PROJECT BLUE BOOK

PROJECT 10073 RECORD CARD f

Se «|

12, CONCLUSIONS

% LOCATION

‘ 0D Was Balloon
16 Jon 51 | Oak Kidge Tena oO Probably Balloon
3. DATE-TIME GROUP TG. TYPE OF OBSERVATION QO Possibly Balioon
; O Wos Aircroft
‘To? pee he A~XGround- Vi sual © Ground-Radar O Probobly Aircroft
TT g 211,52 -_ 0 Air Visual 0 Air-intercept Redor | Possibly Aircraft
5. PHOTOS 6. SOURCE rr O Was Astronemical
C Yes 0 Probsbly Astronomical
ane Wothked Civilian (5) Megs ge
REE rg Sore oe Th SER OF OBJECTS | 9. COURSE ~ 1G Other__#F Insuff Daya
OS ee ee gt ts 0 po hd ent Dota for Evaluation
0 nknown
5 min one Hovered __
10. BRIEF SUMMARY OF SIGHTING Ti. COMMENTS

shape~ Light- Color = Uunsually Bright - Speed+ Observers in car moving NE. Object
Stationary. First thought to be A/C but was no} viewed throught right rear window.
moving. Plant authorityies checked but nothing| This is the only ximmaxiocix positional
was found to account for the sighting. data given. First magnitude star

Rigel low on horizon at 110 deg azimth
Planets Venus and Jupiter not visible
in East. No mention of disappearance

given with report. Insufficient Data
for evaluation,

See Case 21 Jan 51 = Same location)

ATIC FORM 329 (REV 26 SEP 52)

PROJECT 10073 RECORD CARD

1. DATE ( 2. LOCATION 12. CONCLUSIONS
0 Was Balloon
21 Jan 51 a , Oak Ridge, ron G Probably Balloon
3. DATE-TIME GROUP 4. TYPE OF OBSERVATION QO Possibly Balloon
—————— 1620 _ fe 5 O Ground-Vi sual 0D Ground-Redar Q Wos Aircraft
QO Probably Aircroft
GMT... 21/23202 = aes va tf Air-Wiéoeex Radar o Air-Intercept Radar O Possibly Aircraft
5. PHOTOS | 6. SOURCE at 0 Was Astronomical
O Yes QO Probgbly Astronomical
i No 0 Possibly Astronomical
7. LENGTH OF ODSERVATION 8. NUMBER OF OBJECTS | 9. COURSE hE Other Ground Target
! . = alana Dota far Evaluation
Three radar runs one Not given oe
10. BRIEF SUMMARY OF SIGHTING 11. COMMENTS - il
F-32 attempted to intercept an Explanation is"ducting",caused by the

unknown target. Three passes were made at inversion. Probable source being a gro: nid
the object but since it was over Oak Ridge target.

the pass could not be completed. Weather o
data indicates a double inversion existed
in the air.

ATIC FORM 329 (REV 26 SZP 52)

\ .
UliasS Lu bid rs “ coat
Of WPTNORTTY Crs
= Ay foe.
DUPACHM te 25 Jan 51 AS
22) "TGRTSR ALL a rein eh GAUUP DATE iT

Vol-hede oon \‘Emort
Sox 97, Alcoa, Tennessee

o of - - “Pr
a> el ually A951

on ee ., . A 2 ~~ ie ont = Ye 4A i on,
SUBJULT: Report on indicated airborne taryot over Os Didge Aroa.
te ars oon! .
"re : Knosvilte OSI Debachnams
i mo, = ‘“ AOL
. ~
f 7"

Jonuary 1751 sb 509 o'alock while on 4 practic
f tio Da52 airoraft the radar operator of cirer oS Gedy (2,
aN: 3c od on Sniicabion of ya
yongs of Ita yards, He notified the pilot,
cf sz who notified COL, GOT s2ve the fo ahead to incemert sare,
Te Tad Jar saat wes "loved on 69 tho tarot ard the mn bd 7 Atle rhe

,
.

