The National Transportation Safety Board later concluded that the breakup was caused by Alsbury's premature unlocking of the air brake device used for atmospheric re-entry.

The NTSB said other important factors in the accident were inadequate design safeguards, poor pilot training and lack of rigorous oversight by the Federal Aviation Administration (FAA).

About eleven seconds later, the space plane violently broke apart,[7] substantially giving the appearance of an explosion, and creating a 35-mile-long (55-kilometer) debris field.

[11] A preliminary investigation and cockpit video subsequently indicated that the feathering system, the ship's air-braking descent device, deployed too early.

[19][20][21] Investigators were initially puzzled about how Siebold managed to get out of the rocket plane and parachute to the ground from an altitude of roughly 50,000 feet (15,000 meters), where the atmosphere is virtually devoid of oxygen.

[31] 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.

[32] During a hearing in Washington D.C. on July 28, 2015,[33][34] and a press release on the same day,[35] 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.

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.

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.

[37] 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,[38] 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.

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.

[36] 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."

Virgin Galactic CEO George T. Whitesides, in a news conference following the incident, said that "Space is hard and today was a tough day.

"[41] 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.

[48] 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.

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.

"[10] 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.