Part 15
Immediately after the Washington crisis, the Technical Development and Evaluation Center of the Civil Aeronautics Authority was assigned the problem of finding out exactly what had produced the radar returns. Investigation showed that the phantoms were not a new or unusual phenomenon. They had appeared on the Washington radars on many nights before the first “invasion,” appeared twice during the week between the two, and many times after the second. Abnormal returns are commonplace during the hot summer months when temperature inversions and inequalities in the moisture of the air are most frequent. On the nights of July 19 and 26 the Weather Bureau at Washington recorded small temperature inversions and an abnormal distribution of moisture in the atmosphere, conditions that regularly produce radar angels.
The experts also carried out a series of experiments in the Washington area on several nights in August when conditions of temperature and humidity closely resembled those on the “invasion” nights. During these experiments unidentified targets appeared in profusion on the radar screens. The first observation period began on the evening of August 13, 1952. At about 9 P.M. E.D.S.T., suddenly “a group of seven strong stationary targets became visible in an area about fifteen miles north-northeast of the radar antenna. During the next two or three antenna revolutions, the area on the scope between Washington and Baltimore became heavily sprinkled with stationary targets in a belt about six miles wide. A group of additional targets became visible in an area approximately ten to fifteen miles south of the radar antenna. This was evidence of the beginning of a temperature inversion.”[VIII-6] Two temperature inversions were involved, one just above the earth’s surface, and one at about 8000 feet. The investigators concluded that the unidentified targets observed on Washington MEW (Microwave Early Warning) and other radar in the summer of 1952 were to be attributed to secondary reflections of the radar beam, caused primarily by temperature inversions[VIII-5].
Saucer enthusiasts protested (and still insist) that the inversions were not large enough to produce radar anomalies, revealing how superficial was their acquaintance with radar. Although pronounced temperature inversions are responsible for the superior and inferior mirages resulting from the bending of light rays, large inversions are not required to produce the mirages resulting from the refractive bending of radio waves. At radar frequencies, refraction is influenced by both temperature differences and the distribution of water vapor in the atmosphere. A pronounced drop in moisture content at higher altitudes can easily cause radar rays to bend earthward and pick up ground targets, even though temperature conditions in the lower atmosphere are entirely normal.
In December 1952, _True_ magazine published a sensational article that attacked the Air Force findings, insisted that the radar echoes had been caused by strange machines and, in effect, accused the official investigators of releasing an explanation they knew to be at variance with the facts shown by radar[VIII-8].
Dr. Vernon G. Plank, now at the Aerophysics Laboratory of the Air Force Cambridge Research Center, was at that time Radar Meteorologist at Walpole, Massachusetts. A specialist in the science of radar, Dr. Plank had made a detailed study of the refractive conditions prevailing over Washington for July 20 and 21, 1952. In a letter (which was never published) to the editor of _True_, he pointed out that the saucer theory of the Washington radar returns had no basis in fact. The material given in the letter merits quotation:
“The regular Washington radiosonde observations, when converted into refractive index terms, reveal that a very marked superrefractive condition (a condition favorable to earthward bending of radar rays) prevailed in the lower atmosphere during this period. The cause of this superrefractive condition was primarily the rapid decrease of water vapor with altitude.
“Although this superrefractive layer was not quite intense enough to cause the radar rays to be bent completely back to earth, the rays would be very markedly bent downward from their normal position. From past experience with other situations of this type it is to be expected that certain regions in this layer might be considerably more superrefractive than others, or that particular terrain features, such as rivers or small bodies of water, might create local, transitory conditions favorable to extreme superrefraction or even reflection. Another factor to consider is that whereas such local anomalies are usually due to moisture, localized temperature effects may also create or help create such intense superrefractive regions. Therefore, it would not be at all surprising that such local anomalies, when superimposed on the generally superrefractive layer already existing over Washington, could create a situation conducive to radar echoes of the type observed.
“Under such conditions the general ground clutter referred to in the Keyhoe article would not be present and the radarscope would only show echoes whenever and ‘wherever’ (qualified below) a favorable superrefractive region occurred. As the radar ray has to travel from the radar set to the particular region of refraction and thence onward to the ground, the scope echoes created by such disturbances would occur at an indicated range of roughly twice the disturbance range.
“Even slow air movements within a localized disturbance (one sufficiently intense to bend the ray into the ground) would be translated into enormous movements of the echo over the scope face. Both lateral and radial movements could be expected and disappearance of echo between sweeps would not be surprising.
“Of course, the optical effects noted in conjunction with the radar echoes would depend upon temperature effects. However, the lack of a temperature inversion in the type of data referred to by Mr. Keyhoe does not preclude the possibility that extremely sharp and localized inversions existed over the area, perhaps in close association or in conjunction with the regions causing the radar echo. The Weather Bureau data cited are not sufficiently accurate nor do the instruments used in obtaining the data have a sufficiently rapid response to measure such small inversions. Also, such data are usually obtained at only two definite periods during each day.
