Holy Toledo. My sister just sent me the contents of a NWA folder at the Minnesota Historical Society that cordwainer suggested.
The most important single document is a letter from Don Nyrop dated Dec 21 '62, discussing the CAB report that was released Dec 13. Nyrop says the report was "issued prior to the availability of all of the scientific data and tests necessary to establish a probable cause for the accident. The Board has been notified that there are at least 22 specific errors in the report it released on December 13. In our opinion, the Civil Aeronautics Board's findings are based on incomplete data, an unfinished analysis, and on conjecture."
Nyrop's letter was under a cover note that said it was clearly not intended for public consumption, but could be used as the basis for private responses.
I said elsewhere that it felt like the Lockheed engineers thought the CAB guys were a bunch of fools. Turns out NWA thought so too.
Holy Toledo.