In addition to copyright, what about security classification.

I’m pretty sure I saw this document about 10 years ago in a professional capacity during the early project definition stage of a more recent airlifter. It was then still classified as “Secret” (embossed into the front cover and subject to sign in/out procedures). The 30 year declassification rule is not automatic and hence due process must be observed/recorded. I assume its been correctly declassified.