Scientific Study of Unidentified Flying Objects

Director Dr. Edward U. Condon

1968 by the Board of Regents of the University of Colorado

Excerpts from Section III, Chapter 5, & Section IV, Chapter 1

[From Section III, Chapter 5, Optical and Radar Analyses of Field Cases, by Gordon D. Thayer, Environmental Science Services Administration.]


Case 2. Lakenheath, England, 13-14 August 1956, 2230-0330 LST. Weather: generally clear until 0300 LST on the 14th. (For details see Section IV.)

The probability that anomalous propagation of radar signals may have been involved in this case seems to be small. One or two details are suggestive of AP, particularly the reported disappearance of the first track as the UFO appeared to overfly the Bentwaters GCA radar. Against this must be weighed the Lakenheath controller's statement that there was "little or no traffic or targets on scope," which is not at all suggestive of AP conditions, and the behavior of the target near Lakenheath -- apparently continuous and easily tracked. The "tailing" of the RAF fighter, taken alone, seems to indicate a possible ghost image, but this does not jibe with the report that the UFO stopped following the fighter, as the latter was returning to its base, and went off in a different direction. The radar operators were apparently careful to calculate the speed of the UFO from distances and elapsed times, and the speeds were reported as consistent from run to run, between stationary episodes. This behavior would be somewhat consistent with reflections from moving atmospheric layers -- but not in so many different directions.

Visual mirage at Bentwaters seems to be out of the question because of the combined ground and airborne observations; the C47 pilot apparently saw the UFO below him. The visual objects do not seem to have been meteors; statements by the observers that meteors were numerous imply that they were able to differentiate the UFO from the meteors.

In summary, this is the most puzzling and unusual case in the radar-visual files. The apparently rational, intelligent behavior of the UFO suggests a mechanical device of unknown origin as the most probable explanation of this sighting. However, in view of the inevitable fallibility of witnesses, more conventional explanations of this report cannot be entirely ruled out.

[From Section IV, Chapter 1, Case Studies Predating the Term of the Project]

Case 2


Summer 1956

Investigator: Staff


At least one UFO was tracked by air traffic control radar (GCA) at two USAF-RAF stations, with apparently corresponding visual sightings of round, white rapidly moving objects which changed directions abruptly. Interception by RAF fighter aircraft was attempted; one aircraft was vectored to the UFO by GCA radar and the pilot reported airborne radar contact and radar gunlock., The UFO appeared to circle around behind the aircraft and followed it in spite of the pilot's evasive maneuvers. Contact was broken when the aircraft returned to base, low on fuel. The preponderance of evidence indicates the possibility of a genuine UFO in this case. The weather was generally clear with good visibility.


The existence of this very interesting radar-visual case was first brought to the attention of the project staff in winter 1968 by the receipt of an unsolicited letter from one of the principal witnesses, a retired USAF non-commissioned officer who was the Watch Supervisor at the GCA station on the night in question. This letter is rather well written, and since it forms the most coherent account of this UFO case, it is reproduced below in its entirety.

Reference your UFO Study: you probably already have this item in your file, but, in case you don't, I will briefly outline it and you can contact me for full details if you want them.

I retired (20 years service)...from the USAF. I have placed my name, rank, and serial number at the top of the page if you want to check on my authenticity. I was an Air Traffic Controller throughout my service career and utilized radar the last 16 years in the control of Air Traffic. I won't bother listing the types and locations, although I could supply all this if needed.