*

fe
ents h ~ton on the "OC" sean (clovation) Indicated tha target was
sying altitude between tan end t- rontayeet ive decrees cbove the irtere
backing ain crafts altitude which was 7a fect, 46 4 rama of apprate
inately in yoris the indication cu clovaticn besen to descend unbil
tha linit of depression of bio cntenna was reached. 4s this po seat the

nilot cropred ito 2 noga down : Lt ioudes aml the tarcet was ax adn nicked’
up ad indicated the %+10 azea plant of Oak Ris fhe inl

olrersts thon broke of f tia intersent and roburned to Lenoir Cit;

Area shore it w:s to be "barsgot" for the otiwr alrers ide On the mext
rin in the area tie “barcot" wes ay tudiested cil 2 second run
male on same. Ab the completion of the flying period the redar
chserver roquested one mere rin over the area to again check for the
sone tyne indicatlon, She phlot ct: arted the rua frou apprexioately

aise “Ge 4:10 J MVoTven tng

70 miles and asain at 1 5 yaris the indication was xr celyed 2 nd locked ca
to, This tine ‘tha ron was co: wlsted to the Link’ of the antenna denresee

7 %

fon ond then broken of f because the Line of flint arain ws ceoros3 the
Ock IthLice Plant. This phenomena iias is sanorted to GOL and OSI.

.
CORPISIED Tis cory:
WEEE 9 UAT, Gb DOWNGRADED AT 3 OAR INTER

Knoxvills, Tonnesses DECLASSIFIED A aaa R i2 Vier
- LOD DIR 5260.10

VAT

WARS

Cesase {ONCCASSIFIED

; SUMMARY OF INFORMATION

PREPARING OFFICE
1itth CIC Tetachment, F.0 78, ?. 0. Fax Mnosvills, Temessea
SUBJECT CODE FOR USE IN INDIVIDUAL PARAGRAPH EVALUATION
OF SOURCE: OF INFORMATION:

_—- = ; amas ; COMPLETELY RELIABLE . 4... A CONFIRMED BY OTHER SOURCES . . 1
COU CTS SIGHTED OYSR CiAX RIDGE, USUALLY REUAWLE. © 2... B PROBABLYTRUE. 2... 1. 2
TOM SSZy FAIRLY REWABLE . . 2... . € POSSIBLYTRUE . 2. 2... 3

19Z . ‘ NOT USUALLY REWABLE . 2 ww D DOUBTFULLY TRUE. 2... wk, 4
(15 % 21 » Mary 1951) UMRELIASLE www tt E | 5
RELIABILITY UNKNOWN 2 2... F TRUTH CANNOT BEJUOGED . . . . 6
SUMMARY OF INFORMATION = =
(Refar S/I Subject as chova cuted 20 January 1951 pertaining to the sichting
ec 2345 hours on 16 January 1952)

At aporoximabaly 1645 hours on 16 January 1951, sn unusually brilliant
object was Sighted by. five persons criving in the "Control Zone” of the tonic
‘hergy Project, (ak Ridge, Termessee, Attached hereto is the ctabemant
eonesrning this phenamencn, The weather at the time of this sighbing is
cubstantially the same as reported in the pravious renor’ for 15 January
1951, a3 referred to above,

Records of the 663rd aC & Ve Squadron, (Radar), Molhee Ty30a Alrport,
Mnexville, Tennessee reveal that no direcralft were in the vicinity at the

At 1420 hours on 21 January 1951, a racar sighbing of on unicentifiod
ebject over Cak Ridge, Tomnessee was made by the airborne radars equipment”
installed in on F-i2 fighter uirerafth of the 5th av Fighter Squadron, 52nd
.i Pishter Group, “cGhse Tyson, airport, “noxville, Tonmnesses. This radar
interference vas reecived by the airborne radar as the airerars approached
the %10 Plant arca in the "Controlled Zone" of tie .tonic inercy Project,
Cak Ridge, Tonnessee, The fighter aircraft attanptad interceptions of this
tarest from various angles and found that the source of the interference
oninated from the area cf the X-i0 Plant. Uo visual reforence to anything
in the sky was reported Sy oclther the pilot or the radar cperator of the Pet2
aircraft. .

The weather at the bine of this incident is reportedly: “lartly clemdy,
with Hast winds at seven (7) miles per hour. Temerature 53 degrees, and
devpoint 19 dezyrees. ‘lo balloons or other weather apparatus vis in the
sky ab this time, Setween the hours 1545 and 1615, the wind vas variable
from south to northeast ab fran caim to eleven (12) Miles per hour.

ibbached herebo is a copy of the Letter outelsted by Sagmiiyme

Jub Lioutenant, U.S....%., concerning this phenomenon, CICII: The letter
"n® used in this letter denotes "thousand").
W2CE: 46 ~ © Radar Squadron, i'cGhee Ty30n s.ilzrpow, “noxville, Tenn,
Sth .W Righter Ocuadren, “noxcvilla, Tonn.
atomic “nerzy Commission \cabher bureau, 2% “idge, Tennessee,
, hea Five nersons listed on inclosure, Cuk Jldse, ornesses
de ) Os Office, Snoxcilia, Vonnessee DOWNGRADED AT 8 YEAR INTERVALS
Sy is DECLASSUMED AFTER 12 YEARS.
AA aN = Dov NiO Fa) 10
OLSTRIMUTION :
3 co @ Hq, Third amy, Ft McPherson, Ca lec- Gil, “neville, Senn
1 co = 2DL, Mnoxvyilla, Tonnessee 1. cc o File

