Chapter VIII
PHANTOMS ON RADAR
The evidence of radar, according to the saucer enthusiasts, provides final proof that alien spaceships indeed patrol our skies. Because radar is an electronic device, it allegedly cannot be fooled by mirages, reflections, or peculiar weather conditions. If radar records an echo from an unidentified object and, at about the same time, a human witness reports a puzzling light in the sky, the believers proclaim that the unprejudiced testimony of science has confirmed the presence of a solid flying saucer. Sometimes a radarscope reports unidentified objects at a time when observers on the ground and in search planes cannot see anything unusual in the sky. The believers then conclude not that radar evidence can be misinterpreted, but that the operators of the flying saucers may somehow be able to make both themselves and their ships invisible![VIII-1]
Radar as a Reporter
Any UFO investigator who presumes to evaluate electronic evidence should have much more than an amateur’s knowledge of the nature and behavior of radar. Correct interpretation of the signals requires training, experience, skill, and an expert’s acquaintance with the peculiarities of the set under varying conditions. But even the expert does not yet understand the causes of all the phenomena that can appear. He is limited by our still incomplete knowledge of dynamic meteorology—precise information about the composition of the atmosphere and how it interacts with microwaves. With proper instrumentation and first-rate operators, radar can correctly report the approximate direction, distance, altitude, and rate of motion of objects within its range. If the returns are misinterpreted, however, radar can seem to give false reports.
Radar is not a TV camera or a photographic lens. It does not, at least at present, produce a picture of the physical appearance, shape, size, or color of the thing it detects. The scope shows only tiny spots of light on the flat surface of a screen. A pointer something like a clock hand continually sweeps around the dial at a given speed. A complete rotation may take from two to fifteen seconds, depending on the type of the set. This sweep hand keeps pace with the rotation of the radar antenna as it scans the sky by sending out radio pulses. When they encounter a solid object, they bounce off and return to the set as echoes which show as “blips,” or spots of light, on the radarscope. The operator must interpret these spots and try to identify them as planes, helicopters, balloons, ships, mountains, clouds, birds, storms, hurricanes, or phantom echoes of various kinds. Safe commercial flying depends on the accuracy of these identifications, as does the security of the country in periods of international tension.
Radar only reports. It does not interpret. If the sweep hand on successive rotations shows a spot of light apparently moving from position A to position B, to C, to D, the operator generally concludes that the blips represent a single object that is moving at a certain speed in a certain direction (see Figure 13). If successive sweeps show a spot of light that remains at position A, he usually concludes that it represents a stationary object. If the blip moves a very great distance in the interval between two sweeps or seems to jump erratically from one position to another, an amateur might interpret it as a spacecraft flying at incredible velocity—a flying saucer. But an expert would probably conclude, especially under certain weather conditions, that the scope was picking up echoes from two or more separate objects, one reflecting briefly at position A, another at position B, and so on.
The Principle of Radar
Radar is an electronic assembly far too complex for detailed description here, but its basic principle is simple. It is merely an echo machine that reflects radio waves instead of sound waves. To illustrate by a rough analogy, let us imagine that a man is standing in the middle of an open field on a very dark night. He wants to find out something of the contours of the surrounding country but his only tools are a compass, a watch with luminous dial and hands, and a large megaphone. He raises the megaphone to his lips, points it directly north, and gives a sharp and piercing call: “Hi!” He now cups his hand to his ear and listens for an echo. Hearing no reply, he deduces that in the north there are no hills, tall buildings, or other obstructions that might have produced an echo.
Changing his position, he turns to the east and tries the experiment again. After an interval his call returns as a faint echo: “Hi!” The time elapsed between call and echo, according to his watch, is ten seconds. His call has taken five seconds to reach the object and five seconds more to return. Since he knows that sound travels at the rate of about 1000 feet a second, he deduces that an obstruction lies in the east, about 5000 feet away. Slowly changing position, he repeats his call at various points around the compass. Some echoes take longer to return than others, indicating more distant objects. Other echoes come back in a fraction of a second, showing an object very close. Thus he gradually constructs a mental map of the surrounding terrain.
