PROJECT BLUE BOOK

' et

=

AU:He C3, AVC
BY: N.R Rosengarten

. UNCLASSIFIED Deter 11 Dec 5).

ig susceptatle to having ite radiated beam bent by "anonalous propagation" which
effccts the radar boa” et anglesthich ara nearly tangent to the "duct" layer.

The effects reported by the radar station, 663rd Aircraft and “arning Squadron,
located at the Hedhee=Tyson Aire aft, Knoxville, Tennessee on the nights of 29 and
3) Now 1950, are considered to be dus to a ratier mild (compared tr the same effects
observed on this type equipment at other locations) "duct" effect. |

Yajor Steel, AC Procurement and Security officor on the NUPA project was advised
to arrange with tho weather station at Sak Ridce to have atmospheric soundinys of
tenperature and huaidity made during subsequent occurrences of the "duct" phenomenon.
The Cak Ridge weather station has the nocessary equipment, a captive balloon wire sonje,
to make these soundings. Such soundings were not available for the period of detection
of unknown radar targets. It wee also recomended that equipment be requisitioned
making radar scope photographs of subsequent occurrences of the detection of unknown
targets, photon to be made at one-two sinute intervals.

It is of interest to note that flights of ducks have heen Getected on the AN/C?S=1
radar set at this Locotion and intercept aircraft have intercepted thie tyce targ:t.
Ducks wore detected at an »1titude of 6900 fect.

Tt appears that several individuals et Cak Ridce wore extre ely concerned wit’: the
possible tio-in between earlier incidents especially one regarding ea report received
from a féfmer Cak ‘idge trooper to the effect that he had aided two ren and a worn having

UNCLASSIFIED.

= 200, AYC

RY | elle
UNCLASSIFIED “a hie

difficulty with a truck in the mountains in the Sak Ridge area on 30 Var 1959,

' It was stated that this truck was on a seldom used road and was carrying 4 partially
covered silver colored cylindrical object. The occupants reportedly epoke with
a foreign accent. However, from the standpoint of technical intelligence, it
appeare that there is no relation between the two incidents. There are no olectronic
counterneasures known to this departront that would cause such radar targets ao
those reported on 29 «nd 30 November 1950, , |

UNCLASSIFIED

Roy Le Jamces MC TAX?
J.d.''odgers “CTALA-la

ee til

ett AN i

CODE FOR USE IN INDIVIDUAL PARAGR ALUATION

SUBJECT
UNIDENTIFIED OBJECTS ON RADAR SCOPES | or sounct: OF INFORMATION:
AT MoGHES TYSON AIRPORT, KNOXVILLE, COMPLETELY RELIABLE . 5 » « « - CONFIRMED BY OTHER SOURCES . .
TENNESSEE. — 4- COE. cc cac) | «QMO Lc cccel.

nas 8 6 8 68 a> eas Cas F&F 8 8 Be 86 € &

YY coCc “n“ .-  @e=_ "mu. Gua © FF €§ 8 8 8 SG

eo ‘ee. Cue

(In complience with letter AJACI~360.35 General, dated 15 November 1950,

Headquarters, Third Arny, sikmerts Uneonventional Aircraft, the following is
submitted. )

SUMMARY OF INFORMATION

Ae Location and Time of Si 3
i755 through 2400 i on 29 November 19603 0000 through 0500,

1361 through 14065, and 1630 hours through 2530, on &) November 1950.

Weather at the Times
ear, rature near freezing, and weather as described below.

Names, Occupations, and Addresses of Witnesses:
See “7 belowe

Photogra of objects, if availebles
i eT avalisble, however, the radar personnel attempted

taking photographs of the rader scopes with a 35 millimeter pasonal camera.
Apparently the exposure tine was not correct because no image was found on
the developed negative.

Obj ect Sighted:
for, uncountable, unexplained, and unknowm rader targets

which varied in intensity from light to heavy aircraft, traveling between

six (6) and sixty (60) miles per hour, heading Southwest at an altitude
of 2500 to 3000 feet.

