Mantauk, N.Y. to Benson, Pa., September 1957September 1957

On September 20, 1957, two radar stations detected high-speed targets moving westward across the northeastern United States. The first radar unit, located at Montauk, New York, picked up a target at 1506Z (3:06 p.m.) traveling at an estimated 5,400 knots. The second unit, near Benton, Pennsylvania, detected what was thought to be the same target at 1918Z (7:18 p.m.) moving westward at about 960 knots. Other radar stations along the reported track were alerted but failed to make contact with the supposed targets. F-102 fighter aircraft were scrambled from bases in Michigan and Wisconsin to intercept, but found nothing unusual. The tracks eventually faded in the vicinity of Benton, Pennsylvania, not near SAC Headquarters in Nebraska as had been initially reported.

A NORAD investigation team studied the incident over the following days. On September 25, the team observed a series of blips on the Montauk radar scope that were identical to those from the original sighting. When the radar frequency was changed, the blips disappeared. When the original frequency was restored, the blips reappeared. Meanwhile, investigators discovered that two Strategic Air Command aircraft had dropped streams of radar chaff (thin metal strips used to confuse radar) near the Benton station on the day of the incident. The team concluded that the radar characteristics of the targets were completely abnormal and likely caused by equipment malfunction.

The full NORAD analysis ruled out several possible explanations. The speeds and courses of the two track segments did not correlate well, suggesting they came from different causes. A ballistic missile could not have accounted for the observed track length and duration. A cruise missile was theoretically possible only for one segment of the track. Meteors were extremely unlikely, as the radar frequencies were too high to detect them effectively. Aurora borealis effects did not match the observed scope presentations. Weather conditions at the time showed no unusual atmospheric layers that would produce false radar targets.

The team's final conclusion was that the Montauk track was most probably caused by a circuit malfunction or interference from a non-rotating radar unit, while the Benton tracks were most probably caused by equipment malfunction at that station. No evidence suggested the targets were hostile aircraft or missiles. The investigation found that much of the information obtained was contradictory, making it difficult to reach definitive conclusions. The investigators recommended further technical study to better understand the phenomenon, should it occur again.

The full case file of 52 pages is reproduced below as held by the National Archives.