VSS Enterprise crash

Investigation

The National Transportation Safety Board (NTSB) investigated the accident. A Go Team was dispatched to the accident site on October 31, 2014. The team, consisting of around fifteen personnel, arrived at the Mojave Air and Space Port on November 1. They began their investigation that day.

At a news conference on November 2, NTSB acting chairman Christopher Hart said the lock–unlock lever for the vehicle's feathering mechanism was moved to the unlocked position at slightly above Mach 1. SpaceShipTwo's feathering mechanism then began moving even though that motion had not been commanded. The on-site investigation was scheduled to take four to seven days. It was reported on November 12 that the on-site investigation had been completed and that parts of the wreckage had been placed in secure storage should they be needed for further investigation. It was expected to take about a year for the final report to be released.

During a hearing in Washington D.C. on July 28, 2015, and a press release on the same day, the NTSB cited inadequate design safeguards, poor pilot training, lack of rigorous federal oversight and a potentially anxious co-pilot without recent flight experience as important factors in the 2014 crash. They determined that the co-pilot, who died in the accident, prematurely unlocked a movable tail section some ten seconds after SpaceShipTwo fired its rocket engine and was breaking the sound barrier, resulting in the craft breaking apart. The Board also found that the Scaled Composites unit of Northrop Grumman, which designed and flew the prototype space tourism vehicle, did not properly prepare for potential human slip-ups by providing a fail-safe system that could have guarded against such premature deployment. "A single-point human failure has to be anticipated," board member Robert Sumwalt said. Instead, Scaled Composites "put all their eggs in the basket of the pilots doing it correctly."

The report's details of the final moments of the flight reveal that the feather system was unlocked as SS2 accelerated under rocket power through Mach 0.92 at 10.07:28, 9 seconds after release from the WhiteKnightTwo (WK2) carrier aircraft and 14 seconds before the vehicle would have reached Mach 1.4, the minimum speed at which the tail was designed to be unlocked. Telemetry, in-cockpit video and audio data confirmed that co-pilot Michael Alsbury announced "unlocking" as Mach 0.92 was passed and vehicle breakup occurred within the next 4 seconds. The feathering device, conceived by Scaled Composites designer Burt Rutan, is deployed after reaching maximum altitude, increasing drag and slowing descent as a carefree and stable reentry method for recovery of SpaceShipOne. The system operates by rotating the vehicle's twin tail booms upward about the trailing edge of the wing by around 65 degrees; following reentry, the actuators rotate the booms down into the flush position for approach and landing. Aerodynamic forces when accelerating through the transonic moments of the flight, above Mach 0.85 and below Mach 1.34, push upwards on the tail; releasing the locks before the vehicle passes these speeds means that a pair of actuators were the only things keeping the tail in place against these powerful forces, which had unintentionally been sufficient on earlier test flights.

Investigators said the developer of the spacecraft failed to include systems to protect against human error, believing that highly trained test pilots were simply incapable of making a wrong move, and that co-pilot Michael Alsbury may have been influenced by time pressure, along with strong vibration and acceleration forces he had not experienced since his last powered test flight in April 2013. The combination "could have increased the co-pilot's stress." The board found that during years of development and flight tests, engineers at Scaled Composites assumed that any pilot mistakes would occur only in reaction to systems failures, not as the cause of such failures. The Flight Test Data Card for this mission, giving information on the test vehicle and the step-by-step mission plan, called for the feathering system to be unlocked at Mach 1.4, but did not indicate that unlocking early could be a danger. The NTSB investigators also found just one email, from 2010, and one presentation slide, from 2011, that even mentioned the risks of unlocking before completing the transonic stage of the acceleration. The NTSB members also criticized the FAA, which approved the experimental test flights, for failing to pay enough attention to human factors or to provide necessary guidance to the nascent commercial space flight industry on the topic. They also cited pressure from some FAA managers to quickly approve experimental flight permits, sometimes without fully understanding technical issues or the details of the spacecraft.

In its submission to the NTSB, Virgin Galactic says the second SS2, nearing completion, had been modified with an automatic mechanical inhibit device to prevent locking or unlocking of the feather during safety-critical phases. An explicit warning about the dangers of premature unlocking has also been added to the checklist and operating handbook, and a formalized crew resource management (CRM) approach, already used by Virgin for its WK2 operations, is being adopted for SS2. This will include call-outs and a challenge/response protocol. While the report cites CRM issues as a likely contributing cause, Virgin says there is no plan to modify the cockpit display system.

