Gordon D. Thayer (NOAA)
: Astronautics & Aeronautics, pp. 60-64,
: Astronautics & Aeronautics, pp. 60-64, : Astronautics & Aeronautics, pp. 60-64, 
The following story ? an example of the type of observation which forms the core of the UFO issue ? has been selected by the UFO Subcommittee of the AIAA for publication not only because of its puzzling content, but also because of the multiplicity of observations. The author, a former member of the "Condon Committee" (University of Colorado UFO study team), discusses the case, but does not offer an explanation. This case study is intended to give the reader a flavor of the observational residue material which underlies the UFO controversy. We hope he will give it his independent assessment as engineer or scientist.
On a pleasant August evening in en , the night-watch supervisor at the Lakenheath, England, Radar Air
Traffic Control Center (RATCC), a U.S. Air Force noncommissioned officer, was startled by a telephone call from the
Bentwaters GCA (Ground Controlled Approach) radar installation (see map) asking, Do you have any targets on your
scopes traveling at 4000 mph ?
Thus began one of the strangest and most disturbing radar-visual UFO episodes on
record.
There is a very large, confusing report on the Lakenheath-Bentwaters incident in the U.S. Air Force Project Bluebook files (Project Bluebook was the name of the U.S. Air Force UFO investigation). At least three separate times unidentified radar echoes (UREs) were tracked by the GCA unit at Bentwaters before the telephone contact with Lakenheath; and although these are highly interesting events in themselves, they did not involve confirmatory visual and airborne radar contacts. A detailed account of these first three radar contacts can be found in an earlier paper by James McDonald (FSR 16, "UFOs over Lakenheath in 1956," 1970, pages 9-17), "Scientific Study of Unidentified Flying Objects", (Bantam Books, 1969; hereafter refered to as the "Condon Report") contains no account of these because the pertinent Bluebook files were obtained too late for inclusion. The Condon Report does contain an independent account of the primary incident at Lakenheath, as reported by the night-watch supervisor, not found in the Bluebook file; this separate report forms the most coherent account of the events at Lakenheath.
Following a brief description of the events at Bentwaters based on the Bluebook file, the Lakenheath incident will be described here based mainly on the night-watch supervisor's account.
The four events at Bentwaters GCA took this order:
The size of the blip when picked up was that of a normal aircraft target.[It]
diminished in size and intensity to the vanishing point before crossing the entire radar screen.
few minutes later, say roughly 21:35Z, a group of 12-15 UREs was picked up on the PPI about 8 mi. SW of Bentwaters (No. 2 in map). These echoes
appeared as normal targets, and
normal checks made to determine possible malfunctions of the GCA radar failed to indicate anything was technically wrong.These URE's appeared to move as a group toward the NE at varying speeds reported as 80-125 mph. The group covered a "6-7-mi. area" on the scope. These echoes
faded considerablyat a point 14 mi. NE of Bentwaters, but were tracked to a point about 40 mi. NE of Bentwaters when they merged into a single strong echo
several times larger than a B-36 return under comparable conditions.This single echo remained stationary at the point 40 mi. NE of Bentwaters for 10- 15 min., then moved to the NE for 5-6 mi., stopped again for 3-5 min., and finally moved out of range (50 mi.) of the radar at 21:55Z. The average apparent speed of the URE group for the time it was in motion can be readily calculated as between 290 and 700 mph (58 mi. in 5-12 min ? again differing from the operator's estimate.
in excess of 4000 mphbut the time and distance figures indicated a speed of roughly 12000 mph. All the returns
appeared normal, except for the last, which was slightly weaker than the rest. The radar operator indicated that the
[return] disappeared ... by rapidly moving out of the GCA radiation pattern.No further UREs are mentioned in the Bluebook report on the Bentwaters incident; and considering the confusion prevailing in reported times in Bluebook reports and the similarity of the reported tracks and speeds, possibly this URE and No. 4, which instigated the phone call to Lakenheath, may in fact be the same.
