Libya.Tripoli · fighters chase something at sea that only radar saw

On the night of October 17 to 18, 1956, the 633d Aircraft Control and Warning Squadron, which ran the ground radar at Wheelus, a U.S. air base next to Tripoli, followed on its screen two objects moving slowly over the sea. That radar watched the sky over the area and guided the fighters: anything that reflected its waves, an aircraft or a flock of birds, showed up on the screen as a dot of light, a "blip", at its bearing and range. The military report speaks of two "unidentified slow flying objects" tracked "within a three (3) hour period".

The first appeared at 2217Z on the 17th (Z is Greenwich time). It flew at about 9,000 feet on a heading of 210°, toward the south-south-west, until at 2303Z it turned to 170°, almost due south; the radar lost it for a moment just before the turn and for good at 2303Z. The report gives its positions on a military grid; read on the GEOREF reference system, the first point lies over the sea about 60 nautical miles north-north-east of Wheelus (33° 47' N, 13° 50' E) and the turning point about 15 miles to the north-east, off the coast. That is 46 miles in 46 minutes, about 60 knots (about 110 km/h), along a line of 204° that matches the report's 210° and supports the reading (own calculation). The second object appeared at 2317Z about 62 miles north-east of the base (33° 39' N, 14° 07' E on the same reading; own calculation), at 5,400 feet, and when it disappeared it was at about 3,800.

To identify them, the ground radar diverted F-86D fighters of the 431st Fighter Interceptor Squadron toward them. Each fighter carried its own radar, part of its E-4 weapons system, and the chase followed a radio script: the pilot called "Judy" when he was tracking the object on his own radar and running the approach himself; "Splash" marked the end of the attack, the point at which the system would have fired its rockets; and "Tally-ho" meant he could see it. Two fighters went after the first object. Both found it on their radar and carried through to "Splash" without seeing it at any time.

Two more, call signs F/Blue 1 and F/Blue 2, went after the second; the report does not say whether they were the same aircraft. Both were at 5,000 feet. F/Blue 1 found the object on his radar at 2357Z, two miles away; he called "Judy" at one mile at 2358Z and reached "Splash" at 2359Z, 35 miles from the ground radar. F/Blue 2 found it at 2359Z, four miles away, when he was 32 miles from the ground radar; he called "Judy" at 32 as well and reached "Splash" at 34. Neither called "Tally-ho". The report says nothing about the next 47 minutes, up to 0046Z. In that time the object went from 35 to 30 miles from the ground radar and moved about 9 miles west, at about 12 knots, without coming closer to the coast (own calculation from the bearings in the report).

At 0046Z the two fighters tried again, now at 3,800 feet, the altitude the ground radar gave the object when it disappeared. F/Blue 1 found it at two miles, called "Judy" at one and reached "Splash" at 0047Z; F/Blue 2 found it at two miles and reached "Splash" at 0046Z, both about 30 miles from the ground radar. According to the report, that was the last contact of any radar with the object. Neither pilot saw it, and both were released to land because they were running out of fuel.

F/Blue 1 stated that just before each "Splash" his fighter was just above the clouds, just below them or between them, "but never in a cloud", and that the blip on his screen was "very bright". Neither object tried to evade the fighters, and there was no other air traffic in the area. On the weather, the pilots gave "no ceiling" (no cloud layer covered more than half the sky), ten nautical miles of visibility and a ten-knot wind from the north, and the report notes that in that season migratory birds cross the Mediterranean southwards.

On October 29 the 7272d Air Base Wing Combat Operations Center wrote a secret report, IR-1-56, with the radar squadron and the fighter squadron as sources. Its first paragraph concludes: "No satisfactory explanation of these occurrances could be determined. This incident is considered important because of the positive and repeated radar indications of an object in the air." The officers who prepared it saw migratory birds as "one possible explanation" but "unlikely": one of the objects was at 9,000 feet, the fighters' repeated approaches would have diverted or broken up a flock, and they thought it improbable that a fighter's radar would hold a flock all the way to "Splash". Nor did they think a temperature inversion likely, a layer of warmer air over colder air that can bend radar waves and produce misleading blips, "because of speed of movement and weather conditions".

