on 29 July 1952, immediately after the big UFO flap at Washington National Airport, Ruppelt wrote that "his [Samford's] people had fouled up in not fully investigating the sightings." Astronomer and Blue Book consultant J. Allen Hynek thought that Ruppelt did his best, only to see his efforts stymied. Hynek wrote "In my contacts with [Ruppelt] I found him to be honest and seriously puzzled about the whole phenomenon". After Blue Book Ruppelt requested reassignment from Blue Book in late 1953 shortly after the Robertson Panel issued its conclusions (based partly on the panel's official report, Ruppelt's Blue Book staff was reduced from more than ten personnel to three, including Ruppelt). He retired from the Air Force not long afterwards, then worked in the aerospace industry. In 1956, he worked as a research engineer for Northrop Aircraft Company, according to publisher information in the online version of his 1956 book The Report on Unidentified Flying Objects. Hynek suggested that Ruppelt's "book should be required reading for anyone seriously interested in the history of this subject". In the book, Ruppelt detailed his time with Projects Grudge and Blue Book, and offered his assessments of some UFO cases. In 1956, Donald Keyhoe asked Ruppelt to join to serve as an adviser to the newly created National Investigations Committee On Aerial Phenomena (NICAP) . Ruppelt had recently suffered a heart attack, and declined Keyhoe's offer. Ruppelt's book indicates that he held some dim views of Keyhoe and his early writings; Ruppelt stated that while Keyhoe generally had his facts straight, his interpretation of those facts was another question entirely. He thought Keyhoe often sensationalized the material and accused Keyhoe of "mind reading" what he and other officers were thinking. In what would turn out to be a matter of months before his death, Ruppelt came out with an expanded (20-chapter) edition of his book - as published by Doubleday & Co. In new chapters notably conservative in tone, and frequently attributed by reviewers to author disillusionment or disenchantment, Ruppelt declared UFOs a "space age myth". Content of this nature was of a noticeably different tone to famous quotes from the original "Report" that had, for example, referred critically to a 1949 change of attitude in the Project whereby: "everything was being evaluated on the premise UFO's couldn't exist. No matter what you see or hear, don't believe it". Ruppelt had also been prompted