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Project Blue Book Special Report (second copy)

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This is Project Blue Book Special Report No. 14, "Analysis of Reports of Unidentified Aerial Objects," Project No. 10073, dated 5 May 1955. The study reduced about 4,000 sighting reports received by the U.S. Air Force between June 1947 and December 1952 to IBM punched cards and analyzed them statistically, including chi square tests comparing knowns with unknowns. It concludes that the reports very probably do not represent technological developments beyond present scientific knowledge, and it notes that no case produced physical evidence.

  • p. 3 …Sighting Reliability Groups for All Years and Each Year 25 Figure 10 Distribution of All Sightings…
  • p. 4 LIST OF ILLUSTRATIONS (Continued) Paiie Figure 14 Distribution of Object Sightings by Months Among the Eight…
  • p. 5 LIST OF ILLUSTRATIONS ' (Continued) Page Figure 38 Comparison of Evaluation of Object Sightings in the Strategic…
  • p. 7 …Evaluation of sighting reports, a crucial step in the preparation of the data for statistical, treatment…
  • p. 9 …Hynek1 s definition of the term is "any aerial phenomenon or sighting that remains unexplained to…
  • p. 10 …Although no evidence existed that unexplained reports of sightings constituted a physical threat to the security…
  • p. 11 records include condensations of all individual sighting reports, and the IBM cards used in vaTious phases…
  • p. 12 …Altogether, the data for this study consisted of approximately 4, 000 reports of sightings of unidentified…
  • p. 13 …Besides these dis- crete facts, an integrated written description of a sighting would be re- quired…
  • p. 14 …the maneuvers of the object or objects sighted. Prior to the start of the analytical study…
  • p. 15 …The num- ber of reports of sightings in a single folder varied from 1 to over…
  • p. 16 SINGLE OBSERVATION - A SIGHTING consisting of a single report from (1) one OBSERVER with no knowledge…
  • p. 17 …In brief review, ALL SIGHTINGS refer to all reports, UNIT SIGHTINGS refer to actual sightings, and…
  • p. 18 …The concept of a SIGHTING IDENTIFICATION NUMBER was evolved to fill this desire. Using one column…
  • p. 19 …About 800 reports of sightings were eliminated or rejected in this manner. Most of these reports…
  • p. 20 …Categories for INSUFFICIENT INFORMATION, PSYCHOLOGICAL MANIFESTATIONS, and UNKNOWN were provided for the sightings that could not…
  • p. 21 …During an identification conference, each sighting report was first studied, from the original data, by one…
  • p. 22 …in the future about a sighting or a group of sightings, and to provide answers, was…
  • p. 23 …ALL SIGHTINGS (all reports) UNIT SIGHTINGS, all observers UNIT SIGHTINGS, single observer UNIT SIGHTINGS, multiple observers…
  • p. 24 …of concen- tration of reports of OBJECT SIGHTINGS in an area. No other interpre- tation of…
  • p. 25 …sightings 2199 =100% All sightings 3201 = 100% Unit sightings 2554=100% FIGURE I FREQUENCY OF SIGHTINGS…