Radar detects and locates objects in a similar way, by reflecting sharp pulses of radio waves. But spurious echoes, which sometimes deceive the operator, can also appear on the scope. These “anomalous” or abnormal returns may have one of several causes, including the nature of the radar mechanism itself. To help explain this, let us go back to our analogy of the man in the open field. Let us suppose that the man has mechanized his device. To ease the strain on his vocal cords, he has built a megaphone with a record-playing device. The megaphone rotates automatically and sends out a recorded “Hi!” once every twenty seconds, as regular as clockwork. To increase the sensitivity of his hearing, he wears ear trumpets that point in the same direction as the megaphone. This procedure is more effective than cupping his ears and eliminates some of the extraneous noise that might come in from the rear and the sides.
With this improved equipment the man now repeats his experiment. As before, he gets no signal from the north. When he turns to the east he gets an echo after ten seconds, just as he did during his first experiment. As he continues to turn slowly, like a minute hand on a clock dial, he mentally maps the positions of the echoes as distances along the hand from the center of the dial, and compares this new map with the crude one he constructed earlier. Basically the two agree.
But wait! From the southwest he hears a new echo that did not occur in his earlier experiment. It returns after two seconds and thus apparently comes from an obstruction 1000 feet away. Puzzled, the man decides to walk toward the object and check his observation. After he has covered half the distance he stops, sends out a call, and listens for the echo. The indicated distance to the echo-producing object is now 500 feet, just as he calculated. And so he goes on, checking at intervals. When he has covered 990 feet he knows that he should reach the obstruction at any moment and to avoid colliding with it in the darkness he proceeds with extreme caution—995, 996, 997, 998, 999 feet. He puts out his hand, expecting to touch a building or a stone wall, and warily takes the last step. But he finds no structure of any kind, merely level ground. And at the same moment he finds to his astonishment that he can no longer detect the echoes he had been following. What has happened? Has his equipment been malfunctioning? Or was the unknown structure perhaps a vehicle from outer space that waited until he was practically touching it and then rose silently in an enormous burst of speed and vanished?
The man checks and finds that his equipment is functioning perfectly, since he can still pick up echoes from the terrain he had mapped earlier. He then walks back ten feet and listens once more for an echo from the phantom structure. Again he gets a signal, apparently from an obstruction just ten feet ahead. Has the mysterious object suddenly returned? But how could it have done so without disturbing the atmosphere or making a noise? By this time our man is frightened as well as puzzled, but he boldly decides to make one more experiment. He walks again to the point where the obstruction should be. Signaling again to the southwest, he now gets a faint echo apparently from a distance of 10,000 feet. Tired as he is, he starts walking toward this new obstruction and eventually reaches his goal. He now finds the true source of the returns—a high hill that rises abruptly from the plain. The hill is 10,000 feet away from the position indicated by the original series of echoes, and 11,000 feet away from the place he stood when he first sent out the signals.
Finally the man figures out the explanation. When he made his first experiment, with primitive equipment, he had given one sharp shout and then waited for a long time for the signal to return; thus there was never any uncertainty about the source of the echo. The time that elapsed between shout and return had clearly indicated the distance of the echo-producing object. But the improved automatic equipment of the second experiment produced a train of signals going out continuously at regular intervals, twenty seconds apart. Therefore when the sound waves encountered a definite object, a train of echoes began coming back, twenty seconds apart. An object at a distance of 10,000 feet would return an echo in twenty seconds; another object at a distance of 11,000 feet would return an echo in twenty-two seconds. But an echo from this second object would reach the listener at exactly the same time as an echo from an object only 1000 feet away. He now understands why he seemed to detect a structure at a distance of 1000 feet which disappeared as he approached and then reappeared 10,000 feet farther away. In fact, the object that returned the misinterpreted echo could have been 20,000 or 30,000 or 40,000 feet farther away—any multiple of 10,000 feet. Large numbers of signals were returning every twenty seconds. The man had no way of deciding for certain whether a particular echo came from the most recent signal and therefore indicated a relatively close object, or whether it came from an earlier signal and therefore from a more distant object.
Broadening his experiment our man eventually learned other characteristics of these echoes. He found that on the average day he was rarely plagued by this uncertainty in identifying the returns. The second-round echoes were very weak, almost undetectable, and therefore caused no major problem. But on other days, under different weather conditions, sound tended to travel long distances without losing much in intensity. On such days the echoes were often confusing.
