Evaluation of Air Defense Incident of 20 September 1957

This document is a comprehensive evaluation of an air defense incident that occurred on 20 September 1957. The incident involved the detection of high-speed radar tracks by the 773d ACWRON at Montauk Air Force Station, New York, and subsequently by the 648th ACWRON at Benton Air Force Station, Pennsylvania. The tracks were initially reported as unidentified objects moving at speeds ranging from 2,000 to 5,400 knots at an estimated altitude of 50,000 feet. The report details the operational procedures followed by the NORAD system, including the scrambling of F-102 interceptors from Kinross AFB and Truax AFB, which failed to make contact with any targets. The investigation, conducted by a NORAD team, analyzed the radar data, weather conditions, and potential missile or meteor activity. The team concluded that the radar returns were not characteristic of normal aircraft. Specifically, the tracks exhibited a 1.0 blip/scan ratio, which is highly unusual for conventional aircraft. The investigation found that the Montauk station had experienced equipment malfunctions, and the Benton station had been conducting chaff-dropping exercises with SAC aircraft. The report suggests that the observed phenomena were likely the result of radar equipment malfunctions, interference, or 'angel effects'—a form of random noise produced by electronic components. The report explicitly states that no hostile aircraft, missiles, or vehicles were in the area at the time of the sightings. The conclusions are presented as statements of relative probability rather than definitive facts, noting that the information was often contradictory. The document includes detailed technical appendices, including weather forecasts and refractive index computations, to support the conclusion that atmospheric conditions were not the primary cause. The final recommendations call for further technical investigation to isolate the phenomenon should it reoccur. The document is marked as unclassified and includes various internal memoranda and correspondence regarding the handling of the report and the briefing of Congress.