Filipinas.Clark Air Base · the black dot that climbed to 50,000 feet (1949)

Around noon on 8 September 1949 (04:00 GMT), a flight of three F-51 Mustang fighters of the 67th Fighter Squadron was flying at about 6,000 feet, some ten miles (16 kilometres) south-west of Clark Air Base on the Philippine island of Luzon. It was led by the squadron commander, Major Louis J. Sebille. During a turn, his left wingman, Lieutenant R. J. Semrau, called on the radio: "Look up to the right." Sebille saw an object climbing towards the north at high speed, at an angle of about 30 degrees, leaving a condensation trail. He estimated it to be at about 15,000 feet and some 30 miles (nearly 50 kilometres) away, reversed his turn and spread the flight to follow it.

His signed statement is precise. In the minute or minute and a half it took him to come round to north, the object reached about 50,000 feet. It was dark, and at that distance nothing more than a black dot could be made out. At that height it "made a sharp level-out not at all like an airplane leveling off after the climb", leaving a clear "elbow" in the trail. "My first impression was to start after it but obviously its speed was so great it was impossible." The trail was a thin line that had not dissipated at all from the south. From the separation it was gaining, he estimated it was travelling at "well over 800 miles per hour". Lieutenant R. R. Crew, the other wingman, told the same story: he saw the trail climb at 30 degrees, a slight course change in which the trail "curled in", and the level-off between 35,000 and 40,000 feet; he never saw what made it, and at 12:20, already on the ground, he could still see part of the trail. Semrau, who saw it first, had at first taken it for a skywriter. A fourth pilot, Lieutenant P. E. Welch, returning from a gunnery mission some 20 miles (32 kilometres) north of Clark, saw a very dense trail climbing north and levelling off at about 50,000 feet.

The fifth witness was on the ground. Lieutenant Harry C. Moore saw from the base service station the trail coming from the south, from Floridablanca, passing over the west side of Clark with a slight turn to the left and continuing north, above, he reckoned, 30,000 feet. And he added a decisive detail: that same morning he had flown from 08:00 to 11:45 at between 20,000 and 30,000 feet, and neither he nor the intercept aircraft he saw at 25,000–30,000 feet were leaving trails. The report also records the winds aloft, the weather —high cirrus and scattered cumulus— and the absence of test launches: the air attaché in Manila, the Navy, and the Philippine Army and Air Force all replied in the negative.

The duty intercept controller, Lieutenant Donald E. Williams, offered the simplest explanation: he had two F-51s at 30,000 feet that had taken off at 11:35 heading north to calibrate the radar, and he believed the trail was theirs and had formed late. On 4 October, the intelligence section of the Far East Air Forces command closed its supplementary report rejecting that idea: thirty minutes had passed between those aircraft taking off and the sighting, and only one trail was seen, not two. "This section is unable to discern what object or phenomena caused the above mentioned con-trail." Years later, when the case was transferred to a Blue Book card, the conclusion was the opposite: "Other (contrail)", with the investigating officer's opinion that the two F-51s had left it.

It is the corpus's first case in the Philippines and one of the best documented of 1949: five officers from the same squadron, four of them pilots in the air, with signed statements, wind and weather data, and an inquiry among the military services in the area. The main witness was no ordinary pilot: Louis Sebille died a year later in Korea, on 5 August 1950, diving his damaged aircraft into an enemy position, and was posthumously awarded the Medal of Honor, the Air Force's first of that war. His description —a black dot climbing to 50,000 feet and levelling off sharply— is that of someone used to judging aircraft in flight.

The most interesting thing in the file is the official disagreement. In 1949, the Pacific air command's intelligence studied the F-51 explanation, rejected it with two concrete arguments —the half-hour gap and the single trail— and admitted it did not know what it had been. Blue Book, in filing the case, adopted exactly the rejected explanation without new data. Lieutenant Moore's testimony, that he saw nobody leaving trails between 20,000 and 30,000 feet that morning, weighs against the delayed trail. It is an example of how a filing conclusion can be less careful than the first-hand analysis it summarises.

Even so, the case does not necessarily point to anything strange. Judging the height, distance and speed of a distant dot is very difficult, and an aircraft approaching high and straight can seem to climb as its trail forms in front of the observer. A jet or high-altitude aircraft not in the base's records —from another service, in transit or from another country— would produce a trail like this; the 800 to 1,000 miles per hour estimated are above the aircraft of the day, but they are guesses by eye. That is why the case spreads its weight between the mundane explanation and indeterminacy, with some for a friendly or foreign military aircraft and a remainder for the non-human because of the manoeuvre several pilots describe.