WD in 568 oo pte at GSI Hesbes 5S ROARS

— 2S ——

| Se by
gNerassiFieD =f. gy
HEADQUARTERS THIRD ARMY

FORT MCPHERSON, GEORGIA

Offico of the Assistant Chief of Staff C2

9 FEB 190!

—_—

ATAGTH5 $60,585

SUBISC?:s Unconvon’%sional Aircralt

TOs Director of Intelligence
Fourteenth Air Forces
Robins Al¥38d, Macon, Georgia

Inclosed herewith is summary of information re objects sighted over
Oak Ridse, Tennassec.

| |
1 Incl: or HRY NM. ZELLIR |
S/I dtd 1 Fob 52 Colonel, GSC |

AG of S, G2

Int 350 1st Ind | |
Hy Fourteenth Air Force, Robins Air Force Base, Georgia.

TO: Coamanding General, Air Materiel Command, Wright-Patterson AF3,
Tayton, Ohio, ATIN: MGIS

Forwarded in accorjJance with letter, Headquarters USAT, & Sen SD,
subject: “Reporting of inforsation on unconventional aircraft,"

|
FR THE COMMANDING GENERAL: |

a 4. 3 YEAR INTER:
74 a\,. OM, no AT 8 YEN EARS.

= a —— aah TD
‘f/f — os PECLASS TN R 5200.10
{a tt TR EE |
C— WNCLASSIFIED = om it

"rns MNCCASSIEIED. oe

HEADQUARTERS dsdice
AIR MATERIEL COMMAND on hs

a, jn

COMMUNICATION. ANO™ tN- WRIGHT-PATTERSON AIR FORCE BASE j ON fs |
VELOPE TO COMMANDING ff

GINERAL, AIR MATERIEL DAYTON, OHIO j
COMMAND, ATTENTION FOL- o | i S ;
LOWING OFFICE SYMBOL: ; Looe

,

— MCTAXA HOTAYA-1a/JIIR/ns

SURJECT:; Unconventional Aircraft, ATI Project No. 10075 |

TOs Director of Intelligence
Headquarters, USAF
ATTN: Evaluation Division

Technical Capabilities Pranch
Washington 25, D.Ce

1. It is considered highly probable that the radar target detected
three times by the airborne radar set in the F-€2 aircraft on 21 January
was a ground target in the vicinity of the X-10 plent.

2. The peculiar phenomena of having the target first appear at an
altitude above the interceptor and then below the aircraft is considered
to be due to abnormal refraction of the radar electromagnetic emanations.
The airborne radar transmitted energy was refracted to the ground by a
ttemperature and/or moisture duct" that was located at about the same
altitude as the inierceptor; more details are given in paragraph 3 below.
When the interceptor closed on the target, the target first appeared to
be above the interceptor until the apex of the bent radar "trays" was
reached, and after that the target appeared below the interceptor.

3. A&A check with the local A’ base weather office indicates that

the Nashville weather station reported the following temperature data
for 2100 EST, 21 January 1951:

= Altitude Temperature Conditions
0 to 2000 ft No Change
2090 to 5000 ft Six degree increase
5000 to 000 ft Normal decrease in terp/increased altitude
%000 to 11000 ft Three degree increase
Above 11990 ft Normal decrease in tenmp/increased altitude
|
|
DOWNGRADED AT 3 YEAR INTERVALS;
DECLASSIFIED AFTER 12 YEARS, |

BOD DIR 6200.10

ee
ae =
<

—— EE - 51S~20241-¢
7

7-vya 7700 * ~ a
Hq AMC Form No, 9 (Rev 8 Fob 49) Al CLASSIEIE! Air Force-WPAFB-L-3 SEP 50 12700M

}

' ROUTING AND R .ORD-SHEET =

Use this form for Inter-office correspondence

within headquarters. addressor and addressee. number nnd tan to iat of signature,

Nomber a'! comments consecutively. Note warning signal at lower left of form. INITLALS: J els -Tibbert Haj . gUSAP
Remaining space ta sufficient only frp Ts: PAR oe: sree —

Une aathersed office symbols to designate proper spacing of typewritten si¢nature, oe * $ by horirental Lines across pouge.

suSECT Project 10073

Use authorized office aymbola ta designate AUTH: fiSs ints ie dictator and ‘typlet

NINGUASSISIES.