Any other pertinent information:
pa en ormation is as follows:

DOWNGRADED AT 3
DECLASSIFIAD AFTRAT INTERVALS;

Ri2z2y
DQD DIR 6200. 10 BARS.

UNCLASSIFIED

1 cco FBI, Kno

1 co seamiey Division, AEC, Oak Ridge, Tenne 1 cc File
1 oc OSI, Knoxville, Tenn «

WD *n" 568 Se a se

—— ee

CODE FOR USE IN INDIVIDUAL PARAGRAPH EVALUATION
OF SOURCE: OF INFORMATION:

UNIDENTIFIED OBJECTS ON RADAR SCOPES wr emt wl en Me at CONFIRMED BY OTHER SOURCES . .

USUALLY RELIABLE. . . « «© s+

AT MoGHEE TYSON AIRPORT, KNOXVILLE, FAIRLY RELIABLE... . 6 «= POSSUBLY TRUE». , ss,

TENNESSEBe eee ee RP  @£&;»8 8BBMBITUELT URUE es ee 6 et 8

et a mM ee A, SE ET

hy 2 ee

SUMMARY OF INFORMATION

At 1766 hours on 29 November 1950, numerous unidentified paints (objocts)
appeared on the radar scopes of the 662nd AW Radar Detachment, located at MoGhee
Tyson Airport, Knoxville, Tennessee. These paints, so numerous that they almost
covered the “Restricted Area” at Oak Ridge, Tennessee, seemed to originate near
the conter of the "Restricted Area’ e" northwest boundary and travelled southeast
at about six (6G) miles per hour. As the paints crossed the "Restricted Arca"

(as indicated on the radar scope), some of them tended to change directions slightly
so as to travel cast-southeast. It appeared that these “paints” might be slightly
affected by the wind which was from the southwest at six(6) miles per hour. These
objects were estimated at 2500 ~- 100 feet mean sea level, md they could not be
sighted on the rader high scope until they were within ten (10) miles of the

Radar Station. From the original souree, the objects appeared to gain altitude

as they proceeded across the “restricted area". The maintenance personnel chs cked
the radar equipment in a fruitless attempt to find maifunctions, and the controller
switched the radar set from “high to low beam" etc., doing everything he could to
verify the readings, except to change the frequency cf the radar equipment. The
controller also called another radar expert to examine his findings and the above
information was verified by this persone The controllers describe their observa-
tions of the radar scope as "strengely cluttered with paints” as though pellets
from a shotgun shell were poured onto a table and allowed to go across it. (The
table being the “Restricted Area". )

The paints varied from 290 degrees to 330 degrees at from ten (10) to
twenty-six (26) miles distance from the Radar Station, end they would appear,
_ Gisappear, paint bright and paint dim at various times.

A fighter aircraft was sent to intercept one or any of the targets and was
veotored through, end around, specific targets end was vectored through, and
around, an area in which meny paints appeared, but no visual contact was reported
by either the pilot or the observer. Installation of Geiger counting equipment
into the fighter aircraft of the 6th AW Fighter Squadron was contemplated on
SO November 1950, at which time representatives from the NEPA Division, Oak Ridge,
Tennessee, inspected the aircraft for the possibility of said installations Most
of the targets were visable on the radar scope for two or three hours, and a few
could still be seen at 0500 on 3O November 1950.