More than eight years later, on February 11, 1965, Vincent D. Bryant, an electronics engineer at the Air Force Foreign Technology Division (FTD) at Wright-Patterson Air Force Base, wrote about the case to Sergeant Moody: "The fact that the visibility was 10 miles and the pilot saw nothing (visually) when he had closed to less than a mile is an indication that there was no material target; it seems most likely that some sudden change in the atmospheric characteristics - not necessarily temperature inversion as such - may have caused the return." On birds he wrote: "Birds can give radar returns, but we concur that birds would be unlikely to maintain a given course, ( or remain in the vicinity of aircraft) for so long a period of time". It is the only paper in the file that proposes an atmospheric cause.

The file kept by Project Blue Book, the Air Force project that studied UFOs, opens with the case card. Its summary reads "No visual sighting of objects. Bright return on both ground and air radar" and, further down, "All returns indicate solid object & some object rather than interference due to WX or anomalous prop": nobody saw the objects, both radars showed a bright blip, and everything pointed to a solid object rather than interference caused by the weather or by waves bending abnormally. Under conclusions, the "Unknown" box carries a smudged mark, and above the "Other" line, crossed by an ink stroke, "WEATHER RETURNS" is typed in a different typeface. That annotation is undated and does not say what it rests on.

The strength of the case is that two kinds of radar confirmed each other. The ground radar led the fighters to where it saw the objects, and each fighter's radar found them there, followed them in to one or two miles and held them to the end of each approach. That happened at least six times (those described in the surviving extract of the report), on two different objects, between 2217Z and 0047Z, two and a half hours (own calculation from the report's times). That is why the report speaks of "positive and repeated" radar indications, and whoever wrote the card summary stated that the blips indicated a solid object. The weakness is that nobody saw anything, and that what survives is an extract that leaves out several items of the five-page original report, without the radar records.

The conclusion left on the card appears to rest on Bryant's note, whose argument is that nobody saw anything: with ten miles of visibility, a pilot at less than a mile should have seen a material object. The approaches were flown at night, though not in darkness: the almost full Moon (97% illuminated) stood high over the area, about 58° above the horizon at 2217Z, 45° at 2358Z and 36° at 0046Z, with the Sun more than 50° below the horizon (own calculation). And the pilot himself said he was passing close to clouds; "no ceiling" does not rule them out, and the report does not say how much of the sky they covered. With a high Moon Bryant's argument carries more weight than on a dark night, but not seeing an unlit object or a flock at one mile, at night and close to clouds, still does not prove there was nothing there.

The 1956 objection to a temperature inversion rests on a fact in the record, the speed of movement: about 60 knots for the first object (own calculation), with a 10-knot wind according to the pilots. But the file has no upper-air wind data, and Bryant's proposal, which requires not an inversion but a sudden change in the characteristics of the atmosphere, does not require the blip to move with the wind either: that fact weakens it without refuting it.

The other explanation the report itself raised, migratory birds, fits some of the figures. The first object moved at about 60 knots toward the south-south-west (own calculation from the GEOREF reading of its two positions). The second, if the ground radar was at Wheelus, which the report does not specify, went from about 62 miles north-east of the base at 2317Z to about 35 at 2359Z, some 38 knots in the same general direction (own calculation). Up to then both were approaching the coast from the north, with a northerly wind and in the season when, according to the report, birds cross the Mediterranean southwards; afterwards the second drifted west at about 12 knots without coming any closer (own calculation). Against it weigh the arguments, already quoted, of the officers in 1956 and of Bryant in 1965. The file proves neither of the two ordinary explanations.

Another Blue Book file from the same base, from September 1957 (1957-09-7228589), records a yellowish-orange sphere that a helicopter pilot watched from the ground for three or four minutes; there was no radar, and Blue Book closed it as "Was Aircraft". In October 1956 there were no visual witnesses, but a ground radar and the fighters' radars on at least six approaches, and the doubt it leaves is the one radar almost always leaves when nobody sees anything: whether something was in the air or the air itself made the blip.