1953 Ellsworth UFO sighting ,Important Radar-Visual UFO

On August 5 and August 6, 1953 the US Military investigated a UFO incident in Bismarck, North Dakota. What has become known as the Ellsworth Case is one of the most significant radar-visual cases in the annals of UFO sightings.
A lady spotter at Black Hawk, about 10 miles west of Ellsworth, had reported an extremely bright light low on the horizon , radar had been scanning an area to the west, tracking a jet fighter in some practice patrols , but when they got the report they moved the sector scan to the northeast quadrant ,there was a target exactly where the lady repored the light to be ,The warrant officer who was the duty controller that night studied the target for several minutes ,it was at 16.000 feet.
The warrant officer called to the F-84 pilot he had on combat air patrol west of the base and told him to get ready for an intercept , By this time the pilot had it spotted. He made the turn, and when he closed to within about 3 miles of the target, it began to move away, the UFO picked up speed fast and started to climb, heading north, the F-84 was on its tail.
The chase continued on north ,when the UFO and the F-84 got about 120 miles to the north, the pilot checked his fuel; he had to come back.
Both the UFO and the F-84 had gone off the scope, but in a few minutes the jet was back on, then 10 or 15 miles behind it was the UFO target also coming back.
A second plane was launched and the pilot saw it right away and closed in , he switched on his radar-ranging gunsight, In a few seconds the red light on his sight blinked on - something real and solid was in front of him ,he asked the controller if he could break off the intercept .
When the UFO went off the scope it was headed toward Fargo, North Dakota.
Bellow is a report by J. Allen Hynek

In 1953, the year of the Robertson report, there occurred one of the most puzzling cases that I have studied.

At approximately the same time, unidentified blips showed up on the radarscope at Ellsworth Air Force Base, which is near Black Hawk. An airborne F-84 fighter was vectored into the area and reported seeing the UFO's. The pilot radioed that one of the objects appeared to be over Piedmont S. Dak., and was moving twice as fast as his jet fighter. It was "brighter than the brightest star" he had ever seen. When the pilot gave chase, the light "just disappeared." Five civilians on the ground, who had watched the jet chase the light, confirmed the pilot's report.

As the object sped off to the north, Ellsworth Air Force Base notified the spotter's control center in Bismarck, 220 miles to the north, where a sergeant then went out on the roof and saw a UFO. The Air Force had no planes in Bismarck that could be sent after the UFO, which finally disappeared later that night.

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Actual Project Blue Book Document
Ellsworth UFO Document 1
Ellsworth UFO Document 2
Ellsworth UFO Document 3