The graph record of a background (Geiger) counter in the "Restricted Area"
indicated a pronounced rise in Alpha particles at 1900 hours on 29 November 1950,
and a alight rise in Gamma rays at the same time. These Alpha particles and
Gamma ray readings are wnaccounted for at the present time. Atomic Energy
Commission officials advise that there were no knom “Argon releases" (Argon

CISTRIBUTION % o@ Hq Third Army, Fort MoPherson, Gas 1 oo FBI, Knoxville, Tenn.
1 oo Seourity Division, AEC, Oak Ridge, Tennel oo File rs
90 OSI, Knoxy: omen 50s 1844.46

WDimsS6S soeromrmemse UNCLASSIFIED @itivi. a

—>

] ks

CODE FOR USE IN INDIVIDUAL PARAGRAPH EVALUATION

UNIDENTIFIED OBJECTS ON RADAR SCOPES OF SOURCE: OF INFORMATION:
COMPLETELY RELIABLE . 4... A CONFIRMED BY OTHER SOURCES . . 1
AT MeGHEB TYSON AIRPORT, KNOXVILLE, USUALLY RELIABLE. . . 6. b PROBABLYTRUE. 2... 4... 2

PAIRLY RELIABLE . . sw we c POSSIBLY TRUE . 2. 1. 1. wee 3

TENNESSEE.

iw 4 TRUTH CANNOT BE JUDGED... .

SUMMARY OF INFORMATION

charged with radioactive particles) during 29 and 30 November 1950,

On 30 November 1950, (during the presence of CIC and OSI representatives
from 1lllth CIC Detachment and Sth OSI District) at 1551 hours, a single unidentified
target appeared on the radar scopese Following is the controllers notes of the
objects progress.

vine (hours) Benge (miles) Azimuth Ceogroee Exon Radar
1354 17 | 20
1400 16 $00
1402 14 296
2.403 1s 290
1405 2 28 8
At this time the target disappeared from the scope

/

At approximately 16350 hours, on 30 November 1950, unaccountable paints
reappeared on the redar scopes and these generally followed a similar pattern,
as described beforee In addition to the regular radar crew, the following
| senda were present to witness these targets:

Lte Cole

e, Oak Ridge, Tenne
Oak Ridge, Tenne

Tr
Ms aaecicoeeiontet Oak Ridge, Tennessee
Ridge oratories, Oak Ridge, Tenn.
ak Ridge National Laboratories, Oak Ridge, Tenn.

OSI, Knoxville, Tennessee
CIC, Knoxville, Tennessee

These “paints” as before, were so numerous that they eould neither be counted nor
plotted and they remained visible on the rader screens until approximately 2550

or 2400 hours on 30 November 1950.
ili UNCLASSIFIED
Si

"

DISTRIBUTION B oo Hq. Third Army Fort MoPher son Ga 1 oo FBI, Knoxville, Tenn.
[3 Seour ity sary, Fort AEC, Oak Ridge, Tenn. 1 co File tne. .
. lox Vv, Se See

WD <3 568 —

30—63306-1 ENTRAR

ARY OF ee " Deeesber 1960

CODE FOR USE IN INDIVIDUAL PARAGRAPH EVALUATION

SUBJECT

UNIDENTIFIED OBJECTS ON RADAR SCOPES | °F Source: OF INFORMATION:
COMPLETELY RELIABLE . « . « « a CONFIRMED BY OTHER SOURCES . . 1
AT MoGHER TYSON AIRPORT, KNOXVILLE, | tsuuveume.....:: mom T

TENNESSE Mme 8 8 8} }©}©=©—h eee 8 6 2 be 6 eS = =6— We ek

*_ + © © ©  ;|- . SRP Wee CMW »« + «© se hlUmthlU

SUMMARY OF INFORMATION

fhe Weather Division at the Oak Ridge Atomic Energy Commission reports
the following concerning the weather during the above period:

Ban cate) «MBE Pn eh
210 é " furface 800 feet
280 12 1200 fees 2000 feet
240 14 2200 feet 3000 feet
260 28 S200 feet 4000 feet

The temperature at this time (1600 hours on 29 November 1950) was S2 degrees at
the surface; 30 degrees at 500: feet (1500 feet mean sea level), and 27 degrees

at 1000 feet (1800 feet mean sea level). There were no such adservations taken
on 30 Noverber 1950 but the temperature was listed as 45 degrees at 1550 hours.

