Mackinaw, IllinoisNovember 1961

On the night of November 20, 1961, two men plowing a field near Mackinaw, Illinois noticed a bright white light in the southwest sky. The men were jet engine mechanics attached to the 169th Tactical Fighter Squadron, stationed at an Air National Guard base in Peoria. Around 11:45 p.m., while working late to prepare the field for spring planting, they stopped their tractors to watch the object, which hung stationary in the sky for several minutes.

Without warning, the bright light suddenly broke apart into eight to a dozen smaller white lights. These lights clustered tightly together, dimming and brightening in no clear pattern. The cluster then moved smoothly across the sky from an angle of about 35 degrees elevation in the southwest to roughly 20 degrees elevation in the east, covering the visible arc in three to four minutes before fading into the distance. The witnesses reported a low, rumbling sound that resembled diesel engines, a pulsating jet, or thunder, audible even over their tractor engines. They also noted a small reddish trailing light that emitted occasional sparks.

A third witness, a farmer living about 3 or 4 miles away, reported seeing low-flying lights he took to be a large aircraft, though his account was vague on details. A fourth person, living 6 to 8 miles away, heard a strange noise he initially mistook for a diesel train.

An Air Force investigator visited the site in December 1961 and interviewed the primary witnesses at length. He explored the possibility that the object was a KC-97 tanker aircraft conducting a refueling operation called "Panda Bear," which ran between Indianapolis, Kansas City, Des Moines, and Springfield. The operation pattern matched the sighting location. The investigator theorized that the bright boom light used during refueling might have appeared as a single brilliant point until the tanker maneuvered on a straight line, at which point the separate landing lights of the tanker and the trailing jet aircraft became visible as a cluster. The sound could have resulted from the combination of the tanker's reciprocating engines and the jet's motors. However, the investigator noted that neither witness reported navigation lights (typically red and green), a detail that did not fit cleanly with the tanker hypothesis. He suggested the lights may have gone unnoticed against the overwhelming brightness of the refueling lights, or that the witnesses were too focused on the unusual light pattern to register ordinary navigation markers.

The case file concludes that the sighting likely resulted from a refueling operation in the Panda Bear sector, with a pattern of lights consistent with a tanker formation. No definitive explanation is stated, and the Air Force evaluation listed on the cover sheet is "unknown." The full case file of 14 pages is reproduced below as held by the National Archives.