2000 to 4000 mph.In the map shown at right, the track of the URE appears identical with No. 3 except for the vanishing point. This URE then
disappeared on scope 2 mi. east of station and immediately appeared on scope 3 mi. west of station ... it disappeared 30 mi. west of station on scope.If the word
immediatelymeans that the URE was picked up on the same PPI sweep, after 180 deg. rotation from east to west, it would imply that the apparent motion covered 5 mi. in 1 sec, an inferred speed of some 18000 mph. At this rate the URE would have covered the 60 mi. track in about 12 sec (6 PPI sweeps). As pointed out, this may have been URE No. 3 from the Bentwaters Bluebook report, which is estimated at 12000 mph, although the reported times are different .
At this point, someone at the Bentwaters GCA station called the Lakenheath RATCC station asking the night-watch
supervisor there if he had any 4000-mph targets
on his Scopes and describing the track of URE No. 4. The caller
stated that the control tower at Bentwaters had reported seeing a bright light passing over the field from east to
west at terrific speed at about 4000-ft altitude
, while at the same time the pilot of a C-47 aircraft flying
over the station at 4000-ft altitude reported a bright light streaked under his aircraft traveling east to west at
terrific speed
. The Lakenheath watch supervisor, although admittedly skeptical of this report, immediately
had all controllers start scanning the radar scopes ... using full MTI (moving target indicator), which eliminated
entirely all ground returns.
Shortly after this search began, one of the controllers noticed a stationary echo on the scopes at an indicated
position 20-25 mi. SW of Lakenheath. Note the position of this initial contact on the map; it is almost directly in
line with the path of UREs 3 and 4 from the Bentwaters report. Although the MTI should have eliminated the return from
any target moving at less than 40-50 knots, the radar personnel could detect no movement at all
from this URE.
The watch supervisor called the GCA unit at Lakenheath to see if they had the same echo on their scope and they
confirmed the target was on their scope in the same location.
As the Lakenheath RATCC personnel watched this
URE, it suddenly began moving in a NNE direction at a speed that they subsequently calcuIated to be 400-600 mph. In
their words there was no ... build-up to this speed ? it was constant from the second it started to move until it
stopped.
The watch supervisor contacted local AFB command personnel and kept them informed of the happenings from this point on. The URE made several changes in direction always in a straight line, always at about 600 mph with no accelerstion or deceleration apparent ? the changes varying in indicated length from 8 to 20 mi., with stationary episodes of 3-6 min intervening.
There were visual sightings at Lakenheath during this time, but the reports of these are confusing and inconclusive.
Perhaps of greater significance are the investigating officer's statements that 2 radar sets [Lakenheath GCA and
RATCC] and three ground observers report substantially the same
, and the fact that radar and ground visual
observations were made on its rapid acceleration and abrupt stops certainly lend
[credence] to the report
.
After about 30-45 min
, or 23:40 to 23:55Z, the RAF scrambled
a de Havilland "Venom" night fighter
aircraft to investigate the Lakenheath UFO.
(At this point, the account of the Lakenheath night-watch supervisor and that of the Project Bluebook report diverge. First, the watch supervisor says the aircraft was from a field near London and was picked up on the RATCC radar inbound from the southwest at a range of 30-45 mi. from Lakenheath. According to the Bluebook file, the fighter took off from Waterbeach RAF station (see map), which is only 20 mi. SW of Lakenheath and well within radar range ? given as 50-60 mi. for targets at 5000 ft or above. Second, the watch supervisor relates that the Venom was vectored to the then stationary URE (No.5) at a position about 16 mi. SW of Lakenheath, and that this was the aircraft's first and only contact with any UFO. According to the Bluebook account, "the a/c flew over Lakenheath and was vectored to a radar target 6 mi. east of the field (No. 6). Pilot advised he had a bright white light in sight and would investigate. At 13 mi. west [of Lakenheath] he reported loss of target and white light [N.B. ? this implies that the pilot had the unknown on his airborne radar as well as having had visual contact]. Lakenheath RATCC vectored him to (presumably) another target 10 mi. east of Lakenheath and pilot advised target was on radar and he was "locking on." This target would be URE No. 5, identified by the watch supervisor as being about 16 mi. SW of Lakenheath. Except for this discrepancy, the account of the Lakenheath watch supervisor agrees with the Bluebook file from here on in virtually every detail.)
The Venom fighter was vectored by the RATCC radar to the sight of the URE, which (according to the night-watch
supervisor) was stationary at the time at 15000-20000 ft about 16 mi. SW of Lakenheath. Shortly after Lakenheath told
the pilot the URE was one-half mile dead ahead of the interceptor, the pilot radioed, Roger, ... I've got my guns
locked on him.