“As the distance between Andrews AFB and the Washington National Airport is only some few miles, the refractive effects of a given disturbance might appear to be quite similar, and the position of the resulting ground echo on the two sets might coincide to a fair degree of approximation. However, as information about the degree of accuracy maintained in plotting echo position is not available to me, I cannot comment with any degree of intelligence. It does seem though, that with the observed echo speeds and radical direction changes, as well as the echo appearance and disappearance phenomena, that accurate scope coordination between the separate fields would be extremely difficult.”[VIII-9]
_“Simultaneous” Radar-Visual Reports_
On the night of July 29, three days after the second Washington crisis, the radar installation of the Air Defense Command post near Port Huron, Michigan, had been tracking three F-94s as they made practice runs on a B-25 bomber. At 9:40 P.M. C.S.T., ground control picked up an unidentified target moving from north to south at a speed of about 625 miles an hour. The operators notified the pilot of one of the F-94s and vectored him in for an attempted intercept. The plane’s radar did not show the reported target, but when the plane had climbed to a height of 21,000 feet, both the pilot and his radar man saw a brilliant multicolored light, many times larger than a star, close to the northern horizon. At the same time the plane’s radar picked up an echo in the north; it disappeared after thirty seconds, although the light was still visible dead ahead. As the pilot began the chase, the light changed color from bluish white to reddish and slowly diminished in size as though it were moving away. The pilot pursued the light for about half an hour without gaining on it, and eventually had to return to base. The ground radar, meanwhile, had been trying to keep track of events in the sky. When the chase began, the target appearing on ground radar had first made a 180-degree turn and reversed direction from south to north; it had then moved erratically, doubling its speed instantaneously, and then slowing down. It once seemed to reach a speed of about 1400 miles an hour, then slowed to about 300 mph, and disappeared from the scope shortly after the plane had returned to base[VIII-2].
To many persons this incident seemed a simultaneous visual and radar sighting of a single unknown object but the Air Force soon demolished this theory. A study of the facts revealed that the movement of the radar target and that of the mysterious light had not coincided. The radar target had traveled from north to south, had then reversed direction, had slowed down, speeded up, and moved erratically. The light, however, had remained steadily in the north, diminishing in size and brilliance but not vanishing. It behaved, in fact, like the image of a star or a planet seen through turbulent atmosphere (see _Chapter_ IV).
For several nights before the sighting, many residents in this part of Michigan had noticed a similar light that appeared in the northern sky each evening at about the same time and place, displaying various changing colors. The investigators were able to identify the shining unknown as the star Capella. The position of the lights coincided with that of the star for that time, date, and latitude. Capella was at lower culmination--that is, at the lowest point of its swing around the pole star, just skirting the horizon where its spectacular blue, yellow, and red twinkling is familiar to astronomers of the region. The pilot’s description, and the fact that he could get no closer to it even after a thirty-minute chase, confirmed this identification. Neither the brief blip that appeared on the plane’s radar nor the erratic returns picked up by ground radar had any relation to the star; they were merely phantom returns caused by weather conditions[VIII-2].
Like this Michigan sighting, many UFO problems are difficult to solve because they result from more than one cause. The observations seem at first glance to refer to a single phenomenon, although actually two or more unrelated phenomena are involved. On August 1, 1952, two days after the Michigan incident, such a puzzle arose with an impressive radar-visual-photographic sighting near Bellefontaine, Ohio[VIII-2]. At 10:45 A.M. C.D.S.T., the radar operator at the Air Defense Command post picked up an unidentified target north of Dayton, moving southwest at a speed of about 525 miles an hour. Two jets from Wright-Patterson Air Force Base were scrambled for an intercept and were vectored in by ground control. Since the ground radar was not equipped with height-finding devices, however, the operator could not direct the pilots to a specific altitude; he could only tell them whether they were nearer to or farther from the target.
When the jets had reached 30,000 feet, ground radar informed them that they were almost on target, which was still moving southwest at the same speed. A few seconds later, the returns from the jets and the UFO blended on the radarscope and the operator advised the pilots that they would have to continue the search visually. At this moment, unfortunately, the ground radar suddenly failed. Soon after communication between ground and air had ended, the lead pilot observed a silver-colored sphere several thousand feet above him. Both jets went after it but although they climbed to their maximum altitude, 40,000 feet, neither could get close enough to identify the object, which was still some 30,000 feet above them. One pilot, however, managed to expose several feet of film with his gun camera. At the same moment the warning light on his gunsight radar blinked on to indicate it detected a solid object. At this point the jets broke off the intercept and started back to Wright-Patterson Field.
