Project Blue Book Case #1708. On July 28, 1952, an unidentified object was observed over McChord Air Force Base — the third Blue Book unknown from this Tacoma-area installation (following Cases #1298 and #1332 from June 1952). McChord's production of three unknowns made it one of the most prolific repeat-sighting bases in the entire Blue Book database.
The July 28 sighting came during the absolute peak of the great wave — the same day as the McGuire AFB case in New Jersey, one day after the second Washington, D.C., radar events. McChord's air defense mission, protecting Seattle and the Boeing complex, made each unknown a security concern. The case was classified "Unknown."
