전쟁부(DOW)-미확인 이상 현상(UAP)-D100, 미확인 비행 물체에 대한 항공 물자 사령부 보고서, 1947-1948

This file is a collection of U.S. Government memoranda and correspondence relating to “Project Sign,” a 1948 U.S. Air Force program to investigate reports of high-performance airborne objects. The documents characterize some of these reports as being consistent with “real” objects rather than fabrications or resulting from perceptual errors. The U.S. Air Force cites the reported characteristics of the phenomena, e.g., high speed and maneuverability, as exceeding known performance envelopes of U.S. military aircraft and thereby presenting a potential national security threat, if validated. This potential threat prompted the Air Force to call on the Air Materiel Command (AMC), the Service’s Major Command for logistics and procurement from 1946 to 1961, to gather further evidence to assess the validity of the reports. The Air Force emphasized that there was an “imperative need” for such evidence to enable appropriate countermeasures. The stated urgency of this request reflects the strategic environment of the early Cold War, a period characterized by heightened national defense concerns amid rapid global advancements in aerospace design and development. In framing the call for an investigation, the Air Force noted that sustained public interest and persistent inquiries from the press may eventually require an official statement in response. AMC’s investigation found that observers were generally not mistaken when reporting that they had seen an airborne object, but that their characterizations of those objects as unusual was likely a reflection of the “limits of their personal experience.” It identified “a great many” of the objects reported with a rounded appearance as “weather or upper air scientific balloons of some type.” It also identified several cases in which the reported objects were most likely celestial phenomena, such as Venus. AMC found that a small number of reports lacked a “reasonable everyday explanation,” but that “so far, no physical evidence of the existence of the unidentified sightings has been obtained.” AMC expressly considered whether the phenomena may have been “vehicles from another planet,” but found no evidence supporting such an origin. Ultimately, AMC found that “there is as yet no conclusive proof that unidentified flying objects, other than those which are known to be balloons, are real aircraft.” In light of these findings, AMC recommended that the Department of War should avoid publicly commenting on the subject of “flying discs.” Responding to the Air Force’s anticipated concerns regarding public interest in the subject, AMC recommended that the Department should reply in terms that minimize the investigation’s inconclusive findings, focusing on positive determinations in cases assessed to be weather balloons and celestial phenomena.

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• Authority:
NND57563
S NOV
SUBJECT, Vlying Object Inoid•nta in the United Statea
!Os Cc=m.nding General. Air Materiel Command
Wright-Patteracc Air Force Bo.ee
Dayton. Chio
l. By lettcr'datcd 30 Decembor 1947 from the Director of
Research and Development,, Headqunrters USAF, your Ileadquartora
'/'I ~{)
:was required to eata.bli&h'"'ti:ojoct "SIGN",:_ ~
2. 'l'he oonclulion nppeo.ra ino11cep11ble that aa:io type of
flying object has been obecrved. I.dontification a.nd the origin
or these objects is not diaoernibl~ to this Headquarters. It ia
imperat1vo. therefore, that otforte to detennine whether theae
object• are or doiaoatic or fore1511 or1i1n must be increaaod until
oonolusive evidonoo 1c ,obtained. The needs or national defense
require euch evidence 1n order that appropriate countermeaaurea
cr,.y bo talc.on.
5. In addition to the imperative nood !'or evldenoe to perm1t
oountermasures, ia tho nooosoity ot in:l.'orcdnc the public as to
the ato.tus of t:he problem. To de.tc thorc hao boen too 1 ittlo do.ta
to present to the public. The pre••• however, h about to take it
into its own hands Md der.and to be told what wo do or do not know
about the e1tuntion. Silence on our part will not long bo ccoopt­
ablo.
4. Request imnediate information as to your conclusions to
date and your reoo=cendations a.a to tha information to be giTen
to the preea • Your recamnendat1 on is requestod ala o '18 to
whether thn.t infornation ahould be offered to tho press or with­
hold until it i s actively sought by the press.
BY COlWAlm CF THE CHIEF OP S1'.AFF1
Pl05530

