Improper co-pilot command
The NTSB says SpaceShipTwo’s co-pilot gave an improper command that led to the braking system deploying early. SpaceShipTwo’s fuel tanks and engine have been recovered largely intact and the hybrid motor fueled by nitrous oxide and a plastic-based compound was found five miles from where large tail sections first hit the ground. The condition and location of the wreckage suggest that an engine explosion didn’t cause the crash.