LUKE AFB, ARIZONAMarch 1953

On March 3, 1953, Captain Roderick D. Thompson was leading a flight of three F-84 fighter jets on a simulated combat mission near Luke Air Force Base in Arizona when he and his fellow pilots spotted something unusual in the sky. At about 1:25 p.m., at an altitude of 25,000 feet, Thompson observed a condensation pattern (a trail of moisture left behind by a moving object) that looked nothing like anything he had ever seen before.

When Thompson first spotted the pattern, it appeared to be roughly 300 to 500 feet in diameter. What made it so peculiar was that the object itself was invisible, but the trail it left behind had an odd shape. The pattern began with a smooth, knife-like leading edge and developed into a crescent shape. It was very thin from front to back and had an irregular, wispy trailing edge. Unlike normal aircraft contrails (which spread across the sky as the aircraft flies), this contrail stayed tightly formed with its source.

Thompson turned to chase the object, climbing at full power. As he maneuvered, the object made a sharp dip toward the northwest and began climbing at about 20 degrees. At this point, the contrail suddenly became much heavier and more pronounced, stretching back approximately 1,000 feet before splitting into a double trail. Thompson estimated the object was traveling at about 400 miles per hour. He chased it for about 30 to 50 miles, firing roughly 30 feet of gun camera film from his F-84, before breaking off the pursuit and continuing to his base. Two other pilots in the flight also observed the contrail, though neither chased it.

Air Force photographers and analysts examined Thompson's gun camera film in detail. They concluded that the white streak in the photographs was indeed a vapor trail produced by a rapidly moving object of unknown type. The film showed characteristics consistent with a twin-engine or twin-exhaust propulsion unit, as the trail appeared to fork or split at points. The analysts also noted what appeared to be a second, broader vapor component, possibly from lifting surfaces such as wings, that dissipated quickly. The visible evidence suggested the object was accelerating in response to being chased, since the exhaust trail was more pronounced toward the end of the film than at the start.

Despite extensive analysis and investigation, no one was able to identify the object. Local aircraft were checked, and no conventional military or commercial aircraft were found to be in the area at the time. The Air Force consulted with experts on guided missiles, who concluded that the type of contrail observed could not have been produced by a missile at that altitude. Some analysts suggested it might have been two separate aircraft flying at high altitude, though the evidence was inconclusive. The object remained unidentified throughout the investigation.

The case file notes mention that an Air Force fact sheet claimed the service had no films or photographs of unidentified flying objects, but this Luke AFB case directly contradicted that claim, since it was an instance where a military pilot's gun camera film captured an unidentified object's vapor trail and remained classified as unknown after thorough analysis.

The full case file, consisting of 42 pages as held by the National Archives, is reproduced below.