The Air Force investigation into Monday’s B-1 bomber crash will produce two reports ... one the public gets and the second that remains classified.
The safety investigation is designed to allow investigators the ability to ensure confidentiality to aircrew members and maintenance workers. This way, they get a more-candid look at what could have caused the crash; helping the Air Force avoid future crashes.
The safety investigation board works quickly; pouring over sequestered maintenance records and taking testimony from people involved in the crash; as well as searching for clues at the crash site.
Part of the safety investigation report, basically just the facts, is given to another investigation board and can be incorporated in the publicly-released report. However, the section that includes the confidential testimony will never be released.
What the public ends up with is the basic cause of the crash, including information about what could have lead up to it.
The Air Force usually releases the public report within 60 to 90 days of the crash.