Weather and Radar Echoes
Radar is an echo machine that reflects radio waves instead of sound waves. Instead of traveling at the speed of sound, about 1000 feet a second, radio waves travel at the velocity of light, 186,000 miles a second. Successive pulses go out at very short intervals, perhaps one one-thousandth of a second apart, so that each pulse is followed by another just 186 miles behind it. If the operator gets a return from an object that is apparently at a distance of 25 miles, he must sometimes allow for the possibility that he is getting a secondary echo and that the actual distance may be different. The object that produces the echo may be at a distance of 25 plus 186 miles, or 25 plus twice 186 miles, or 25 plus any other whole-number multiple of 186 miles.
Under ordinary circumstances, the reflections from very distant targets rarely confuse the operator. The curvature of the earth tends to shield the radiation, and the distance factor alone reduces the intensity to a negligible value. But weather can cause peculiar returns. A layer of warm air above cooler air at the earth’s surface has much the same effect on radio waves that it has on light waves. A temperature inversion can produce radar “mirages”—commonly called “phantoms,” “ghosts,” or “angels.” Relatively small amounts of warm air, even mere warm bubbles in a layer of colder air, will suffice. When the scope records a series of blips, the operator ordinarily assumes that all are returns from a single object. If inversions of temperature or humidity exist in the atmosphere, however, the series of returns may represent several different ground objects rather than a single object in the sky. Since these inversion layers do not remain fixed but move, change, and shimmer, on one sweep the radar may reflect one ground object and on the next sweep some fifteen seconds later may reflect a totally different ground object five or six miles away from the first. An inexperienced operator might conclude, wrongly, that both echoes came from a single object that had traveled five miles in a fraction of a minute (see Figure 14). Similar mistakes in identity have caused many reports of radar flying saucers.
Such a radar incident occurred at one of our defense installations in Alaska early in the morning of January 22, 1952[VIII-2]. Shortly after midnight a bright target appeared on the radarscope, moving down from the northeast, fairly high, and apparently traveling at about 1500 miles an hour. Unidentified targets require particularly prompt investigation in this sensitive area so close to Siberia. Within minutes an F-94 jet was moving in from a fighter base 100 miles to the south; two other jets were scrambled at intervals and vectored in toward the unknown target by ground radar. When radar switched to short range, however, it always lost both the target and the pursuit plane, even though both were close to the radar site. The first jet could find nothing in the air, and no echoes appeared on its radar. The second jet saw nothing in the air, but its radar recorded a brief, weak echo to the right at about 28,000 feet. The echo faded immediately, returned briefly, and then disappeared as the jet closed in. The third jet, after cruising the area for ten minutes without detecting anything visually or on radar, suddenly got a strong radar return from an apparently stationary target just as it passed over the ground radar site. The pilot made three direct runs on the unknown. Each time he broke off the intercept when he got within 200 yards of the target position as shown on his radar, for fear of collision. At no time did he see anything at the supposed location of the target. (This experience is somewhat analogous to that of our man who used echoing sound waves to locate a solid structure only to find, on reaching the indicated spot, that the structure was not there.)
Captain Roy James, chief of the radar section of ATIC, examined all the data and the scanty weather reports then available for this Alaskan area, and concluded that the targets were ghost returns probably from the ground, caused by peculiar atmospheric conditions—the same conditions that had interfered with normal operation of the ground radar. Although ground structures are scarce in that part of Alaska, they do exist, and so do mountains. The analysis was undoubtedly correct, even though knowledge of the location and movement of the temperature inversion was too imprecise for the analyst to plot and locate the true target that produced the reflections[VIII-3, p. 167].
Some of the nation’s most brilliant physicists have carried out fundamental research into the behavior of microwaves under varying conditions. The technical nature of these investigations makes them difficult to describe in ordinary language, but they provide vital information for the expert.
One such study has specifically attacked the problem of radar images that perform rapid and erratic maneuvers at close range and seem to overtake, fly parallel with, or almost collide with the pursuing aircraft. Such returns may be caused by the “non-isotropic secondary scattering of energy” (that is, the radio waves are not reflected in a uniform manner) from an airplane to a ground object, or from ground object to plane. Under appropriate weather conditions the plane itself causes the puzzling echoes, so that the velocity and movement of the radar “saucer” depend directly on those of the plane. When the aircraft is the first of the two scatterers, the radar saucer always appears at the same bearing as the plane, and is always farther away from the detecting radar than is the plane. Thus the path of the phantom always lies outside the path of the aircraft, and when the jet performs a 360-degree turn, the phantom also turns, on an outside path. However, if the jet happens to fly directly over the ground object that is reflecting the energy, then the observing radar will see the images of the jet and the phantom flying on what seems to be a collision course.
