Comment about three slots above:
"It [report] is ... later ... to negotiate (with Turkish Airlines, ATC and Boeing)... a report should be independent to be absolutely sure ... Negotiations should not be part of it...."
This report-writing method of first, a draft, and then await reply-comments, and THEN finally publish a report, saves the "investigating authority" from dumb mistakes. And that method provides more accurate final reports. Not all "investigating authorities" send-out their draft for err-correction/ comments, some won't even correct their dumb mistakes once published.