SpaceShip report: Anticipate possible human error

The National Transportation Safety Board (NTSB) report on the Nov. 31, 2014 crash of Space ShipTwo found that the failure to anticipate human error set the stage for the catastrophe.

The NTSB, in a public meeting at Washington, D.C. July 28, 2015, heard testimony by investigators and approved their report.

Co-pilot Michael Alsbury of Tehachapi died in the accident. Pilot Peter Siebold, also of Tehachapi, survived a 50,000-foot fall from the disintegrating vehicle.

The vehicle tore apart when the tail booms, or feathers, were activated prematurely.

Mojave-based Scaled Composites builds the conventionally powered mothership and the manned space rocket for Virgin Galactic.

The report concludes: “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.”

NTSB investigators found that “…Scaled assumed that pilots would correctly operate the feather system every time because they would be properly trained through simulator sessions and would follow the normal and emergency procedures for a given situation. However, this accident demonstrated that mistakes can occur even with a flight crewmember who had extensive flight test experience and had performed numerous preflight simulations during which the feather was unlocked at the proper speed of 1.4 mach.”

The NTSB recommended that the Federal Aviation Administration (FAA), in collaboration with the Commercial Spaceflight Federation, “develop and issue human factors guidance to use throughout the design and operation of a crewed vehicle.”

The NTSB also said the FAA and the Office of Commercial Space Transportation (AST) should develop clearer communication between its staff and applicants.

The report says that new safety procedures and data bases are necessary for the emerging world of space travel.

NTSB Chairman Christopher Hart, in opening remarks, said, “These two test pilots took on an uncommon challenge: testing technologies for manned commercial space flight, which is still in its infancy. Human space flight is subject to unique hazards, and test pilots work in an environment in which unknown hazards might emerge.”

“We cannot undo what happened, but it is our hope that through this investigation we will find ways to prevent such an accident from happening again, thereby helping to improve the safety of manned commercial space flight.”

In his closing remarks, Hart referenced the iconic scene in the film 2001: A Space Odyssey, in which a Pan Am passenger shuttle docks at a space station. Pan Am, he said, started a waiting list of people interested in taking a commercial space flight; the list grew to 93,000.

“Today, the vision of commercial space travel is close to fulfillment…but for such flights to proceed safely, commercial space transportation must continue to evolve and mature. The success of commercial space travel depends on the safety of commercial space travel, at the level of every operator and every crew.”

For more information,

see http://www.ntsb.gov or Space.com.