Both pilots then realized that, although they had been chasing an unknown for some ten minutes, they were still northwest of the base in almost the same area where they had started the intercept. This surprising fact seemed to indicate that the unknown had slowed down from its original speed of 525 miles an hour, to hover in the sky nearly motionless.
In flying saucer circles, this series of events was regarded as an iron-clad case of a physically material UFO observed simultaneously by radar, the human eye, and the camera.
After sifting the evidence, ATIC investigators eventually found the more prosaic though complicated solution to the puzzle:
1) The object picked up on ground radar had actually been a jet plane, flying out of Cleveland. It had not been identified immediately because the Bellefontaine station had not received its flight plan. At 10:45 that morning the jet had been north of Dayton, flying at low altitude on a southwest heading, at a speed of around 525 miles an hour--the exact time, position, and speed of the radar unknown.
2) The pilots of the interceptors never saw this jet. What they saw, what their gun radar detected, and what their gun camera photographed was a twenty-foot radiosonde balloon that had been released from Wright-Patterson Air Force Base that morning shortly before the sighting. Ground radar, on the other hand, never picked up the balloon.
3) The chief reason for the confusion was that ground radar did not have a height-finding device. When the operator notified the pilots that his scope showed a blending of the returns produced by the pursuit jets and by the unknown, neither he nor the pilots had any way to tell whether the unknown was directly above or directly below the pursuing jets. At 30,000 feet the pilots were too high to see the Cleveland jet far below them. But they did see the balloon above them and naturally assumed that it was the object they were supposed to be chasing.
4) Since the ground radar stopped functioning at this point, the operator could no longer track the course of the unknown or of the interceptors. If the radar had been working, he would have seen that the target continued on to the southwest while the interceptors were searching in a different area to the north.
5) The photographs confirmed this reconstruction of a complicated series of events. The pictures obtained by the gun camera displayed a round, indistinct blur. Analysis showed that the size of the object was that of a twenty-foot sphere--a balloon--photographed from a distance of 30,000 feet.
_“Ghosts” and “Angels” on Radar_
Every experienced radar man has observed blips on his scope that he cannot account for[VIII-4], but he recognizes many characteristics of these “ghosts” or “angels.” They often come from an apparently clear and normal sky. They are usually concentrated in the lower atmosphere, are weak in character, and last only a short time. Although they may occur at any time of the year, they appear most often on summer nights in calm weather[VIII-10]. Summer atmospheric conditions, in which the air is relatively quiet but varies in temperature and moisture content, have an adverse effect on radio and radar transmission and produce many of these ghost returns.
The uneven distribution of temperature and humidity in the atmosphere is only one of the many possible causes of the radar angels often labeled as saucers[VIII-11, VIII-12]. These ghosts may be produced by peculiar atmospheric conditions, back and forward scatter of radio waves[VIII-13], smoke, wind-carried debris, moisture-laden clouds, ice crystals in clouds or air, lightning, meteors, the Aurora Borealis, birds, insects, bats, electronic reflections from the moon, flares on the sun, or by “chaff” or “window” (foil dropped from airplanes). A radar operator once picked up a group of phantom echoes that seemed to form the letters “GI” which, according to the scope, apparently stretched over a distance of about eighty miles. He tracked them for two hours, but gave up trying to interpret the message when he learned that it was produced by chaff dropped from an Air Force plane during an experiment.
An extremely unusual pattern of “angels” (see Plate IVc) appeared on the radarscope at Schilling Air Force Base at Salina, Kansas, on September 10, 1956, and was attributed to forward scatter from atmospheric eddies to ground targets and back[VIII-13].
Many radar angels are caused by insects and birds. Their detection on sensitive, high-resolution, Q-, K-, and X-band radars has been verified both observationally and theoretically. Since a radar set surveys a very large volume of the atmosphere and maps it on a relatively small dial, a surprisingly small concentration of insects can cause appreciable clutter on the scope. On sets such as the 0.86-cm TPQ-6 (Cloud Base and Top Indicator), a single insect of detectable size in a volume of 100,000 cubic feet of air is enough to fill the scope with return[VIII-4]. Since the guilty insect would be invisible both to ground observers and to the crew of pursuing jets, a flying-saucer report inspired by the radar echoes would remain forever an “Unknown.”
Birds can cause substantial echoes on many radars. Large birds at a distance of ten miles can give signals equivalent to those from a medium-sized aircraft at a distance of fifty miles; in fact, even the fading and fluctuation resemble those of aircraft echoes. On radar, a sea gull may cause a return equivalent to that of a quart of water flying around. The radar cross section of the blip may be several times larger than the geometric cross section of the bird, so that a single adult sea gull at a distance of twenty nautical miles gives a very large radar return. As few as eight birds per square mile can completely fill a PPI (Planned Position Indicator) scope with return[VIII-14]. If conditions were exactly right, the birds might be visible to an observer and the source of the angel would thus be explained. But if no one happened to see the birds, the “mysterious” returns could serve as a basis for still another report of invisible flying saucers.