The possibility that the Geiger counters in the “restricted area" are
receiving indications from the Oek Ridge National Laboratory plants is rejected
because at 6500 feet from the plants' “stack” there is only a 1/10th tolerance
of radioactivity (tolerance is the amount of radioactivity that a human body
can stand under contimuous exposure for ones entire life, without effecting the

_ persons health). Also rejected is the possibility that normal physiological
| padioactive masses, euch as radon (natural radioactivity radiated through the
ground from radium, eto., in the earth) could cause the Geiger counter readings
found in the “restricted area®, because said radon is a minute. concentration
generally measured at 1/1000th tolerance of that generated at 6500 feet from the
Atomio “stack".
7

Recent experiments designed to ascertain the effect of “Argon releases” on
rader have show that such releases cause no interference or any indication on
the radar screens at the Knoxville Radar Station. Prearrangemonts beiween ths
Rader Station and the Weather Division at Atomic Energy Commission, for the
release of Argon, were made and at the times of releases (one of which was a
full power release) there were no radar indications. Therefore, a previous
belief that such releases were being registered on the radar screens has been

disproven. ‘ °
UNCLASSIFIED
OISTRIEUTION S go Hq Third Army, Fort MoPherson, Ga. 1 co FBI, Knoxville, Tenne
1 eo File

1 00 Seourity Division, =, Oak Ridge, Tenne 5 1Lg44a6

WD rwUM 47 568 ws SOUEDeNt NE FOLNIOD 080168 vrei 1 Cease pas

Ji. oe

aunt a aa

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te nn eee

AF252.
ioe UNCLASSIFIED
PARTMENT OF T A
iGeomauenee enn Ute

wt)

THE INSPECTOR GENERAL USAF
Srx DISTRICT OFFICE OF SPECIAL INVESTIGA?
MAXWELL AIR FORCE BASE. ALABAMA

4 Doo uder 1950
4109

marrdm identified Fiying ubdjects

Tt Mr-oter of Social Invosticati ae
Hoodowertora, ve te Al Force
Vaubtngton 25, De Ge

le CTL (Prom 1715, (4 Sowenber until 2400 hours, % rovenbder
1950 unidentifio objects a» ecred at werivus tlven on the coo en of theo
AF Podar tothon, )noxville, l/ennessoe over the Controlled fron of vuk
Ridge, Ponessce.

Ze DT yp At 1715 hours, 23 Noverber 1950, throe (2) unidentifiod
mainte (objects) aoceored on tho redar eco-es of tha AP icdur stutd oy Cond
AGS Scuadron, Febhevetyeon Airoort, faotvwille, Tannoeree. “here painte ‘re
over the vak «dee Controlled ‘rea and they vere nob cireruft as they vove
moving at & exdcd of about aix wiles por houre Sy 1755 the sooves “hai boo
oon cluttered with mainte", Tuese objects ancenared to bivwo crifineted noo
the ground at the ceater of the northwest boundary of the Controllod 4ros
and wore traveling and asconding at a olow rate of ae oci ina wuthenetorly
direation over the Controlled Aroa. As the objects, nov at cn altitade of
2500 to KAH foot, ane over the center of the Controllod ‘res they are.
or fonned out and sone chanced directions to ‘ot south -uwet ent to “ect
Gonth oste “ho :aints voried from .% decress te S70 doross at from ton
(10) to twonty efx (26) milce from the iudar station and they vould an ear,
diss:s-our, »cin’ trisht and ~:int dim at various tince. An fe82 fL-htar
etten:ted intercootion of sxoscific tarrots tat no visusl or airvorne ralur
Contact wea radoe AG 19D tre wedints boron toe diainish cni after about vo
(2) houre had diga»peared from the scopes.

The following wind conditions prevailed over Gak Bids
at 1600, 29 hoverbor 19%: |

Turface wind ¥y 210 Dore § ash
140 ft. ba =O Pte 12 avh
30) ft. a uW Dore 14 och
» B00 [be ° - OO Det. «8 Goh J
(Vuk Kidge ie 600 ft. abows ssa level.)

