NEW YORK (TheStreet) -- In a meeting on Tuesday, the U.S. National Transportation Safety Board unveiled its findings that last year's crash of Virgin Galactic's SpaceShipTwo was largely tied to a number of human factors, including inadequate pilot training.

The NTSB said the accident occurred when SpaceShipTwo's co-pilot unlocked the "feather," the craft's brake system that is designed to create drag and reduce speed, too early. The craft was designed with the intention that pilots leave the feather locked until SpaceShipTwo reached Mach 1.4, or about 920 miles an hour.

But SpaceShipTwo's co-pilot, Michael Alsbury, moved to unlock the feather when the craft had reached about 0.8 Mach during the test flight, according to the NTSB. When the feather was unlocked, it extended un-commanded and caused the structural failure of SpaceShipTwo, which broke apart over the Mojave Desert just 13 seconds into its rocket-powered flight.

The pilot, Peter Siebold, was ejected and seriously injured, while Alsbury was killed in the crash.

It was the first powered test of SpaceShipTwo in nine months. Dr. Catherine Wilson of the NTSB said the board's investigation found that no safeguards to prevent this from happening had been put in place. She said there was also no warning, caution or limitation in the pilot operating handbook that specified that risk.

Wilson added that the only documented discussions about it occurred three years before the Oct. 31 accident and the pilots were not informed of this hazard.

NTSB Chairman Christopher Hart said it is his hope that through this investigation the board will find ways to prevent such an accident from happening again.

Richard Branson's Virgin Galactic ultimately hopes to begin taking paying customers to the edge of the atmosphere.