8 NOV 1148
SUBJECT, Flying Objeot Incident• in the United State•
TO, Co ndin Gen ral, Air toriel Co
rieht•Patter•cn ir Foroo Be.a
D yton, Olio
~ J~ ~
<t
l. By letter dated 30 December 1947 tro the Director of
Research and Development, Headquartera USAF, your Headquart ra
•
waa required to eat bliah Project 'SIGN". - '
2. The conolu ion pp are ineaoapabl'e that e typo of
flying objeot baa been oba rved. Identifio :tion nd the origin
ot theae objects ia not discernible to this Headqu rtera. It ia
imperativo, therefore, that ei't'orta to determine wh ther these
objects are or om etic or foreign origin uat be increaa d until
conolu ive e ideno ie obtained. The need• or national defense
require auoh evidence 1n ordor that appropriate countermeaaurea
:y bo taken.
3. In addition to the imperative need for evidence to permit
counter aaur 1, ia t oeaaity of informing the public aa to
the stat • or the problem. To dat ther ha. be n too little data
to presen to th publio. The pres , awever, ia •bout o t ke it
illto its n hand and dei:and to be told •hat we do or do not know
on
bout th aituation. Silence our p rt will not long be accept­
able.
,. Request diate info tion aa to your concl udona to
date and your r co ondationa as to the infor tion to be iv n
to the pres. Your recommsndation is requested lao as to
whether that infor ation ahould be orrero to the pr 11 or with­
hel9 until it ii actively sought by the pr as.
BY CO OF THI CHI F OP STAFFi
! 11&?£
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;i.... ??,;C;~~·--~,,....__,
c. 1'. CABSL!a -
lajor Oe:oeral, USAI Oftloe of
t Intelligence,
Director o t Stat! OperatioDS
J)eputy (lbief a i) • ,
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DEPARTMENT OF THE AIR FORCE
HEADQUARTERS UNITED STATES AIR FORCE
WASHINGTON
S NOV 1948
SU ..,..,CT: Flylne; Object Incidents ir. the 'Jnitod Sio.tes
T01 Comnnndine; C nero.l ..Air Lo.tor.:.01 CoxilTltmd
,.riJ1t- a.1.t: rr.o;i ..ir l•orce Dace
Du. ton, C,hio
l , By letter dated 30 Jecember 1947 fro, the Dlrec~or of
oseEi.i·ch and !) ve o n:ont. Headquarters US F, Jour ;Ioad .ua.rter..
..as r 1uired to ostubl • s· Projoct "SIGN".
2. '!'\o cancl r..i.on n,pear:.. inaoc 1nl thut. ... oruo typo of
flyin..., ob~~ct he.s been obser,;ed. Itlonti..ricution and the ori..,in
ol' thetio objoctc .i.o not d'soorn·u1e to tr.is Head1uu.·ters . It is
inpcrntive, t orefore, t lf.d: efforts to dc,terr ·no, hcther t ese
oujacts o.r of' Jon.fJotic or f'orcie;n oril,in r.:..:ct be i.ncroa.aed until
cone uo·vo videnco i ... obt ined. 71e needs of national dofenso
ro 1uire ouch evidonco i."l order that appropr· to oounterneo.sures
no.y be io.l.en.
~- In udttl l:ion to th ir poro.+ivc nee.:i for evidence i.o oerruit
c:ount rrxnsures, is the. necossil.y o.. infor,.. · g L' e PU 1 •c us to
the statt1s of tho probl . To .:10.te ther ha.s been Loo 1itt o do.tu
to presort to tla .ublic . • he press, 'o. v01, io about to ta·o ·,
int., •to o,, h nds unu de .:i.nd to be iolu , ut uo tlo or do rot know
i..b ' ~ 1c. s~{.uo.tlon . Silence on ot,r re.rt ,.ill r o~ lon.., l.Je uccopt­
ul.Jl
V .
4 . ::rl 'l.t.L,odkte inform tion tl.u to . our Co:icl 1.Hl i .... , 0
dute ano. reoo .uen..iat;ions a.c to the in.1.crmution ~o 'Le ;·v 11
to the pre.,., . Your rooo,n:x:nd.at;i o ·::; reque::itod ulso as to
whet}-or t ut inforr::i.tior. s 1oul d 1 o of.'i'ered to the prer.s or vrH.h­
hel d tntll it .:.sac lvo1y svuchL b. tle pro..s .
BY COI~ i~ID CF TH CHIE.-' OF vT• •FF:
C. P. CABXLL
lfajor C..iuc- al, USU
Director of Intolligenoo. Ottice ot
Deputy Cbiet ot Sta.ft, OperatiODS
I



....
C-OVER 'SHEET
*
a. ' RECORD OF BASIC CORRESPONDENCE OR REQUEST
FROM: DATE:
TYPE:
SUMMARY:
SUSPENSE
DATE _________
ASGD BY ________
12935
DATE RECEIVED DIR/INT NO.
c. SPECIAL INSTRUCTIONS - REMARKS
DATE _________
NO.
(Use other side this sheet for additional remarks)
d. TO BR. TO TO DIV. TO TO DIR/ INT TO
DOWN UP DOWN UP DOWN UP
0 IP-PP
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0 IP-FL AFOIP ASST EXEC
OIP-SP
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0 IR-CO ASST EXEC
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OIR-DD
OIR-AA AFOIR
OIR-SR
EXECUTIVE
OIR-RC
OAI-OA
DIR/INT
OAI-DA
OAI-AE AFOA I
OAI-AF
OAI-SV
}
PERS
H & R
ADMIN
B & F
CABLE \
X
Action
C ordination
e. DATE REC'D BR f. DISPATCH FILE b)/):-.1
DISPATCHED BY ~ TO e.C--
ACTION~~ 'U
S I GN ED __:;a.1t,/4tl DATE DISPATCHED LL-ls.-•~£ 4r1 (...,
9-1748,AF