(The pilot refers to a radar fire-control system.) This pilot later told a U.S. Air Force
investigator that the URE was the clearest target I have ever seen on radar.
There was a brief pause after the
Venom pilot said he had gunlock on the URE and then he said, Where did he go ? Do you still have him ?
The
Lakenheath RATCC informed him that the URE had made a swift circling movement and had gotten behind the Venom. The
pilot then confirmed that the target was behind him and said that he would try to shake it. Since no tail radar is
mentioned, the pilot presumably saw the UFO behind him.
|
|
||||
| No. | Time | Radar contacts | Visual contacts | Remarks |
|
|
||||
| 1 | 2130 Z | Bentwaters GCA, AN/MPN-11A. | Not confirmed. | Not AP. |
| 2 | ~2135?2155 Z | Bentwaters GCA. | Not confirmed. | Possible AP. |
| 3 | 2200 Z | Bentwaters GCA. | Not confirmed. | Not AP; possibly as No. 4. |
| 4 | 2255 Z |
|
|
Not AP; No. 5 could have been same "object." |
| 5 | 0010?0330 Z |
|
Ground observations not confirmed.
|
Not AP or radar malfunction; may have been No. 4 from Bentwaters. |
|
|
||||
The pilot of the Venom interceptor tried numerous evasive maneuvers, but he was unable to lose the URE, which the
Lakenheath RATCC radar continuously tracked as a distinct echo behind the aircraft echo; this implies that the
separation was greater than about 500 ft. According to the Bluebook report, Pilot advised he was unable to `shake'
the target off his tail and requested assistance.
After about 10 min., the first Venom pilct, who reportedly
sounded pretty scared
, said that he was returning to base because he was running low on fuel. He asked
Lakenheath RATCC to tell him if the URE followed him on the radar scopes. According to the Lakenheath watch
supervisor, the URE appeared to follow the Venom only a short distance
as the pilot headed SSW toward London
[or Waterbeach], and then it resumed a stationary aspect.
A second Venom was vectored by Lakenheath RATCC toward the position of the URE; but before he got close enough to pick up anything, he radioed that he W.lS experiencing engine malfunction and was returning to his base. The following conversation was monitored by the Lakenheath watch supervisor between the 2 Venom pilots :
Number 2: Did you see anything ?
Number 1: I saw something, but I'll be damned if I know what it was.
Number 2: What happened ?
Number 1: 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 l've ever seen.
The pilot of Venom Number 1 also stated that he had radar gun lock for several seconds so there was something
there that was solid.
Following this strange "chase," the URE did not immediately disappear from the Lakenheath RATCC radar. In the words
of the nightwatch supervisor, 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 50-60 mi., which is
normal if aircraft or target is at an altitude below 5000 pieds (because of the radiation lobe of that type radar [a
CPS-5]).
The time of loss of contact was not given by the watch supervisor; according to the Bluebook file the
time was about 03:30Z.
The night-watch supervisor also stated all speeds in this report were calculated speeds based on time and distance
covered on radar. This speed was calculated many times that evening...
The interpretations and analyses that have been made of this intriguing UFO incident are almost as numerous as the investigators themselves. The investigating U.S. Air Force officer wrote: "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." We quote this statement. although these are hardly the words of a careful, scientific investigator.
J. Allen Hynek, the well-known UFO consultant to the Air Force, wrote in part It seems highly unlikely, for
instance, that the Perseid meteors could have been the cause of the sightings, especiaily in view of the statement of
observers that shooting stars were exceptionally numerous that evening, thus plying 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.
The Condon Report in its analysis of this incident states: 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 gwnuine UFO was involved appears to be faars th ie fairly high.
The meaning of this last
statement has puzzled some later investigators; in this context a "genuine UFO" was meant to imply precisely that :
there was a material object, it was flying (in the sense of moving through the air), and it was (obviously)
unidentified. It was not meant to imply, for example, that the UFO was necessarily of extraterrestrial origin.
In Chapter 5 of the Condon Report, Optical and Radar
Analyses of Field Cases, the analysis of this report concludes with: 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.