Conversely, when the ground object is the first of the two scatterers, the saucer phantom always occurs at the same bearing as the ground object, and the distance to the phantom is always greater than to the ground object. If the aircraft crosses the radial line from radar to ground object, at a range exceeding the range to the object, then the echoes from plane and saucer almost merge at the point of crossing, in a “near collision.” But if the plane flies “this side” of the object, then the plane and saucer will never be closer together than the distance between plane and ground object at the point of crossing. A height-finding radar, trained on the pursuing plane, would show the phantom saucer apparently diving toward or climbing away from the plane, attacking and retreating at very high velocities[VIII-4].
The Kinross Case
Some such mechanism probably explains the radar returns reported in the Kinross case, which some saucer publications cite as a proved instance in which a flying saucer attacked a plane. On the night of November 23, 1953, an Air Force jet was scrambled from Kinross Air Force Base, Michigan, to intercept an unidentified plane observed on radar. The jet successfully accomplished its mission and identified the unknown as a Dakota, a Canadian C-47. On its return to the base, however, the Air Force jet crashed into Lake Michigan and, as often happens when a plane crashes into deep water and the exact place of the crash is not known, no wreckage was ever found. As the ground radar at Kinross had tracked the returning jet, the scope had picked up a phantom echo in the neighborhood of the jet; the two blips had seemed to merge just as both went off the scope.
Since the crash was not reported as a UFO incident and did not involve any question of unidentified flying objects, ATIC was not asked to investigate the problem. The office of the Deputy Inspector General for Safety carried out a thorough inquiry and concluded that the crash had been an aircraft accident, probably caused by the pilot’s suffering an attack of vertigo. As for the two blips shown by radar, the night had been a stormy one and atmospheric conditions had been conducive to abnormal returns. The phantom echo had almost certainly been a secondary reflection produced by the jet itself, and it thus merged with the return from the jet and vanished with it when the plane hit the water.
Solely on the basis of this radar phantom, some civilian saucer groups have tried to transform the Kinross crash into a UFO mystery with Air Force investigators as the villains, and have suggested that the ghost blip represented an alien spacecraft that happened to be cruising over Lake Michigan that night and attacked the jet for one of two reasons: 1) The saucer might have tried to avoid close contact with the jet by employing a “reversed G-field beam” (see Chapter IX); colliding with this beam as with a stone wall, the jet crashed. 2) The saucer might have used the G-field to scoop the plane out of the air and take it aboard the spacecraft; the captured pilot might have been needed to teach the English language to his alien captors.
The “Invasion” of Washington, D.C.
The most famous of the radar phantoms are those that “invaded” Washington, D.C., on the nights of July 19 and July 26, 1952, and terrified a large number of radar operators, pilots, and Air Force officials who in a more normal emotional climate would have recognized the “invisible” flying saucers for what they were—radar angels produced by weather conditions[VIII-2]. All during July the eastern seaboard had suffered an unprecedented drought and heat wave. Lack of cloud cover produced intensely hot days and rapid radiative cooling of the earth’s surface at night. This situation, combined with the prevailing light winds, was ideal for the formation of low-level temperature inversions during the hours of darkness[VIII-5].
The hundreds of flying saucers reported during the summer (Chapter VII) had produced a state of near-panic which entered its acute phase on July 19, at 11:40 P.M. E.D.S.T., when a group of seven unidentified targets appeared on the radarscope of the Air Route Traffic Control (ARTC) at the Washington National Airport[VIII-3, p. 209 ff.]. Similar targets that moved erratically, appearing and disappearing, were observed on the radars of the control tower and of nearby Andrews Air Force Base. If the blips were to be accepted at face value, then a host of aerial objects had invaded Washington and were cruising over the White House and the Capitol. Traffic control notified the pilots of commercial flights in the area to keep alert for unidentified aircraft. Some pilots reported unusual echoes on their plane radars, some reported only normal returns, and two pilots reported unexplained lights in the neighborhood indicated by radar. Nobody saw any strange aircraft. After several requests from ARTC (which unaccountably did not notify officials in the Air Force Intelligence that an “invasion” was taking place), a jet interceptor finally arrived about dawn to search the area but found nothing. Meanwhile the targets had vanished from the radarscopes.