g. TO: SPECIAL INSTRUCTIONS - REMARKS (Continued)
DATE
NO.
'
h. TO: DATE ________
NQ. ---------

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Basic ltr fr-Hq USA.F, 3 Nov 48 to CG, AMC, "Flying Object Incidents in
the United States"
1st Ind MCIAT/ABD/amb
Hq AMC, Wright-Patterson Air Force Base, Dayton, Ohio. 8 Nov 48
c.,
TO, Chief of Staff, United States Air Force, Washington 25, D. ATTNs
AFOIR
1. In attempting to arrive at conclusions as to the mture of uniden­
tified .flying object incidents in the United States, this Command ha.a me.de
a study of approximately 180 such incidents. Data derived from initial re­
ports have been supplemented by.further information obtained from check
lists submitted by mail, from interrogations of other field agencies, and
by personal investigation by personnel of this Command in the case of in­
cidents that seem to indicate the possibility of obtaining particularly
significant information.
2. The objects described fall into the following general classifica­
tion groups, according to shape or physical configuration,
a. Flat disc of circular or approximately o:l.rcular shape.
b. Torpedo or cigar shaped aircraft, with no wings or fins visible
in flight.
c. Spherical or balloon shaped objects.
d. Balls of light with no apparent form attached.
3. Some of the objects sighted have definitely been identified, upon
further investigation, as weather or upper air scientific balloons of some
type. A. great many of the round or balloon shaped objects indicated in
paragraph 2c above are probably of the same nature, although in most cases,
definite confirmation of that fact has been impossible to obtain.
4. Some of the objects have been identified as beiilg astro-physical
in nature. For example, in daylight sightings, the planet Venus has been
reported as a round, silvery object at extremely high altitude. Action is
being taken to obtain the services of a prominent astro-physicist as a oon•
sultant, to study all of the incidents to determine l'lhether some can be
identified as meteors, planets or other manifestations of astral bodies.
s.
Arrangements for accomplishing a study of the psychological problans
involved in this project are being made in coordination with the Aero-Medical
Laboratory at this Headquarters. The possibility that some of the sightings
are halluoir:a tions, optical illusions or even deliberate hoaxes has been con-
., 1/cf
sidered. ~
\ t:. ... b
l Jo~-<..-'
2
:>.t
T-73017

'•
1st Itld
Basic ltr fr Hq USAF, 3 Nov 48 to CG, AMC, "Flying Object Incidents in
tne United States~
s.
Although explanation of many of the incidents can be obtained from
the investigations described abOV'e, there remains a certain number of re­
ports for which no reasonable everyday explanation is available. So far,
no physical evidence of 'the existence of the unidentified sightings has
been obtained. Prominent scientists, including Dr. Irving Langmuir of the
General Electric· Company, have been interviewed to determine whether they
could advance any reasonable explanation for characteristics exhibited by
the objects sighted. In an early interview, Dr. Langmuir indicated that
these incidents could be expl&ined, but insufficient data were available
at that time on which to base definite conclusions. It is planned to have
another interview with Dr. Langmuir in the near future to review all the
data now available, and it is hoped that he will be able to present some
opinion as to the nature of many of the unidentified objects, particularly
those described as "balls of light."
7 • All information that has been made available to this Headquarters
indicates that the discs, the cigar shaped objects, and the "balls of light"
are not of domestic origin. Engineering investigation indicates that disc
or wingless aircraft could support themselves in fli1?11t by aerodynamic means.
It is probable that the problems of stability and control could also be
solved for such aircraft. However, according to current aerodynamic theory
in this country, aircraft with such configurations would hl.ve relatively
poor climb, altitude and range characteristics with power plants now in
use.
a.
The possibility that the reported objects are vehicles from another
planet has not been ignored. However, tangible evidence to support con­
clusions about such a possibility are completely lacking. The occurrence
of inoidents ill relation to the approach to the earth of the planets Mercury,
Venus and Mars have been plotted. A periodic variation in the frequency of
incidents, which appears to have some relation to 'the planet approach curves,
is noted, but it may be purely a coincidence•
9. Reference is made to "The Books of Charles Fort" with an introduc­
tion. by Tiffany Thayer, published 1941, by Henry Holt & Co., New York, N. Y.
It appears that simular phenomena have been noted and reported for the past
century or more.
10. In view of the above, the following conclusions are drawn,
a. In the majority of cases reported, observers have actually
sighted son-, type of flying object which they cannot classify as en air­
craft within the limits of their personal experience.
T-73017