In 1956,...(I can't remember the exact date or month), I was on duty as Watch Supervisor at... [GCA A] in the Radar Air Traffic Control Center. It was the 5:00 p.m. to midnight shift. I had either four or five other controllers on my shift. I was sitting at the Supervisor's Coordinating desk and received a call on the direct line (actually I'm not sure which line it was). Anyway, it was... [GCA B] calling and the radar operator asked me if we had any targets on our scopes traveling at 4,000 mph. They said they had watched a target on their scopes proceed from a point 30 or 40 miles a point 40 miles west of...[GCA B]. The target passed directly over... [GCA B] RAF Station (also an USAF Station). He said the tower reported seeing it go by and it just appeared to be a blurry light. A C-47 flying over the base at 5,000 feet altitude also reported seeing it as a blurred light that passed under his aircraft. No report as to actual distance below the aircraft. I immediately had all controllers start scanning the radar scopes. I had each scope set on a different range-from 10 miles to 200 miles radius of... [GCA A]. At this time I did not contact anyone by telephone is I was rather skeptical of this report. We were using full MTI on our radar, which eliminated entirely all ground returns and stationary targets. There was very little or no traffic or targets on the scopes, as I recall. However one controller noticed a stationary target on the scopes about 20 to 25 miles southwest. This was unusual as a stationary target should have been eliminated unless it was moving at a speed of at least 40 to 45 knots. And yet we could detect no movement at all. We watched this target on all the different scopes for several minutes and I called the GCA Unit at ... [A] to see if they had this target on their scopes also. They confirmed the target was on their scope in the same geographical location. As we watched, the stationary target started moving at a speed of 400 to 600 mph in a north, northeast direction until it reached a point about 20 miles north northwest of ... [A]. There was no slow start or build-up to this speed--it was constant from the second it started to move until it stopped.

I called and reported all the facts to this point, including... [B] GCA's initial report, to the ...Command Post... ...I also hooked in my local AFB Commanding Officer and my Unit (AFCS Communications Squadron) Commander on my switchboard. And there could have been others hooked in also that I was not aware of. I repeated all the facts known to this point and continued to give a detailed report on the target's movements and location. The target made several changes in location, always in a straight line, always at about 600 mph and always from a standing or stationary point to his next stop at constant speed--no build-up in speed at all--these changes in location varied from 8 miles to 20 miles in length--no set pattern at any time. Time spent stationary between movements also varied from 3 or 4 minutes to 5 or 6 minutes (possibly even longer as I was busy answering questions--listening to theories, guesses, etc. that the conference line people were saying). This continued for some time. After I imagine about 30 to 45 minutes, it was decided to scramble two RAF interceptors to investigate. This was done I believe by Air Force calling the RAF and, after hearing what the score was, they scrambled one aircraft. (The second got off after as I will mention later.)

The interceptor aircraft took off from an RAF Station...and approached... [A] from the southwest. Radio and radar contact was established with the RAF intercept aircraft at a point about 30 to 35 miles southwest...[and] inbound to...[A]. On initial contact we gave the interceptor pilot all the background information on the UFO, his (the interceptor's) present distance and bearing from... [A], the UFO's (which was stationary at the time) distance and bearing from... [A]. We explained we did not know the altitude of the UFO but we could assume his altitude was above 15,000 feet and below 20,000 feet, due to the operational characteristics of the radar (CPS-5 type radar, I believe). Also we mentioned the report from the C-47 over . . . [B] that relayed the story about the light which passed below him. His altitude was 5,000 feet.

We immediately issued headings to the interceptor to guide him to the UFO. The UFO remained stationary throughout. This vectoring of the intercept aircraft continued. We continually gave the intercept aircraft his heading to the UFO and his distance from the UFO at approximately 1 to 2 mile intervals. Shortly after we told the intercept aircraft he was one-half mile from the UFO and it was twelve-o'clock from his position, he said, "Roger, ...I've got my guns locked on him." Then he paused and said, "Where did he go? Do you still have him?" We replied, "Roger, it appeared he got behind you and he's still there." [There were now two targets; one behind the other, same speed, very close, but two separate distinct targets.]

The first movement by the UFO was so swift (circling behind the interceptor); I missed it entirely, but it was seen by the other controllers. However, the fact that this had occurred was confirmed by the pilot of the interceptor. The pilot of the interceptor told us he would try to shake the UFO and would try it again. He tried everything--he climbed, dived, circled, etc. but the UFO acted like it was glued right behind him, always the same distance, very close, but we always had two distinct targets. [Note: Target resolution on our radar at the range they were from the antenna (about 10 to 30 miles, all in the southerly sectors from... [A]) would be between 200 and 600 feet probably. Closer than that we would have got one target from both aircraft and UFO. Most specifications say 500 feet is the minimum, but I believe it varies and 200 to 600 feet is closer to the truth and, in addition, the tuning of the equipment, atmospheric conditions, etc., also help determine this figure.]

