Northern Montana, March 1959March 1959

On the night of March 26, 1959, a B-52 bomber flying at 32,000 feet near the Montana-Canada border picked up an unidentified object on radar. The B-52 crew, led by Captain John W. Jackson, reported that something had been following them for about 15 minutes. They described seeing contrails (condensation trails) in their two o'clock position, trailing in a northerly direction. The object's contrails were thin and non-persistent, different from the thick, continuous trails left by the B-52 itself, even though the unknown object appeared to be flying at a higher altitude.

The B-52's tail gunner made radar contact with the object on his scope at 0241Z (2:41 a.m.). The Electronics Warfare Officer detected it moments later on the defensive radar system, determining that the object was transmitting radar signals on two frequencies: 9135 and 9130 megacycles. The object maintained a distance of 8,000 to 15,000 yards behind the B-52 for approximately one hour. At one point, the B-52 turned sharply to the right to begin a refueling operation, and the unknown object executed the same 73-degree turn to stay in formation behind the bomber. This maneuver convinced the B-52 crew that the object was deliberately following them.

A radar site at Great Falls, Montana, became aware of the situation and scrambled an F-89J fighter interceptor. First Lieutenant Austin E. Bond piloted the interceptor, with First Lieutenant Charles C. Abernathy as radar observer. At 0320Z, Bond reported visual contact with the object at approximately 20 miles distance. He saw red and green blinking running lights spaced roughly 30 to 40 feet apart, along with a steady white light in the middle that he assumed was a tail light. The arrangement of these lights suggested to Bond that the object had a delta or swept-wing shape, similar to an advanced jet fighter.

When the F-89J closed within about four miles, the object apparently detected the interceptor and changed course sharply from heading south to heading 350 degrees (roughly north-northwest). It began a rapid climb and increased speed. The pilot, now chasing at full throttle, managed to climb to his service ceiling of 43,000 feet while traveling at 0.84 Mach (roughly 500 miles per hour at that altitude). The object continued climbing away faster than the F-89J could follow. After about 19 minutes of pursuit, the interceptor crew lost sight of the object as it climbed beyond their capability to keep up. The chase was called off when the object was estimated to be about 24 miles away and still pulling away.

The investigation that followed revealed interesting details about what the crews observed. The B-52 tail gunner noted that when both the object and the F-89J appeared on his radar scope simultaneously, the unknown target produced a larger radar return (a brighter blip) than the fighter, suggesting a larger object or a particularly reflective surface. Meanwhile, the F-89J's own radar system produced no contact with the object, even when attempting to lock on. The ground radar station at Great Falls also failed to establish radar contact with the object itself, though they could track both the B-52 and the tanker aircraft nearby.

The Air Force's investigation involved questioning the crews and analyzing the technical evidence. The Electronics Warfare Officer reported that the object's radar was operating in a sweeping pattern with approximately one-second frequency intervals, but never actually locked onto the B-52. The fact that two different radar frequencies were detected raised the possibility of sophisticated electronic countermeasures. The file notes that Canadian authorities and U.S. fighter bases in the region were contacted to determine whether any known aircraft were airborne in the area. All replied negatively. A weather check showed clear skies with 25-mile visibility and winds of 42 knots from 340 degrees magnetic. These conditions ruled out weather phenomena as an explanation.

The investigating officer, Captain Urban A. Flero Jr., concluded that the most likely explanation was "a high-performance fighter interceptor of unknown origin." This conclusion was based on the object's demonstrated speed, altitude capability, ability to maneuver, and the pattern of radar emissions. However, he noted the significant unknown: no radar paint (visual confirmation on radar) was obtained of the object by the ground radar or the interceptor's fire control radar, only by the B-52's tail warning radar. This absence of independent radar confirmation, combined with the object's evasive behavior once intercepted, left open questions about its true nature.

The file was reviewed at higher levels of the Air Force. Analysts at Air Defense Command raised several theories. One suggestion was that the object might have been equipped with radar-absorbent paint, which could explain why ground radar and the interceptor radar failed to detect it while the B-52's defensive radar obtained good returns. Another theory proposed the object could have been a Canadian CF-100 or a U.S. U-2 reconnaissance aircraft, though officials noted these would have reflected well on standard radars unless their power output was well below normal. The Air Technical Intelligence Center (ATIC) ultimately stated that the object "appeared to have attributes of a normal aircraft, both in speed and maneuverability," and that there was "no information which would indicate any other type of airborne vehicle such as a balloon." However, ATIC also noted that no satisfactory explanation could be offered from a radar equipment standpoint, given the mixed results of radar observations.

The case was officially marked "unknown" by the Air Force. The full case file, comprising 20 pages as held by the National Archives, is reproduced below.