A, ptf
| Als we

‘
i.

UNCLASSIFIED (,

pena

UNCLASSIFIED |

| A plee hoe boon arranced whoroby tho release of ratio
active o.rticles from the {nstellations at Unk “ddge will be checked for
mevsible readings on the raver u6o:0Ge

Cet ge 0 | PATIOK We HATS
$e 3.633 Lte Colonel, UAHA Lee
my District Commander |

TT Sa ee ee we =. eee .
e ,
uw ;

ee” HEADWARTLRS
Por Col Villis AIR WEATIER SZAVICE
131-71095 % . WBANTSR ANALYSIS DIVISION

ANDREWS AIR FORCE BASZ
WASHINGTON 25,Dc
i, December 1950

Weather Summary for Knoxville for the 28th, 29th, 30th November
28th

Mountains east of Knoxville obscured by low ceilings with snow and poor visibility.
Clear west of Knoxville.

Knoxville Weather. csesees

2000 overcast lowering to 1000 feet in snow showers and occasionally con-
tinuous snow becoming broken at 4000 feet at 2030E. One isolated snow shower
ceiling 3700 feet et 23302 but clearing again by 0030B, 29th.

29th

Front well east of Knoxville but still orographic clouds in mountains. Overcast
2000 to 3000 feet with snow over mountezins, 3-4 miles visibilities in mountains.

Knoxville Weather. ceeses
Scattered to broken 3000 feet, 5 miles in smoke becoming clear till 12305

becoming scattered 3000 till 14302 becoming scattered to broken at 25000 feet till
16302 becoming overcast to broken 25000 till 1930E becoming scattered to broken
till midnight. Visibilities 7 miles in afternoon. Scattered to broken over ridges
east, clear west of Knoxville latter half of day.

30th

Generally scattered to broken 10000 to 15000 becoming clear, Visibilities 10
miles,

WINDS ALOFT
28th
5000 —- 350/20k ies 10000 350/20K
5000 320/35k 10000 320/60-80k
5000 270/20k a, 10000 300/55k

Weather for Knoxville for the hours of 22302, 2330= on
12th, and for the hour of 00305 on the 13th Oct

122230E Clear 15 mi 173/52/0SE3 004 Runwy lets inopv N S$ ILS inopv
122330E Clear 15 mi 176/49/40SE2 O04 Runvwy lgts inopv N S ILS inopv
1300305 Clear 12 mi 180/48/40C 005 Runwy lgts inopv N S ILS inopv

See dy | pre ,
ROUTING AND RECORD SHEBINCLASS/Fj;-; Alt MATERIEL COMMAND

Iee thie form for inter-office correspondence Use authorized efice eymbels te designate Place Initiale of dictater and typist, telephone
within headquarters. addreseer and addresses. number and lecation te right of signatere.

Number all comments consecutively. ote warning signal at lower left of form. =
Use entire width of sheet, both sides. Remaining. seen aueteuen's a. Mh Beperate comments by horizontal lines across page.
sussect =€6Investigation of Radar Returns in the Oak Ridge Area.
to §«=—ss MC TA mom MCREEP}@4 DATE =. 1 JAN 195) COMMENT WO. =)
1. The attached ie submitted for inclusion with the trip report of Mr.
» Mre and Capt. » covering the trip to

Oak Ridge for the purpose of investigating unidentified radar targets and flying objeots
2. The report is for your information and distribution as you may desire.

