A single mistake by the co-pilot led to the fatal disintegration of a Virgin Galactic space plane during a test flight in October, the National Transportation Safety Board concluded Tuesday, and the board strongly criticized the company that designed and manufactured the plane for not building safeguards into the controls and procedures.

“Many of the safety issues that we will hear about today arose not from the novelty of a space launch test flight,” the board’s chairman, Christopher A. Hart, said during a hearing in Washington, “but from human factors that were already known elsewhere in transportation.”

The safety board was also critical of the Federal Aviation Administration for not following up on issues that could result in mistakes by pilots.

The craft, called SpaceShipTwo, is designed to be carried aloft under a larger aircraft, then dropped before its rocket ignites and propels it upward. Near the top of its ascent, two tail booms rotate upward into a “feathered” position. That is meant to create drag and stability, allowing the plane to descend gently back into the atmosphere, much like a badminton shuttlecock.