? ) |
| AR MATERIEL ys aati aas

telephone

—_——_— Se eo

FROM DATE] (| FEB ISS] Comment No. 4

7° MCTAXA-la MCTAXE
1, It is suggested that substantially the following be used in replying to the

attached letter, insofar as the report on the radar detected target is concerned:

[#3, It is considered highly probable that the radar target detected
three times by the airborne radar set in the F-S2 aireraft on 2] January
was a ground target in the vicinity of the X-10 plant.

42, The peculiar phenomena of heving the target first a-pear at an
altitude ahove the interceptor snd then below the aircra ‘t is considered to
te due to abnormal refraction of the racar electromagnetic emanstions, The
The airborne radar tranenitted energy was refracted to the vrounc by a
*tenperature and/or moisture duct" that wes located at shout the same altitude
as the interceptor; more details are given in paragraph 3 below, When the
interceptor c’osed on the target, the target first appeared to be above the
interceptor until the apex of the bent radar 'rays' was reached, and after
that the target appesred below the interceptor,

93. A check with the local /MCO base weather office indicates that the
Nashville weather station reported the foliowing temperature data for 2100 EST,
21 Jenuary 1951: ,

Altitude Temperature Conditions
0 to 2000 ft No change

2000 to 5000 ft
5000 to 80C0 ft
60C0 to 11.000 ft

Six degree increase

Normal decrease in tenp/increased altitude
Three cegree increase

Above 11000 ft Norms] Cecrease in temp/increased altitude

The norm2] atmosoheric temperature condition is that temper ture decreases
nearly linearily with increase in altitude, The sbove data incicates thet

two inversion Jsyers existed, one above the interceptor and one below, at
about the time the airborne radar target over the Oak Ricge ares was reported,
While complete and accur:te effects of temper ture inversion sre not thoroughly
uncerstood, it is considered that this effect caused the detection of s ground
tergetvo appear to be airborne, first above and then below the interceptor

as the interceptor cloged on the target. |

— () | cae
'
F Ditaala. fu
1 Tnel > JOHN E, LIBSER ‘Jones/ew
Cy Ltr, 2/7/51 fr Dir Spee Invest ‘Major, USAF 55170
Wy Ltr 52nd ¥AWG, v/o5/5) and Chief, Electronics Section B 2634
Rpt of Sighting Technicel Anslysis Livision P A=-1'7

=— _— = ee eee em ee ee eee eee ee ee

CNCRADED AT 3 YRAR INTERVALS;
51S— 20 GLASSINIED AFTER 12 YEARS.

ie >
en ae
a 4 SEDONA Ge-Ser STATE FE),

= t >: 3

Ny
ms ees es

tt ? - tt ee
> er

POD DUR 5200.10

—

UNCLASSI Fl

———_$_ ———

WF.L.31 OCT 49 4,652M
ANC Form Ma. 5 (Rev 29 Jul 47)

=

This form replaces AMC Form No, 10-3, which will
bo used unt! stocks on hand are exhausted,

ie =

crs =~ 5
‘ : P ( B on lg
4 : ; { fr » % “:
( we G2, RBG ep.
SS) er ace
1S. at. 20 tray 9
Ltr AC to TCR, Hqe, USAF," Unconventicnal Aircraft,~
ATI Project No. 10073

The normal atmospheric terperature condition is that temperature
decreases nearly linearily with increase in altitude. The above data |
indicates that two inversion layers existed, one above the interceptor and |
one below, at about the time the airborne radar target over the Oak Ridge
area was reported. While complete and accurate effects of temperature
inversion are not thoroughly understood, it is considered that this effect
caused the detection of a ground target to appear to be airborne, first

above and then below the interceptor as the interceptor closed on the
target.

lh. In view of the lack of factual evidence relative to the visual
sightings covered in the report, no positive explenation can be offered,
however, there are several possible explanations for this sighting.

FOR THE COMMANDING GENERAL:

BRUNOW W. FEILING

1 Incl Colonel, USAF
Cy Ltr 2-7-51 fr Dir Chief, Technical Analysis Division
Spec Invest w/incls Intelligence Department

DOWNGRADED AT 8 YEAR INTERVALS:
DECLASSIFIED AFTER 12 YEARS,
DOD Dik 5200.10

51S-20261-C

UNCLASSIFIED