Willow Run 6-3:
Questions: does NTSB have some review process by which it goes to (for example) ALPA with the results of its investigation, before preparing its report, and ask whether such a representative of pilots would add any other data or tests? Does NTSB vet an outline of its proposed analytic framework for identifying probable cause? Does it circulate a draft report to anyone outside the agency for comment before making and declaring it final?
The UPS pilot union, Independent Pilots Association, has their own accident investigation team involved with the NTSB investigation. The investigation process in very thorough, taking into account information from many sources.