NTSB chairman Christopher Hart said that, as the Board had learned "with a high degree of certainty the events that resulted in the breakup", he hoped the investigation would prevent such an accident from happening again. "Many of the safety issues that we will hear about today arose not from the novelty of a space launch test flight, but from human factors that were already known elsewhere in transportation." Hart added "for commercial spaceflight to successfully mature, we must meticulously seek out and mitigate known hazards, as a prerequisite to identifying and mitigating new hazards." Virgin Galactic is proceeding with its plans for space flight and is building another craft; company officials said that their commitment to commercial spacecraft had not wavered despite the crash and they expected the company to resume test flights later in 2015, though that date subsequently slipped. On 19 February 2016, Enterprise'''s successor, VSS Unity, was unveiled by Scaled Composites and Virgin Galactic.

Virgin Galactic CEO George T. Whitesides, in a news conference following the incident, said that "Space is hard and today was a tough day." Virgin founder Richard Branson said after the crash: "We do understand the risks involved and we are not going to push on blindly—to do so would be an insult to all those affected by this tragedy. We are going to learn from what went wrong, discover how we can improve safety and performance and then move forwards together," and "Space is hard, but worth it."

Michael Moses, Head of Operations for Virgin Galactic, admitted to tensions between Richard Branson's upbeat projections and the persistent hurdles that challenged the company's technical experts. "There's a difference between the marketing and the engineering sides of the company", Mr. Moses said on November 10, 2014.

The International Association for the Advancement of Space Safety (IAASS) heavily criticized Virgin Galactic within hours of the accident. Tommaso Sgobba, Executive Director of the IAASS, claimed that Virgin Galactic had refused to let IAASS scientists review its procedures and snubbed industry gatherings. He stated: "They operated in secrecy, which is difficult to understand. They don't use modern techniques in putting safety into the design. They use outdated methods like testing and then seeing what happens. There has been no independent oversight. There is no peer review. I have been saying for some years now this was an accident waiting to happen." Sgobba, the former head of flight safety for the European Space Agency, said on November 6, 2014, that industry best practice called for operators to build in "two-failure tolerance", or sufficient safeguards to survive two separate, unrelated failures—two human errors, two mechanical errors or one of each. "What we see in the incident is what we call 'zero-failure tolerance'," Mr Sgobba said. "So you make the mistake—you have a catastrophe. The design would not be acceptable in other safety-critical industries, such as aircraft manufacture."

Other members of the IAASS were quick to provide public comment on the rocket propulsion system before the completion of the NTSB investigation. Rocket-powered dragster builder and IAASS spokesperson Carolynne Campbell-Knight said that Virgin Galactic "should stop, give up. Go away and do something they might be good at like selling mobile phones. They should stay out of the space business.". Geoff Daly wrote to the U.S. Chemical Safety Board in July 2013 describing his safety concerns over SpaceShipTwo. Daly's concerns centered around the use of nitrous oxide in the hybrid propulsion system.

Despite these public criticisms, the final NTSB report found that the propulsion system did not in fact contribute to the breakup of the vehicle.

Several key employees had resigned from Virgin Galactic within the year leading up to the crash, including the Vice-President of Safety, Jon Turnipseed, and Vice-President of Propulsion, Thomas Markusic.

In an editorial in Time magazine on October 31, 2014, Jeffrey Kluger concluded, "A fatal accident in the Mojave Desert is a lesson in the perils of space hubris. It's hard not to be angry, even disgusted, with Branson himself. He is, as today's tragedy shows, a man driven by too much hubris, too much hucksterism and too little knowledge of the head-crackingly complex business of engineering. For the 21st century billionaire, space travel is what buying a professional sports team was for the rich boys of an earlier era: the biggest, coolest, most impressive toy imaginable."

On November 13, 2014, the Wall Street Journal published an article discussing the history of safety and technical problems of the aircraft, citing unnamed engineers and a former government official involved with the project. According to the article, the official said that nagging vibrations were "very distressing to pilots because they simply couldn't read their instruments"; Virgin Galactic denies this claim. The engine did not have enough power to lift six passengers into space, so Virgin Galactic switched to a new nylon-based fuel, the Journal reported. At a test of the new fuel earlier in 2013, "an explosion all but obliterated the test stand", according to the Journal's sources.

In 2021, both Alsbury (posthumously) and Siebold were honorarily awarded the FAA Commercial Astronaut Wings.

The incident was featured in the 2018 episode "Deadly Mission" of the Canadian TV series Mayday''.