M,

E. A. KIESSLING

Lt. Colonel, JCS/1s
Aoting Chief, Plans Office $-9258
1 Inol Electronic Subdivision B 126
Report Engineering Division 2 Rm 211
(4 oye) f ~% a
a
7 Leet - %
an -
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=
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—_
vw
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cst
—

Winds over Knoxville are not available.
for 12th and 13th Oct 1950:

1500Z 12 Oct
2000 Ft 350/20
1,000 350/33
6000 340/15
8000 340/48
10000 330/50

Following are winds aloft for Nashville

1500Z 13 Oct
60/02
350/09

* 360/11
360/11
340/11

Attached are RAOBS for Nashville for 1500Z on izth and 13th October 1950,

UNUSUAL RADAR RETURKS TH CES RCE AREA
BACKGROUND

eee ce

On the night of 29 and 30 November between the hours of 1700 and
2500 there were unugual returns or targets reported by the radar station

at the MoGee-Tyson Airport et Knoxville, Tennessee. This is the only
rader station in the area and is charged with the coverage of the Oak
Ridge Reservation. The only equipment operative on these nights was

a CPS-1. These targets caused considerable alarm to the personnel charged

with the security of the Oak Ridge plants and in particular to the per-
sonnel of the Air Foroe NEPA project. The weather on both nights was
clear and cold with light surface Windse An interceptor airoraft was
dispatched over the Oak Ridge Area but failed to intercept any targets.
The airoraft radar picked up no targets. Alerted ground observers on
the Oak Ridge Reservation neither sighted nor heard anythinge

There were conflicting versions of the mysterious targets as
observed on the radar scope. The two main versions were;

1. A few individual sharp targets appeared on the scope around
sundown in the sector from 60° through north to approximately
250°. The targets in the northern sector increased in number
and appeared to move south through a gap between two well
defined permanent echoes (ridge peaks) located north and north-
west of the Oak Ridge Reservation. As these targets moved
south over the reservation they fanned out and increased in
number until they completely blanked out or covered the scope
over the Oak Ridge Reservation. The apparent target speed
was 6 to 8 mph. The targets disappeared around 2500.

2. A wery few widely scattered targets appeared around sundown
in the north and west quadrants. A more noticeable one larger
than the others appeared in the northwest corner of the Oak
Ridge Reservation. Numerous targets appeared to "boil" out
of this one and spread over the entire reservation completely
saturating the scope in this area. This mass of targets spread

slowly to the south and southwest and disappeared south of 260°.

All targets disappeared around 23500.
DISCUSSION

Assuming no connections with previous reports of visual sightings,
mysterious characters in the hills and radar returns which were proven
to be flights of ducks, a solution is presented that the unusual rader
returns of the nights of 29 and 30 November were due to beam "trapping"
or "ducting" caused by the meteorological situation. . |

UNCLASSIFIED

—_—- -—— es

eet i i oe

DO DO are

UNCLASSIFIED

Both nights were clear and cold with maximum ground cooling to be
expected. The Weather Bureau Station at Oak Ridge has low level tempera~
ture records up to 1500 ft (Wiresonde) for a period of approximately one
year. The records indicate that on similar nights the inversions start
at the ground at sundown and reach a depth of 500-600 feet during the
night. There are no records for the nights of 29 and 30 Novembere Such
ground inversions are ideal for ducting which has the effect of increase

ing the number and intensity of permanent echoes and extending the ground
clutter. :

There are still the following questions to be answered in order to
differentiate these unusual sightings from others at different radar loca-
tions on similer nights: .

1. What are the “echoes” and why are they so sharp in outline?

2. Why do they appeer at sundown and disappear around 2300 local
time ?

3. Why do they have a movement of 6 to 8 mph?

4. Why are they concentrated in the Oak Ridge sector of the scope
and not in all sectors?

Suggested Answers:

1. The targets are thought to be high tension power lines, water
towers, smoke stacks and similar objects which will give a sharp
outline.

2. The radiative cooling starts at sundown and after a very shallow
inversion is formed the beam is bent or refracted just enough
to bring in the distant ground targets and as the inversion con-
tinues to increase in depth the beam is further bent so that the
number of targets increase in a direction closer and closer to
the station and at the optimum beam binding point the returns
become so numerous that it appears as a complete blank of the
scope and at this point we might say the ground clutter area
has been extended due to the "ducting." After 2300 the inversion
has became deep enough (400-500 ft) so that the bending of the
beam will be such that it will again pick up only distant targets.
If a close check is kept on the scope it is felt that the fade
out of targets will be similar to the fade in except in the
opposite sense, i.e., the ground clutter should break up into
numerous individual targets and then the individual targets
should disappear, a few at each antenna revolution.