The interceptor pilot continued to try and shake the UFO for about ten minutes (approximate -- it seemed longer both to him and us). He continued to comment occasionally and we could tell from the tonal quality he was getting worried, excited and also pretty scared.

He finally said, "I'm returning to Station, .......[A]. Let me know if he follows me. I'm getting low on petrol." The target (UFO) followed him only a short distance, as he headed south southwest, and the UFO stopped and remained stationary. We advised the interceptor that the UFO target had stopped following and was now stationary about 10 miles south of...[A] He rogered this message and almost immediately the second interceptor called us on the same frequency. We replied and told him we would advise him when we had a radar target, so we could establish radar contact with his aircraft. (He was not on radar at this time, probably had just taken off and was too low for us to pick him up, or too far away--we had most of the scopes on short range, so we could watch the UFO closely on the smaller range.) The number two interceptor called the number one interceptor by name (Tom, Frank--whatever his name was) and asked him, "Did you see anything?" Number one replied, "I saw something, but I'll be damned if I know what it was." Number two said, "What happened?" Number one said, "He (or it) got behind me and I did everything I could to get behind him and I couldn't. It's the damnedest thing I've ever seen." Number one also made a remark at this time to number two, that he had his radar locked on whatever it was for just a few seconds so there was something there that was solid. Number one then switched frequencies to his home base frequency. We gave number two the location of the UFO and advised him that we still didn't have him on radar, but probably would have shortly. He delayed answering for some seconds and then finally said, . . . [A] _________ (Identification aircraft call sign)--can't remember what call sign these aircraft were using. Returning home, my engine is malfunctioning." He then left our frequency.

Throughout this we kept all the agencies, ... advised on every aspect, every word that was said, everything.

We then inquired what action they wanted to take. They had no more suggestions and finally they told us to just keep watching the target and let them know if anything else happened. The target made a couple more short moves, then left our radar coverage in a northerly direction -- speed still about 600 mph. We lost target outbound to the north at about 50 to 60 miles, which is normal if aircraft or target is at an altitude below 5,000 feet (because of the radiation lobe of that type radar). We notified . . . Air Division Command Post and they said they'd tell everybody for us.

I made out a written report on all this, in detail for the officers in charge of my facility, and was told that unless I was contacted later for further information, he would take care of it. I don't know if a CERVIS report was submitted on this or not--I heard no more about it.

All speeds in this report were calculated speeds based on time and distance covered on radar. This speed was calculated many times that evening and although this happened quite awhile ago, the basic elements are correct.

Fig. 1 shows a map of the contact as drawn by the witness.


Since this case was discovered so late in the project, investigation was limited to a follow-up request for additional information from Project Blue Book, and analysis of the available details of the case by investigators familiar with radar and optical propagation anomalies.

Copies of the Project Blue Book files on the case were received in late August of 1968. A considerable amount of this material is reproduced below. One of the interesting aspects of this case is the remarkable accuracy of the account of the witness as given in the letter reproduced above, which was apparently written from memory 12 yr. after the incident. There are a number of minor discrepancies, mostly a matter of figures (the C-47 at 5,000 ft. was evidently actually at 4,000 ft.), and he seems to have confused the identity of location C with B; however, all of the major details of his account seem to be well confirmed by the Blue Book account.

There were ancillary sightings at .   .   . [C] besides those which instigated the UFO search by the .   .  . [A] GCA Unit but as subsequent airborne intercept attempts yielded neither radar nor visual contact, these accounts are not detailed below.

