According to the cover page,

Issued by
The Office of the Chief of Naval Operations
Aviation Training Division
U.S. Navy, 1960
Revised January 1965

Which means the US Navy owns the copyright, not an individual.

The new cover on the book attributes

Naval Air Systems Command
US Navy

Looks like anyone is allowed to republish it, being a US Govt. doc.
I notice both ASA and Jeppesen have reprints available.