1st· Ind
Ba.sic ltr fr Hq USAF, 3 Nov 48 to CG, AMC, "Flying Object Incidents in
the United States"
b. There is as yet no conclusive proof that unidentified flying
objects, other than those which are known to be balloons, are real aircraft.
c. Although it is obvious that some types of flying objects have
been sighted, the exact nature of those objects cannot be established witil
physical evidence, such as that which would result from a crash, has been
obtained.
11. It is not considered advisable to present to the press information
on those objects which we cannot yet identify or about which we camiot pre­
sent any reasonable conclusions. In the event that they insist on som,
kind ot a statement, it is suggested that they be informed that m.a:cy ot
the objects sighted have been identified as weather balloons or astral
bodies, and that investigation is being pursued to determine reasonable
explanations tor the others.
12. A report, summarizing the results obtained from analysis of the
data and a technical investigation of the engineering aspects of -the objects
described, is nearly complete, and a copy will be forwarded to your Head­
quarters in the near future.
FOR mE COMMANDING GENERA.Ls
/f:; !!;:;
Colonel, USAF
•
Chief, Intelligence Department
T-73017

AFOIR-CO/Lt. Col. Garrett/ru./4544
S- y
12 Nov 48 )/k v'
D/L t R ll~I: , ZI Au 1..8, oubjt Projoat .,..,lGN''
~NOV 1 5 1948
Af'. ll,-C0-5 (L-10-78) 2nd lrut
c.
D pt. of tho Air cro , Hq U Af, sr.1fl5tcn 2,, D.
Tv: Co neral, 1:r utcriol Co. nd, r i ht- att. I\ en Ai:r
f<,Tcc :w , ,r1 ht 1 ld, l.tlio
rAX0-3
l . lotter•s re.tercnc t c.tJtactin~ cf
l.4t.1 witt, t.he rst uc rr.1n
<Jr had been e, b., Project el. o t d~cioicn
o a r ul.t or the cont ronco a > eadquartcrs 'r/ Jul,y l,46.
U6 a .forwarded re:t,y as b sibl v u in tab-
nt. o! a d1re0t. Np<;.rtiJ• ay t n• pilots•
..2. lt lo t.heretor :requested t .....t Project. ui1f1 pcr~o:_.i ol , ru--
rru nta to tinl1st. t.i e a rvicc o~ tt e Ur Troil J.,Ort Anoociatic.r.. 1n
order t.o devclo, ay1,t . er • U. -'• &1rl11 e pL.c.;to could" ;Qk~ t'l.ru.h
re,IQrt.s ut any w.uaual o rl l aightJ.n&°& <liract to your U adqua.rtcrs.
J. ln thi!l acnM·,cticn it.,ia ugg steJ thtit t o " 1h,nt.lal ae nt.
of Ir.fc::r..:~t.1on" inolosecl itt• lat. ln1..or cnt ) prcv tco d tailed for
pr ct1cal u... b.; airline pilot.a·.ln fon ard.inj u-dtir.il r liorto to our
J dcu rtera•
IY,
.BY Ci.I • D
ROBERT T ·''{ /)R 3rd
Colene c.•
• Chief , c. ..cc.tlo1. Branch
Air Intelligence Require::ients D1v1a10D
Directorate of Intelligence
Ref: Ltr fm Hq USAF, 27 Aug 48, subject as above . (Jlready in fil~)
1st Ind fm Hq AW, lCIAX0-3, 26 Oct 48, same subject.

AFOIR-CO/Lt .Col.Garrett/<br/4544
26 1948
7 AUG 1948
OBERT TAYLOR 3rd
olonel , USAF
Chi0f, Col 1 oGt i on Branch
Air I telligence Requirements Division
Directorate of Int lligeno~
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AMC
Subject: "Project 'Sing'"
1st Ind MCIAX0-3/RRS/~j
Hq AMC Wright-t'atterson Air Force Base, Dayton, Ohio, 26 Octo 48
TO: Chief of Staff, United States Air Force, WashingtLn 25, D C.
ATTN: AFOIR-C0-5
1. With reference to paragraph 1 above, the efforts to enlist
the cooperation' of Uni ed States airlines in reporting sightings of
unusual aerial phenomena directly to this Comm.and are greatly appre­
ciated.
2. This Headquarters further requests c0operation in effecting
distribution and use by commercial airlines of an "Essential Elements of
Information" check list, copies of wLich are inclosed. This·li13t may
be used as a supplement to the publication JANAP 146, developed by the
Joint Communications-Electronics Committee for the reporting of 11flying
disc" sightings .
FOR THE. CO NDING GENERAL:
/s/ W. E. Goll
for H. M. cCOY
1 Incl: Colonel, USAF
6 cys EEI form Chief, Intelligence Department