NTSB Findings, Probable Cause and Safety Recommendations

Part of SpaceShipTwo's fuselage. (Credit: Kenneth Brown)
Part of SpaceShipTwo’s fuselage. (Credit: Kenneth Brown)

Editor’s Note: The NTSB’s official statement is here.  It’s clearer and more polished than the one below.

The NTSB approved probable cause, findings and safety recommendations regarding the crash of SpaceShipTwo during a flight test on Oct. 31, 2014. The following is based on a real-time transcript, so there may be some minor errors.

Probable Cause

Scaled Composite’s failure to consider and protect against the possibility that a single human error could result in a catastrophic hazard. 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.

17 Findings

  1. Although the copilot made the required callout at the correct point in the flight, he incorrectly unlocked the feather immediately afterward instead of waiting until SpaceShipTwo reached the required speed of 1.4 mach.
  2. The unlocking of the feather resulted in uncommitted feather operation. It was the external load on the flap assembly, greater than the capability of the feather actuators to hold the assembly in the position with the locks disengaged.
  3. The co-pilot was experiencing high workload as a result of recalling tasks from memory while performing under time pressure, and with vibration and loads he is not recently experienced which increase the opportunity for errors.
  4. The pilot and copilot were properly certificated and qualified. Fatigue, medical, and ecological issues were not factors in this accident. The recovered vehicle component showed no evidence of pre-impact system will rocket motor failures.
  5. SpaceShipTwo’s instantaneous impact point on the day of the accident was consistent with the requirements of 14 code of federal regulations, operating area containment.
  6. Although Scaled’s Composite system safety analysis correctly identified that uncontrolled feather operation would be catastrophic, the SSA process was inadequate because it allowed an and analysis that failed to dignify a single human error could lead to a problem in the boost phase and failed to boost the effectiveness of mitigation measures.
  7. By not considering human error as a potential cause of uncommitted feather extension on the SpaceShipTwo vehicle, Scaled Composite missed opportunities to identify and design operational requirements that could have mitigated the consequences of human error during a high workload space flight.
  8. Scaled Composites did not ensure that pilots correctly understood the risks of unlocking the feather early.
  9. Human factors should be emphasized in the design, operational procedures, hazard analysis, flight crew simulator training for commercial space vehicle to reduce the possibility that human error during operations could lead to a catastrophic event.
  10. The Federal Aviation Administration Office of Commercial Space Transportation’s valuations of Scaled Composite were deficient, because the evaluations failed to recognize that Scaled Composites analysis did not identify hazard caused by human error.
  11. The lack of direct communications between staff and Scaled Composite’s technical staff, the pressure to approve experimental applications within the 120-day review period, and the lack of mission safety assurance innervate — interfered with the FAA’s ability to evaluate applications.
  12. The Federal Aviation Administration Office of Commercial Space Transportation did not ensure that Scaled Composites complied with the waiver or required whether mitigations would adequately address human errors with catastrophic consequences.
  13. The experimental permit pre-application consultation process would be more effective if it were to begin during a commercial space vehicle design phase so that concerns can be resolved before a commercial space vehicle developed and manufactured a potential catastrophic hazard identified by human error could be identified early.
  14. The effectiveness of the Federal Aviation Administration Office of Commercial Space Transportation inspection process would be improved if inspectors were assigned commercial space operators, rather than individual commercial space launch operations because the inspectors could become more familiar with the operators’ training and procedures and could identify ways to enhance safety.
  15. A database of lessons learned for commercial space mishaps investigations would provide mutual benefits for the safety and industry promotion and would thus be consistent with the federal aviation administration’s mission and authority.
  16. Scaled Composites and local response officials could improve readiness for future tests by making available use of helicopter assets.
  17. Additional parachute training and procedures would have prepared Scaled Composites’ test pilot for emergencies.

10 Safety Recommendations

The staff proposes 10 new safety recommendations. There are eight to the Federal Aviation Administration.

  1. Collaboration to develop and issue guidance for operators to use for the crew in the vehicle. It should address and not be limited to the human factor issues identified in the accident investigation.
  2. Implement steps in your evaluation for experimental permit applications to make sure applicants have 1 — identified tasks that if performed incorrectly or at the wrong time could result in a catastrophic hazard. 2 — assess the reasonableness of factors that could prevent errors that result in the performing of those tasks. Three, fully document the rationale use for related assumptions in the hazard analysis from 14 federal regulations.
  3. Develop a process to determine whether an experimental permit applicant has demonstrated the adequacy of existing limitations to ensure public health and safety as well as safety or property before granting a waiver from the human error hazard analysis requirements of 14 code written — 14 code revelations.
  4. Develop and implement seizures and guidance for confirming commercial space operators are implementing the mitigations identified in a safety related waiver of regulations and work with the operators to determine the effectiveness of those that correspond to hazard with catastrophic outcomes.
  5. Develop and issue guidance for experimental permit applicants that include the information in the advisory circular 14- encourage commercial space vehicle manufacturers to begin the consultation process with the office of commercial space transportation during the vehicle design phase.
  6. Develop and implement a program for space transportation inspectors aligning them with individual operators applying for an experimental permit or launch license to ensure that they have adequate time to become familiar with the technical, operational, and training management controls that they will inspect.
  7. Develop management to work with technical staff to develop clearer policies, practices and procedures that allow direct communications between staff applicants. 2, providing clearer applicants on permits, waivers, and licenses. Three, better define the line between the information needed for public safety and the information pertaining more broadly to ensuring mission success.
  8. In collaboration with the commercial spaceflight industry, continue work to implement a database on the lessons learned on mishap investigations and encourage space industry members to voluntarily submit lessons learned.

Recommendations to the Commercial Spaceflight Federation

  1. Advise commercial space operators to work with local emergency response partners to revise emergency response procedures for planning to ensure that helicopter and other resources are appropriately deployed during flights.
  2. The last recommendation to them, work with the Federal Aviation Administration to develop an issue human factor guidance for operators to use throughout the design and operation of a vehicle. The guidance should address but not be limited to the human factor issues identified during the SpaceShipTwo accident investigation.