Type: Government Investigation
Source: United States Air Force - Project Blue Book
Following the July 17, 1957 encounter involving a United States Air Force RB-47H Stratojet, Project Blue Book conducted a detailed investigation into one of the most technically significant unidentified aerial phenomenon cases in its files. Unlike many reports received by the Air Force, the RB-47 incident involved simultaneous observations from multiple independent sources, including airborne electronic intelligence (ELINT) equipment, visual sightings by trained military personnel, and tracking by several ground-based radar stations.
Investigators reviewed mission reports, crew statements, radar information, electronic intelligence data, weather conditions, aircraft performance records, and communications between military installations involved in the event. Particular attention was given to the repeated detection of an unidentified radar emission by the RB-47's electronic countermeasures equipment while the aircraft simultaneously reported a visually observed luminous object.
Throughout the approximately ninety-minute encounter, the unidentified target reportedly maneuvered in ways that challenged conventional explanations. Crew members described the object changing direction, accelerating rapidly, disappearing from one location before reappearing elsewhere, and maintaining an apparent awareness of the aircraft's movements. Ground radar facilities independently confirmed unidentified targets during portions of the flight, providing additional corroboration beyond the aircraft itself.
Although investigators examined possible explanations including radar anomalies, atmospheric propagation, electronic interference, astronomical objects, and conventional aircraft, none successfully explained every aspect of the encounter. The combination of airborne ELINT detections, visual observations, and radar tracking distinguished the case from most other reports received during the Project Blue Book era.
Astronomer Dr. J. Allen Hynek later cited the RB-47 encounter as one of the strongest military UFO investigations conducted by Project Blue Book. The incident continues to be referenced by researchers because of the convergence of multiple independent sensor systems and experienced military witnesses. While Project Blue Book did not identify the object or determine its origin, the investigation remains one of the most significant official case files in the history of the program.