S$. It is proposed that the reported movemént is only an apparent
movement caused by different targets being picked up by suces-
sive, relatively slow, revolutions of the radar antenna. This
would also explain the erratic direotions and speed of movement

of the targets. NCLASSIF IED
2

Ce

== SS ee ES eee ee ee

Se.

LASSIFIED

4. There are various versions of where the targets first
appeared, their movement and area of disappearance. It
is impossible to discount any of the versions as each
version is from personnel who actually observed the scope.
Only good scope photographs can give the true storye

A study of the general surrounding topographical features and the
radar scope picture shows that the strong "permanent echoes" (mountain
ranges) running in a continuous line from approximately 60° to 240° would
prevent any = targets being detected in the sector from 60° through
south to 240 Therefore, only ground targets in the sector from 60°
through north to 240° could be expected to be picked up during these strong
ground inversions or "ducting" conditions.

A more detailed study of the surrounding topographical features
reveal the following:

1) The city of Knoxville is located in the sector of 0-30° from
the radar station. The heat from the city would tend to counter=

act the grourd cooling and lessen the chances of ground "ducting"
in this direction.

2) The region adjacent to the radar site in the sector 270-0 (Oak
Ridge Sector) contains the Fort Loudown Reservoir. This sector
within a five-mile radius of the radar site is approximately
50% covered by the lake. An important parameter in the change
of index of refraction curve with height and time is the change
in moisture content. Considerable moisture is transported from
the lake surface to the very low layers of the adjacent air
during cold nights (steam fog conditions) and it is probable
that this effect greatly modifies the low level rader trans-
mission characteristics in this sector during clear, cold nights.
sete one atmospheric soundings adjacent to and over the lake

guired to determine the magnitude of this effect.

CONCLUSIONS :

1. The unusual radar returns in question are attributed to the
atmospheric conditions prevailing at the time of observation.

RECOMMENDATION:

1. Continuous scope photographs should be taken during unusual
radar return conditions.

2. Low level atmospheric soundings should be taken at 50 minute
intervals by the Oak Ridge Weather Bureau Station during these
unusual radar return conditions.

s UNCLASSIFIED

INCLASSIFIED

S$. Airborne sampling runs should be made adjacent to and through
the top of the inversion layer (approximately 500 feet at
2300 local time).

4. An L-Band search rader (TPS-1) should be obtained and used in
conjunction with the present S-Band set. Test runs have shown
that there is very little correlation with time between targets
picked up during ducting conditions on the two frequency bands.
Therefore, a comparison of the returns from the two radars will.
give an indication of whether the targets are due to "ducting."

& If possibdle, vr, Tes and the Weather Bureau personnel
at Oak Ridge should be brought to work on the problem on a