Figure 1: USAF/RAF Radar Sighting

At 22557, ...[C] GCA sighted object thirty miles east of station traveling westerly at 2000-4000 mph. Object disappeared on scope two miles east of station and immediately appeared on scope three miles west of station where it disappeared thirty miles west of station on scope. Tower personnel at .... [C] reported to GCA a bright light passed over the field east to west at terrific speed and at about 4000 feet alt. At same time pilot in aircraft at 4000 feet alt. over.... [C] reported a bright light streaked under his aircraft traveling east to west at terrific speed. At this time.... [C] GCA checked with RAF station.... [A] GCA to determine if unusual sightings were occurring ....[A] GCA alerted [the] AAA stationed at ....[A] and ....[B] GCA to watch for unusual targets. Following info is the observations made by this station radar, tower and ground personnel placed in format required by AFR 2000-2: 1. Description of object(s): (A) Round white lights (B) One observer from ground stated on first observation object was about size of golf ball. As object continued in flight it became a "pin point." (C) Color was white. (D) Two from ground observation undetermined number of blips appearing and disappearing on radar scopes. (E) No formation as far as radar sightings concerned. Ground observers stated one white light joined up with another and both disappeared in formation together. (F) No features or details other then the white light. (C) Objects as seen by ground observers and GCA radar have feature of traveling at terrific speeds and then stopping and changing course immediately. 2. Description of course of objects: (A) Ground observers looked at sky and saw the object(s). RAF Station .... [Al GCA was alerted by .... [C] GCA to be on lookout for unusual targets. (B) Ground observers estimated objects were 20-2500 feet alt and were on a SW heading. Object stopped and immediately assumed an easterly heading. RAF Station .... [A] GCA and Air Traffic Control Center reports radar tracking from 6 miles west to about twenty miles SW where target stopped and assumed a stationary position for five minutes. Target then assumed a heading north westerly into the Station and stopped two miles NW of Station. ....[Al GCA reports three to four additional targets were doing the same. Radars reported these facts to occur at later hours than the ground observers. (C) Ground observers report no change in alt and objects disappeared on easterly heading. Radar sets stated no definite disappearance factors other than targets disappeared from scopes at approx 0330 GMT Aug 14. (D) Flight path was straight but jerky with object stopping instantly and then continuing. Maneuvers were of same pattern except one object was observed to "lock on" to fighter scrambled by RAF and followed all maneuvers of the jet fighter aircraft. In addition, ....[A] Radar Air Traffic Control Center observed object 17 miles east of Station making sharp rectangular course of flight. This maneuver was not conducted by circular path but on right angles at speeds of 600-800 mph. Object would stop and start with amazing rapidity. (B) Objects simply disappeared. (F) Objects were observed intermittently by RAF Station....[A] radars from 140310 to 140330. 3. Manner of observation: (A) Ground-visual, air-electronic and ground-electronic. Ground-electronic equipment was TS-ID, CPS 5, and CPN4 radars. Air-electronic was A-l airborne radar equipment in ....jet aircraft. Type of aircraft, Venom, operating out of RAF Station .... 4. Time and date of sighting: (A) Summer 140010Z through 140330Z. (B) Night (sky clear and nin/th of clouds--moonlight). 5. Location of observers RAF Station .... [A] 52o24'N 0o33'E. 6. Weather and winds-aloft conditions at time and place of sightings: (A) Clear sky until 0300Z shortly thereafter scattered clouds at 3500 ft. (B) From midnight until 0600Z surface wind was 230 deg at 15 knots; 6000 ft 290 deg at 24 knots; 1000 ft 290 deg at 35 knots; 16,000 ft 290 deg at 45 knots; 20,000 ft 290 deg at 53 knots; 30,000 ft 290 deg at 62 knots; 50,000 ft 290 deg at 75 knots. (C) Ceiling unlimited. (D) Visibility from OOOlZ to 04000Z was 10 nautical miles. (F) 1/10 of sky covered at 0300Z. 8. Ground observers report unusual amount of shooting stars in sky. Further state the objects seen were definitely not shooting stars as there were no trails behind as are usual with such sightings. 9. Interception was undertaken by one British jet fighter on alert by.... [A] sector control. Aircraft is believed to have been a Venom. The aircraft flew over RAF Station ... [A] and was vectored toward a target on radar 6 miles east of the field. Pilot advised he had a bright white light in sight and would investigate. At thirteen miles west he reported loss of target and white light. ....[All RATCC vectored him to a target miles east of .. ..[A] and pilot advised target was on radar and he was 10 "Pilot reported he had lost target on his radar. ....[A] RATCC reports locking on." that as the Venom passed the target on radar, the target began a tail chase of the friendly fighter. RATCC requested pilot acknowledge this chase. Pilot acknowledged and stated he would try to circle and get behind the target. Pilot advised he was unable to "shake" the target off his tail and requested assistance. One additional Venom was scrambled from the RAF Station. Original pilot stated; "ever seen on radar." Target disappeared and second aircraft clearest target I have did not establish contact. First aircraft returned to home Station due to being low on fuelVenom was vectored to other radar targets but was unable to . Second make contactShortly afterwards, second fighter returned to home Station due to . malfunctionsNo further interception activities were undertaken. All targets . disappeared from scopes at approximately 0330Z. 10. Other aircraft in the area were properly identified by radar and flight logs as being friendly. All personnel interviewed and logs of RATCC lend reality to the existence of some unexplainable flying phenomena near this air field on this occasion. Not an Air Base; however, the controllers are experienced and technical skills were used in attempts to determine just what the objects were. When the target would stop on the scopewas used. However, the target would still appear on the . The MTI scopeobservers and reports from observers at ....[C] agree on color. . All ground Maneuvers and shape of object. My analysis of the sightings is that they were real and not figments of the imagination. The fact that three radar sets picked up the targets simultaneously is certainly conclusive that a target or object was in the air. The maneuvers of the object were extraordinary; however, the fact that radar and ground visual observations were made on its rapid acceleration and abrupt stops certainly lend credence to the report. It is not believed these sightings were of any meteorological or astronomical origin.

