• Experience in multi-place, crewed aircraft and/or spacecraft

Status: Completed. All current Virgin Galactic pilots exceed the above minimum VG standards.

SpaceShipTwo wreckage. Courtesy: NTSB

SpaceShipTwo wreckage.
Courtesy: NTSB

 

 

 

 

A statement from Virgin Galactic’s leader, Richard Branson, titled “The end of NTSB’s investigation and the future of Virgin Galactic” is available here:

http://www.virgin.com/richard-branson/the-end-of-ntsbs-investigation-and-the-future-of-virgin-galactic

Courtesy: NTSB

Courtesy: NTSB

Note: The NTSB findings have been issued today, a multi-month assessment of human factors, regulatory issues, technical problems found in the SpaceShipTwo program, and other concerns.

For NTSB documents regarding the SpaceShipTwo mishap, go to:

NTSB document that provides an overview of the October 31, 2014 destruction of SpaceShipTwo

http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BMG_abstract.pdf

— Opening Statement – NTSB Chairman Christopher A. Hart

http://www.ntsb.gov/news/speeches/CHart/Pages/hart_20150728o.aspx

— Investigator-in-Charge Presentation – Lorenda Ward

http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BMG_IICpresentation.pdf

— Human Factors and Organizational Issues , Human Performance Presentation – Dr. Katherine Wilson

http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BMG_HumanPerformancePresentation.pdf

— Hazard Analysis and Waivers, System Safety Presentation – Mike Hauf

http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BMG_SystemSafety_presentation.pdf

For an entire video replay of the NTSB Board Meeting regarding the commercial space launch accident – SpaceShipTwo — recorded on July 28, 2015, go to:

http://ntsb.capitolconnection.org/072815/ntsb_archive_wmv.htm

 

 

2 Responses to “Details Emerge on SpaceShipTwo Accident, Actions Taken (Updated with NTSB Documents/Photos/Videos)”

  • BillWalker says:

    Many thanks, Leonard.

  • Awesome website you have here but I was wanting to know if you knew of any forums that cover the same topics talked about here? I’d really love to be a part of group where I can get comments from other knowledgeable people that share the same interest. If you have any suggestions, please let me know. Many thanks!

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