cooperative basis.
CL sawdZ-
Doge cver

Bt lRECT-F4¥

UNCLASSIFIED

HEADQUARTERS THIRD ARMY is

FORT McPHERSON, GEORGIA ys gh ae re.
UNCLASSIFIED /
AJACI=8 360.38 | 11 December 1950 “
SUBJECT: Unoonventional Airoraft !
TO: Commanding General
Hq 14th Air Force
Robins AFB, Macon, Georgia
ATTENTION: Director of Intelligence
Inclosed herewith is sunmary of information re unidentified
objects on radar scopes at McGhee Tyson Airport, Knoxville, Tennessee,
dated 1 December 1950,
FOR THE COMMANDING GENERAL:
p-
Colonel, GSC
AC of S, G-2
1 Inolt
‘As stated above DE
CIS 195F
Int 760 let Ind
Hq Fourteenth Air Force, Robins Air Force Base, Georgia.
TO: Commanding Generel, Air Materiel Command, Wright-Patterson AFB,
Dayton, Ohio, ATTN: MGIS : t ¢ ;
Forwarded in accordance with letter, Headquarters USAF, dated
8 Sept 50, subject: "Revorting of Information on Unconventional Aircraft."
o FOR THE COMMANDING GENERAL: )
DOWNGRADE) 4
D SSIFIED AFTER QNTERVALS;
‘ D DIR 6200.19 "8S
1 Incl UNCLASSIFIED =.)
n/c ,. a he Ve
LAL FF, — = 50S-294446
: aw22 ¥ he 3h
y
cm. ye

ro: 73

11 Decenber 1950

wee Gig ft \c

, CLASSIF IED PY: NoH.Rosonzarten

This informa tion io forwarded in accordance with ekroenent made in tele»hone con= -

versation between (ol ‘ndweios and Col Dunn on 6 lec 50.

vergonnel representing AYO Intelligence Dept and 'lectronics Sub-Mivision visited
Qak Ridge on § and 6 Dec. ‘‘atter was discussed with Vajor Steele, “ajor Carrs, and 'r.
Kurts, N#PA project, together with representatives of OSI and CIC in that dietrict.
Vatier was also discussed with “ajor Care and Capt eggger at Radar stition, knoxville,
| airport. The investirsators concluded that the targete whicr revortedly "blacked-out
the North ‘ast sector of the radar scope" were caused by groun! targete which becane
visible due to “anomalous proparation” or bending dowward of tie radar beams. ~~+niing
of radar teams is caused by non<unifor7ity of the atmosphere in either density or
moisture content. This phenanenon is sonetinces referred to aa “tenperature inversion"
or “duct" offect. The theory of how this effect occurs is too lencthy for further
discussion here. |

Important characteristics of the reported rader targeta, an stated by the raiar
operations officer, Cant CREM, ore given below:

le | Tirat tarrect a-peared in the northnest corner of the Fostricted aroa.
2. Additional targets appeared in the sate genoral area and spread south and east.
3. All targetea oppcared in a sector totween aporoximately 26) ani 350 derrees

and between the ranges of 12 and 25 milos.
L. Tarcote first appearcd at about 1/15 and wore seen until 233% on 29 Viov 5).
UNCLASSIFIED u mt 4

4 ae 2

a‘lstis Co, A'C

Wicks se BYt HR Rosengarten
UNCLASSiFiED DATE: 11 Dec 50

5s rarcets of tho save nature as those o served on the 29th appeared on the
30th of Noventer 1950 between tho hours of about 1639 = 233).

6.  Parvanent ect:oos, said to te a railroad track, in the area of the unknom
echoos were such more distinct during the period of observance of unknom targets.

7+  Oround clutter extended on the radar scope out to about 12 miles in the
direction of Sak fiidge, and high rountains, 3 t+ 1; miles outside of tho restricted

area t° the northenst were visible on the radar scroen.

$. Unknown targets first appeared on the lcwer radar been and as they + read
southward they were picked up by the upper bean.

9. Wind was from the southwest during the period of the observation of unknown

targets.
1). Targote were r-ported to te moving at a rate of 6 to & milos per hour. (It

is the investigators! belief that tho targets were so numorous that actual toverent of
a specific echo would be vary ard to ascertain. “iovevent could be mistaken by tho
@ppearance of new signal «choes as the affocted area spread. '

ll. Targets bevond tho so-callod "blacked-out area" were detected during the

perio? or reception of unknown target echoes.
12. #‘Intercept aircraft were unai le to intercept any of the unknown targets,
neither did any of these targets appear on the airborne redar set.

The sround radar eet, an AN/CP\~1 carly warning radar, opcrates at a frequency
of about 3900 megacycles per record, and , like all sicrowave electronic equipment,

UNCLASSIFIED

a