Next day the report flashed all over the world that a fleet of flying saucers had invaded Washington, and public tension became almost tangible. Was the earth doomed? The terror reached its climax on July 26, just a week after the first incident, when at 10:30 P.M., E.D.S.T., the same radar operators who had observed the first “invasion” picked up another group of mysterious blips on their screens. The host of unknowns had apparently formed a ring around the city of Washington and the surrounding countryside. This time Air Force Intelligence officers were notified. They raced to the airport to see the radarscopes for themselves, and concluded that real saucers must be in the sky. All commercial air traffic was then diverted from Washington, reporters and photographers were barred from the radar room, and Air Force jets took to the air to defend the nation. But against what? The enemy, if there, was invisible. One pilot saw a bright light that vanished when he began to chase it; later, his radar showed a return that faded after a few seconds, but he could not find a visual target. In the hours between midnight and dawn, jet interceptors scoured the skies looking for mysterious objects that produced returns on ground radar but not on plane radar, and were invisible to the human eye. They found nothing.
One pilot who flew this mission, accompanied by a copilot who was also a radar officer, later described his experience:
“For a period of 1½ hours the B-25 was vectored at altitudes varying from 1,000 to 4,000 feet MSL to the objects observed on the [ground radar] screen. The airplane flew circles around stationary blips, flew through and along with their formations, paralleled their flight, and was observed in the radar screen to pass directly over, under, or through an angel. At all times the echo return of the aircraft caused a brighter return on the screen than the angel. The radar height finder was not operating during this mission, so exact altitudes of the blips could not be determined.
“No unidentified objects were observed by me or the crew during the flight. At 2300 E.D.S.T. all angels disappeared from the radar screen and screen detection returned to normal.”[VIII-6]
By dawn this fantastic war of the angels had ended and the post-mortems had begun. One radar expert who kept his head in spite of the hysteria was Captain Roy James of ATIC, who immediately recognized the targets as caused by weather. A civilian expert on radio propagation, when consulted, correctly identified the phantoms and explained how they were produced[VIII-7, VIII-7a]. General Samford, then in charge of the UFO investigation, concurred. But most newspapers and many government officials, influenced by the general excitement, ignored the conclusions of the experts. Saucer enthusiasts regarded the phenomena as a real invasion from space, and alleged that the Air Force was covering up the truth.
Weeks passed before the facts of the incidents could be separated from the fancies. Three ground radars had observed unusual targets on the nights of the “invasion.” Only once, however, did all three observe what was apparently the same target, and that for a few seconds only. The unusual radar echoes had no visual counterpart—nobody had seen or heard a spaceship. A few pilots had reported unidentified lights, but the Washington area at night displays thousands of lights, and even an unexplained light is far from being a spaceship. One pilot who took part in this phantom war reported that, again and again, ground radar had vectored him in toward a target that proved to be a steamboat making a moonlight trip on the Potomac!
Radar Experiments in Washington
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.
Since the ground spotter had a visual target and the traffic controller had a radar target, he telephoned to compare notes on positions; as they were talking, the spotter interrupted the conversation to say that the light was beginning to move southwest toward Rapid City. Checking the radarscope and finding a fast-moving target the controller sent two of his men running outside to look at the sky. After a few seconds they reported that they could see a large bluish-white light moving toward them from the northeast. It made “a wide sweep” around Rapid City and then returned to a stationary position in the northeast where it had first appeared. (Unfortunately the account does not state clearly whether the “wide sweep” was observed visually or on radar.)
By this time all the witnesses were greatly excited by the UFO. The master sergeant couldn’t decide what to do next because he kept thinking, “They’re bigger than all of us!” but the traffic controller notified the F-84 patrolling in the west and asked for an intercept. The pilot soon found the light, which was still stationary. He began the chase, but when he had approached to within an estimated three miles, the light rapidly began to retreat. He continued the chase directly north for 120 miles (during which both the jet and the UFO went off the ground scope) but he could not gain on the object. Running short of fuel, he turned back toward the base. The ground scope soon picked him up again and, a few seconds later, picked up an unknown target apparently trailing the jet by ten or fifteen miles.
