United States.RB-47 ECM Encounter

On July 17, 1957, a USAF RB-47H (electronic reconnaissance variant of the B-47 Stratojet) departed Forbes AFB, Kansas, on a combined navigation, gunnery and ELINT exercise over the southern United States. The aircraft carried a crew of six officers under the command of Major Lewis D. Chase. Three of them were electronic warfare operators (Ravens 1, 2 and 3) running the ELINT (Electronic Intelligence) receivers installed in the aircraft's countermeasures bay, designed to detect and catalog enemy radar emissions.

As the aircraft crossed the Gulf coast near Gulfport, Mississippi, the operator monitoring the S-band receiver (the band used by air-defense radars of the era) picked up a signal that moved relative to the aircraft in a way no fixed ground radar could explain. Shortly afterward, the cockpit crew sighted an intense bluish-white light holding relative position with the bomber. The object was tracked across four states — Mississippi, Louisiana, Texas and Oklahoma — over a path that, per McDonald's reanalysis, exceeded 600 miles (more than 1,100 km) and lasted roughly an hour and a half. Air Defense Command ground radar stations, including the Duncanville (Texas) site, confirmed returns correlated with the position reported by the crew.

The case's signature is the correlation between three physically independent channels: the onboard ELINT detection, the ADC ground radar, and the crew's visual observation appeared and disappeared roughly simultaneously at several moments during the encounter. The object exhibited abrupt changes of position and, in at least one episode described by the crew, a halt and reappearance that operators registered nearly in unison on their scopes. When the signal was lost, it was lost on all three systems; when it returned, all three recovered it. These features are what the Condon Committee's radar specialist, Gordon Thayer, considered impossible to reconcile with the explanation Project Blue Book offered at the time (that the case was due to commercial airliners), a characterization Thayer called 'literally ridiculous.'

Ten years after the encounter, in June 1967, Major Chase contacted Condon Committee investigator Roy Craig at a conference in Boulder, Colorado, which reopened the file. Atmospheric physicist James E. McDonald interviewed several crew members and reconstructed the case in detail; his work was presented at the 1969 AAAS symposium and in Flying Saucer Review (1970). The Condon Committee cataloged it as Case 5 and, after examining several hypotheses, classified it as unexplained.

It is probably the best declassified radar-ECM-visual triangulation of the Cold War. Its analytical value lies not in the drama of the sighting but in the architecture of the evidence: three physical systems operating on different principles (a passive onboard radiofrequency receiver, an active ADC ground radar, and the human eye) coincided in both detecting and losing the signal. That convergence is hard to attribute to a single source of error: an instrument fault does not simultaneously produce an S-band return, a ground-radar return, and a visible light moving together across 1,100 km.

Editorial honesty requires noting the file's limitations. McDonald himself lamented that the immediate official flight report was never located, so the reconstruction rests largely on interviews conducted a decade after the events, with the inevitable memory problems that entails. Skeptics such as Philip Klass argued that the reported timings and frequencies could be due to interference or confusion with signals from known ground radars, though Thayer and McDonald countered that this reading failed to account for the sustained tracking or the multichannel correlation. What survives that debate is that a committee funded by the Air Force itself — designed, many critics argue, to close the subject — could not explain the case and left it cataloged as unknown. That concession, made by an institution with no incentive to make it, is what keeps the RB-47 among the few cases with quasi-institutional backing for its anomalous character.