The material on the .... [C] sightings given at the beginning of the preceding account is typical; three other radar targets tracked by that station behaved in a similar manner and intercept attempts made from 2130 to 2215 GMT by an American T-33 jet aircraft were fruitless.

An analysis of this case from the viewpoint of possible anomalous propagation was made and appears in Chapter 7.


In view of the multiple radar sightings involved in this case, any conventional explanation for the occurrences reported would seem to require some sort of radar anomalous propagation. As pointed out in Chapter 7, the evidence for anomalous propagation in this case is rather uncertain. The temporary disappearance of the target as it appeared to overfly the ....[C] GCA is quite suggestive of anomalous propagation. The generally clear weather was conducive to the formation of the atmospheric stratification that causes anomalous propagation, although it by no means follows that such formation would have actually occurred. In this connection, the apparent near-coincidence between the appearance of broken clouds (0330 GMT) and the disappearance of the radar targets (0330 GMT) could be significant.

On the other side must be balanced the generally continuous and consistent movements of the radar tracks reported by . . .[A], which are not at all typical of radar false targets caused by anomalous propagation. In addition, some of the maneuvers reported in the radar controller's letter to have been executed by the UFO are extremely unlikely to be duplicated by a false target, in particular stopping and assuming a new path after following the intercepting aircraft for some time. The comments of the Air Force officer who prepared the UFO message reproduced earlier are also significant.

In an early Air Force investigation it was suggested that the visual sightings might have been caused by the Perseid meteors. However, as Air Force Consultant Dr. Hynek pointed out:

It seems highly unlikely, for instance, that the Perseid meteors could have been the cause of the sightings, especially in view of the statement of observers that shooting stars were exceptionally numerous that evening, thus implying that they were able to distinguish the two phenomena. Further, if any credence can be given to the maneuvers of the objects as sighted visually and by radar, the meteor hypothesis must be ruled out.

Dr. Hynek also remarked:

The statement that radars reported these facts to occur at later hours than the ground observers' needs clarification inasmuch as it contradicts other portions of the report which indicate that at least at certain times visual and radar sightings were simultaneous.

In retrospect it appears that what the statement in question may have been meant to imply was that the radars continued to report target(s) after visual contact had been lost; the statement does not necessarily imply that no simultaneous radar-visual sightings occurred.

In conclusion, although conventional or natural explanations certainly cannot be ruled out, the probability of such seems low in this case and the probability that at least one genuine UFO was involved appears to be fairly high.

Note: The Final Report of the Scientific Study of Unidentified Flying Objects was originally copyrighted in 1968 by the Regents of the University of Colorado, a body corporate. It was subsequently published in reports of the United States Air Force and other governmental agencies and was published commercially by Bantam Books (currently out of print).

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