A second jet then took to the air, located the light, and began the pursuit. Like the first pilot, he could not close the distance between him and the receding UFO. After performing various tests to convince himself that he wasn’t chasing a reflection, he finally turned on his radar gun camera. After a few seconds the red light blinked on, indicating a solid object ahead. The pilot thereupon asked permission to break off the intercept and, having taken a photograph, returned to base. As before, the ground scope picked up the returning jet but this time the UFO did not reappear on the scope. The controller then called officials at the filter center at Fargo, North Dakota. They had not received any UFO reports; a few minutes later, however, they called back to say that spotter posts between the two cities, on a southwest-northeast line, had indeed seen a bluish-white light.
Investigators from ATIC arrived promptly but they were not able to explain the sighting. Even the photographs showed nothing useful. Conclusion: unknown.
The incident remained unexplained chiefly because the investigators, like the witnesses, apparently assumed that a single unidentified flying object accounted for all the phenomena observed that evening. Although the available evidence is somewhat confusing, a careful study shows that, on the contrary, the visual and the radar targets could not have been the same.
When the ground spotter first reported the UFO, she described it as a stationary light low on the horizon. The radarscope, however, showed a target that was moving slowly, at an altitude of about 16,000 feet. Some minutes later, when the visual target did begin to move, the radar target speeded up. This was the only instance in which the movements of the two seemed to be roughly parallel. But in the excitement that followed, all the witnesses assumed that the two targets were identical. The published account[VIII-3, p. 303 ff.] does not distinguish clearly between the actions of the light and the movements of the blips on the radarscope.
Let us begin by reviewing the facts about the visual target. According to the witnesses on the ground, it was a brilliant bluish-white light that appeared on the northeast horizon and remained stationary during most of the period it was observed. At one time it seemed to advance rapidly toward the witnesses, make a wide sweep around Rapid City, which was a few miles away from the observers, and then return to its original position. According to the witnesses in the air, the light did not remain stationary but retreated from the pursuing plane and followed the returning plane, duplicating the plane’s speed and keeping the distance between them constant. The pilots based this interpretation, evidently, on the fact that the light did not vary in size or brilliance and thus seemed to pace the plane.
These descriptions all point to the same answer: that the light was a star or a planet. Since it was infinitely distant, the jets could not get any closer to it and at ground levels the image was distorted by peculiar atmospheric conditions. Mars had been absent from the night sky for months, and Mercury, Venus, and Jupiter were then morning stars; therefore the unknown could not have been a planet. However, the bright star Capella was on the northeast horizon at a declination of plus 46 degrees and would have been visible from both Fargo and Rapid City. A check of the Weather Bureau records shows that the night was clear and dark. The sun had set about an hour before the sighting began, and at that time in the evening there was no moonlight because the moon was in its last quarter. Visibility was about thirty-five miles and the wind was from the northeast, about four meters per second. There was a marked temperature inversion—9 degrees—at ground levels. Such an inversion could easily account for the erratic motions reported for the light.
There can be little doubt that the visual target was the star Capella.
The radar targets also were clearly the result of weather, just as the air-traffic controller had suspected when he first looked at the scope. Conditions were ideal—a calm, clear, warm summer night—for phantom echoes. The first radar target, moving southwest, was probably a return from some ground object. When the jet took to the air, the scope showed a different kind of UFO target, one that echoed the movements of the plane itself—retreating from the pursuer, advancing when the pursuer turned back—and was always farther away from the ground station than the plane itself.
Although saucer enthusiasts interpret these maneuvers as proof that the phantom was under intelligent control, radar experts recognize the familiar pattern in which a ghost echo is actually a return from the plane itself. Because of the temperature inversions the radar pulses do not return directly from the plane to the ground receiver but are deflected from the plane to the ground, then back to the plane, and thence on to the ground scope. The phantom echo always occurs from the same direction as the aircraft and is always “on the other side” of the plane (see p. 153).
This explanation also accounts for the evidence of the jet’s gun camera. The photographs taken showed nothing, although the radar warning light indicated a solid object ahead. After the pilot had switched on the set, however, there had been a brief delay before the red signal blinked on. During this interval the plane had not come any closer to the unknown light, but the radio waves had scattered from plane to ground and back to plane so that the gun radar did indeed detect a solid object—the plane itself!
In short, the evidence supports our conclusion that an image of the star Capella, distorted by the atmospheric conditions produced by a strong temperature inversion, accounted for the visual sightings; and that radar echoes from the pursuing jets, deflected by the same temperature inversion, accounted for the phantom targets on the ground radarscope and the gun radar.