Birds have also been responsible for some of the “ring” angels that have been interpreted as fleets of invisible spaceships. In September 1953 several radar sites in England picked up unidentified objects apparently encircling the city of London. They performed peculiar maneuvers including, according to one saucer publication, the formation of the letters Z and U of the English alphabet. How the correct orientation of this invisible sky writing was determined has never been explained. If the letters are turned top to bottom, back to front, or rotated 90 or 180 degrees, they take on new meanings. Scholars might well argue about whether the first giant symbol should be interpreted as a Roman Z, a Roman N, a Greek Ζ, or a Russian И; and whether the second symbol should be read as a Roman U, a Greek Ω, the mathematical symbol ⊂ standing for “is contained in,” or a Roman C lying on its side.
On the scope, ring angels produce outwardly expanding rings and arcs that sometimes move on and off the screen at incredible speeds. Such echoes have been a fairly common phenomenon in England since 1940 and 1941[VIII-15], and experimental research has shown that many of those occurring at dawn or at dusk are caused by flocks of starlings. At dawn thousands of starlings leave the roost in waves at intervals of about half a minute. The birds in each wave are often closely packed in a tight circle or semicircle as the wave ascends. All are flying outward, dispersing in all directions, so that the ring diffuses rapidly on the radar screen and disappears, but is followed almost at once by a new ring. At dusk the birds may return separately to the roost during the course of an hour. Sometimes, however, they assemble first in a field some distance from the roost; they finally take off at the same time as a group and head for the roost in a single giant wave, causing a tremendously impressive but quickly vanishing angel on the radarscope.
Ring echoes observed at Texarkana, Arkansas, have been traced to the movements of red-winged blackbirds. Thousands of birds flying out from a common roosting ground a few minutes before sunrise show up on the PPI scope as an expanding ring that grows broader and more diffuse with time until the composite echo breaks into individual ones and fades at a distance of twelve to thirty-five miles[VIII-16].
Other types of ring angels have been observed on radarscopes, but the causes are not yet fully understood[VIII-17, VIII-18].
Recognizing the true character of these radar angels and spurious reflections has tremendous importance for the security of the United States. Our Early Warning System, designed to notify Air Defense of imminent attacks by intercontinental ballistic missiles, has already had troubles with such radar ghosts. On October 5, 1960, a signal from Thule, Greenland, to the North American Air Defense Command flashed the warning, “Massive ICBM attack is underway.” The Canadian officer in charge had only seventeen minutes in which to decide whether to order several hundred bombers of the Strategic Air Command to retaliate against the USSR or to push the button that would cause our long-range missiles with atomic warheads to come roaring out of their underground sites. He immediately asked Washington: Where was Khrushchev? Khrushchev was in New York at the United Nations: the officer did not push the button that would have set the world at war.
Later, he learned that radar beams reflected from the moon had produced the terrifying angels. This incident is only one of the reasons why the Air Force continues to be interested in radar UFOs. Failure to identify them correctly could threaten the effectiveness of our patrol system.
_The Rapid City Sighting_
One of the most complex incidents in saucer history occurred early in August 1953 near Rapid City, South Dakota. Like the sightings the previous year at Bellefontaine, Ohio, and Port Huron, Michigan, the presence of a UFO seemed to be confirmed by several types of evidence. Trained civilian and military personnel on the ground and in the air observed an unknown visually and by radar. The blips on the ground radarscope were photographed and a plane’s gun camera took a picture. If a similar incident were to occur today, Air Force investigators would probably find the answer without difficulty. In 1953, however, they were less experienced and finally classified the case as “one of the best” Unknowns.
It is clearly impossible to solve the mystery with absolute certainty after nearly ten years, because vital information is lacking. The original records are no longer on file. Few details are available except those in Ruppelt’s sketchy summary[VIII-3, p. 303 ff.], and some of these are inaccurate: the town of Black Hawk, for example, is not west, but northwest, of Rapid City. Although many questions of fact must therefore remain unanswered--exact times, directions, sequence of events--we offer here a highly probable explanation.
The first report came at 8:05 P.M. M.S.T. when a spotter for the Ground Observer Corps in the town of Black Hawk telephoned the Air Defense Command post near Rapid City, approximately ten miles southeast of Black Hawk, to report an extremely bright light hovering low on the horizon to the northeast. The radar operators at Ellsworth Air Force Base had been working with a jet patrol flying west of the base. After receiving the phone call, they shifted the scope to scan the northeast quadrant of the sky and picked up an unidentified target moving slowly at about 16,000 feet. Although the controller wondered at first whether the target might have been due to weather, he decided after a few minutes that it was well defined, solid, and bright.