Philip Klass believes that the Lakenheath RATCC radar was malfunctioning because of a faulty MTI unit; he feels that once the radar evidence has been explained, the rest can be accounted for by either confusion of witnesses or conventional causes.
The reader may draw his own conclusions as to which of the above "explanations" seems the most likely. However, a few things are worth pointing out in summary:
The "disappearance" of URE No. 4 as it overflew the Bentwaters GCA station was mentioned in the Condon Report as
being suggestive of AP
[anomalous propagation], and so it is. The elevated-layer partial reflection phenomenon
that causes this type of AP involves a reflection coefficient that is typically proportional to the inverse sixth
power of the elevation angle of the radar beam (cf. Wait, 1962; Thayer 1970). Thus caused by a moving layer, if such a false target appears to
approach the radar site, the signal will drop below the noise level when the beam elevation exceeds some critical
angle; the false target will often reappear on the other side of the radar when the beam angle once more drops below
the critical value. With a fixed-elevation PPI display radar. this results in a "zone of invisibility" around the site
with a radius on the order of 5-15 mi. in which the target disappears.
Two additional factors seem to point to AP as a possible cause for URE No.4 :
However, a strong factor argues against the AP hypothesis in this instance: the URE was moving almost opposite to the prevailing winds. In addition, because of the apparent speed of the URE, it should have reappeared about 3.5 mi. west of the radar on the second PPI sweep after "losing" it 2 mi. east (on the first sweep it should have been almost over the radar, and probably not visible to it), so that the "asymmetry" can be assigned to the "digital" sampling by the PPI sweep-scan display. It is therefore most unlikely that URE No. 4 was caused by AP, a conclusion also reached in the Condon Report.
The Lakenheath episode (URE No. 5) is even more unlikely to have been caused by AP. That the complicated, stop-and-go maneuvers described by the Lakenheath nightwatch supervisor could have been caused by AP returns, and at that on two different radars operating on different frequencies and scan rates, is almost inconceivable. Ghost echoes have often been observed that will appear to "tail" an aircraft echo ? sometimes the radar will even track a jet-exhaust plume ? but such echoes never stop following the aircraft and become stationary, as did the Lakenheath URE.
In summary, although AP may possibly have been a factor in the No. 2 Bentwaters sighting, it is not possible to assign the rest of the events reported to propagation effects, even aside from the visual confirmations.
Possible malfunction of radar equipment, and especially possible malfunction of the MTI on the Lakenheath RATCC radar, has been suggested as a cause of these UREs. It is true that a malfunctioning MTI unit could conceivably produce false echo behavior similar to that observed at Lakenheath. However, the coincident observation of the URE by the Lakenheath GCA radar, a different type, and later by the Venom's airborne radar, seems to rule out this hypothesis. The detection of an apparently stationary target while the radar was on MTI is not as surprising as it seems. A vibrating or rapidly rotating target will show up on MTI radar even if it is not otherwise in motion.
Thus, none of the conceivable "simple" explanations for the events at Bentwaters and Lakenheath seems to hold up under investigation. Moreover, the credibility of the accounts is increased by the number of redundant radar and visual contacts made coincidentally. The table [at the end of this text] summarizes these redundancies, which are seen to be present primarily for events No. 4 and 5 (Bentwaters URE-UFO No. 4 and the Lakenheath UFO).
One slightly disturbing aspect of these contacts is that the Lakenheath RATCC radar operators failed to "pick up" Bentwaters UREs I through 4, even though they should have been well within range. (A target at 5,000 ft, for example, should have been visible anywhere west of the coastline in the vicinity of Bentwaters). Note that URE No. 1 was headed almost directly at Lakenheath at the time it was lost by Bentwaters GCA. Of course, it is possible that the radar did pick up these objects and that, for various possible reasons, the operators did not notice or report them.
In conclusion, with two highly redundant contacts ? the first with ground radar, combined with both ground and airborne visual observers, and the second with airborne radar, an airborne visual observer, and two different ground radars ? the Bentwaters-Lakenheath UFO incident represents one of the most significant radar-visual UFO cases. Taking into consideration the high credibility of information and the cohesiveness and continuity of accounts, combined with a high degree of "strangeness," it is also certainly one of the most disturbing UFO incidents known today.
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