Project Blue Book Case #2521. On March 25, 1953, another unidentified object was observed over San Antonio, Texas — making this the third Blue Book unknown from America's most concentrated military aviation city, following cases in May and September 1952. San Antonio's four Air Force bases — Lackland, Kelly, Randolph, and Brooks — created an unmatched density of military aviation expertise.
By March 1953, the Robertson Panel's recommendations to debunk UFO reports were beginning to influence Blue Book operations. The CIA-sponsored panel had concluded in January 1953 that UFOs posed no direct threat to national security but warned that public interest in them could clog intelligence channels. Despite this institutional pressure toward conventional explanations, the San Antonio case could not be resolved.
The persistence of unknowns over the San Antonio complex was particularly troubling because it suggested that whatever was being observed was either a recurring natural phenomenon that defied identification or a genuine unknown that repeatedly appeared over sensitive military airspace. Neither possibility was comfortable for Air Force intelligence.
The March 1953 object exhibited the same resistance to identification that had characterized the earlier San Antonio cases. All flight operations across the four-base complex were checked, weather data was reviewed, and no conventional explanation emerged.
The case was classified "Unknown" — extending San Antonio's status as one of the most prolific sources of unresolved Blue Book cases.