The Ota Air Base Encounter: Júlio Miguel Guerra's Chipmunk Circled by a UFO

Base Aérea N.º 2 sits at Ota, about 50 km north of Lisbon. On the morning of Tuesday 2 November 1982, Lieutenant Júlio Miguel Guerra, a Portuguese Air Force flight instructor, took a DHC-1 Chipmunk trainer up alone. Around 10:50 he was flying north over the country west of the Serra de Montejunto, near Vila Verde dos Francos, toward Torres Vedras. His altitude was about 5,000 feet.

Below him, something bright was moving from north to south. At first he took it for another aircraft, or a reflection on his canopy. Then it "climbed straight up to my altitude of 5,000 feet in under 10 seconds."

Guerra described it as "round with two halves shaped like two tight-fitting skullcaps." The upper half was "brilliant and reflecting the sun." The lower half "seemed to be somewhere between red and brown with a hole or dark spot in the center." A band around the middle "looked like it had some kind of a grid, and possibly a few lights." Measured against the Chipmunk's fuselage, it was about 8 to 10 feet across.

Then it began to circle him. It "flew at a fantastic speed in a large elliptical orbit to the left," he said, "always from left to right, repeating this route over and over." Guerra turned hard to keep it in sight, his neck twisted fully to the side. He radioed Ota tower. The tower confirmed there was no other traffic in the area.

A second Chipmunk flew out with two more Air Force pilots, Carlos Garcês and António Gomes. For about 10 minutes they watched the object repeat its elliptical course, passing between the two planes on each return.

Then it came straight at Guerra. It "stopped there, like a helicopter landing but much, much faster, breaking all the rules of aerodynamics." It held within a few metres of his plane. He remembered thinking, "well, that's it for you!" Then it shot off "in a flash toward the Serra de Sintra and the sea."

All three pilots filed separate written reports. The next day Guerra drew the object and attached the sketch to his report. No photographs exist, and no radar data is given.

The Air Force Chief of Staff, General José Lemos Ferreira, released the files to a civilian scientific group, CNIFO, directed by historian Joaquim Fernandes. Lemos Ferreira knew the subject firsthand. In 1957, as a captain, he had led a formation of F-84s that reported a UFO. CNIFO's team reportedly included physicists, meteorologists, psychologists and engineers. It estimated the object's horizontal speed at about 2,500 km/h.

A weather balloon was suggested over the radio while the encounter was still under way. The pilots rejected it. Guerra pointed out that no balloon could reach his altitude in under 10 seconds or fly a repeating, powered ellipse. The investigation did not adopt the idea. No detailed sceptical analysis has been published, and the Air Force left the sighting logged as unidentified.

Guerra went on to fly for Portugália Airlines as a Line Captain, with about 17,000 flight hours. In 2010 he told the story in his own chapter of Leslie Kean's book UFOs: Generals, Pilots and Government Officials Go on the Record, with his drawing. RTP2 had already given the case an episode, "Ota," in its 2008 series Encontros Imediatos. It remains unexplained.