Mildenhall, England, October 1957October 1957

On October 19, 1957, tower operators at RAF Mildenhall in England watched a circular disc-shaped object move slowly across the sky. The object was described as roughly the size of a dime held at arm's length, and its color shifted between yellow and orange. Two radar stations also picked up targets matching the sighting. The entire incident lasted about 29 minutes, after which the object disappeared beneath cloud cover.

The sighting began around 1720 (5:20 p.m.) local time when two airmen, A/2C Harold R. Pringle and A/2C Allen B. Warsewich, spotted the object in the southwest. It appeared to hover at first, roughly five degrees above the horizon. As it moved westward over the next several minutes, it descended to about four degrees above the horizon. At 1755 (5:55 p.m.), the station's weather observer was notified. He confirmed he could not identify the object but was certain it was not a star or other celestial body. By 1809 (6:09 p.m.), clouds had obscured it from the tower's view.

During the sighting, observers noticed an unusual disturbance in radio receivers. Nearby RAF stations at Lakenheath and Waterbeach reported having no aircraft in the area. Starting around 1930 (7:30 p.m.), radar stations at Lakenheath, Mildenhall, and Schulthorp picked up multiple targets that moved slowly or remained stationary. The radar blips were described as unusually circular and fuzzy, with an appearance distinct from normal aircraft returns. One RAF Meteor aircraft was guided to the area but reported negative visual contact.

The investigating officer, 1st Lt. David A. Zilliter, noted that extensive surveys found no weather balloons, aircraft, flares, or other ordinary explanations in the area at the time. In his conclusion, Zilliter stated the reports appeared conclusive and that the sighting definitely involved an unidentified object. No photographs or physical evidence were recovered. The full case file is reproduced below as held by the National Archives across 7 pages.