  • p. 26 Object sightings 2199=100% All sightings 3201 = 100% Unit sightings 2 5 5 4 = 1 0…
  • p. 27 …S I FIGURE 3 DISTRIBUTION OF OBJECT SIGHTINGS BY EVALU- ATION FOR ALL YEARS WITH COMPARISONS…
  • p. 28 …of object sightings 2(99 79 c <u a. 121 1501 Ilnsuf. — —info. All years 1947…
  • p. 29 …of object sightings 70 55 8 3 127 129 183 638 407 166 125 10,6…
  • p. 30 …3 0 FIGURE 6 DISTRIBUTION OF OBJECT SIGHTINGS BY CERTAIN AND DOUBTFUL EVALUATIONS FOR ALL YEARS…
  • p. 31 * • < * , ^ | j f c en Unknown object sightings J F M A M J J A S…
  • p. 32 …27 = 3.6% FIGURE 8 DISTRIBUTION OF OBJECT SIGHTINGS BY SIGHTING RELIABILITY GROUPS WITH EVALUATION DISTRIBUTIONS…
  • p. 33 …of object sightings 2199 79 43 186 169 121 Q. 40 30 20 10 0 1501…
  • p. 34 …Poor FIGURE 10 DISTRIBUTION OF ALL SIGHTINGS BY SIGHTING RELIABILITY GROUPS. SEGREGATED BY -__-_z MILITARY AND…
  • p. 35 …4 % FIGURE II DISTRIBUTION OF OBJECT SIGHTINGS BY REPORTED COLORS OF OBJECTCS) WITH EVALUATION DISTRIBUTION FOR…
  • p. 36 …info FIGURE 12 DISTRIBUTION OF OBJECT SIGHTINGS BY NUMBER OF OBJECTS SEEN PER SIGHTING WITH EVALUATION…
  • p. 37 …FIGURE 13 DISTRIBUTION OF OBJECT SIGHTINGS BY DURATION OF SIGHTING WITH EVALUATION DISTRIBUTION FOR EACH DURATION…
  • p. 38 …of object sightings 70 55 83 9 0 £ 8 0 JZ rou 0> § 6 0 v…
  • p. 39 …90 100 FIGURE 15 DISTRIBUTION OF OBJECT SIGHTINGS BY SHAPE OF OBJECTS) REPORTED WITH EVALUATION DISTRIBUTION…
  • p. 40 …40 50 60 Evaluation in Per Cent FIGURE 16 DISTRIBUTION OF OBJECT SIGHTINGS BY REPORTED SPEED…
  • p. 41 …of all sighting 3201 All yeors 117 205 164 306 160 2018 O Location not stated…
  • p. 42 …f FIGURE 18 COMPARISON OF KNOWN AND UNKNOWN OBJECT SIGHTINGS BY COLOR,1947-1952 A-7496
  • p. 43 …OBJECT SIGHTINGS BY NUMBER OF OBJECTS PER SIGHTING, 1947-1952 A-7497
  • p. 44 …L_ FIGURE 20 COMPARISON OF KNOWN AND UNKNOWN OBJECT SIGHTINGS BY SPEED, 1947-1952 \ ' A-749§
  • p. 45 …21 COMPARISON OF KNOWN AND UNKNOWN OBJECT SIGHTINGS BY DURATION , 1 9 4 7 - 1 9…
  • p. 46 …22 COMPARISON OF KNOWN AND UNKNOWN OBJECT SIGHTINGS BY SHAPE, 1 9 4 7 - 1 9…
  • p. 47 …23 COMPARISON OF KNOWN AND UNKNOWN OBJECT SIGHTINGS BY LIGHT BRIGHTNESS, 1947-1952 A-75 01
  • p. 48 …MONTHLY DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS ASTRONOMICAL VERSUS TOTAL OBJECT SIGHTINGS LESS ASTRONOMICAL A-7502
  • p. 49 …i i m FIGURE 25 COMPARISON OF MONTHLY DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS AIRCRAFT VERSUS…
  • p. 50 …MONTHLY DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS BALLOON VERSUS TOTAL OBJECT SIGHTINGS LESS BALLOON A-7S0…
  • p. 51 …DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS INSUFFICIENT INFORMATION VERSUS TOTAL OBJECT SIGHTINGS LESS INSUFFI- CIENT INFORMATION…
  • p. 52 …DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS I OTHER VERSUS TOTAL OBJECT SIGHTINGS LESS OTHER A-7506
  • p. 53 …MONTHLY DISTRIBUTION OF OBJECT SIGHTINGS EVALUATED AS UNKNOWN VERSUS TOTAL OBJECT SIGHTINGS LESS UNKNOWN A-7907
  • p. 54 Number of objects Color Speed Shape Duration FIGURE 30 CHARACTERISTICS PROFILES OF OBJECT SIGHTINGS BY TOTAL…
  • p. 55 …IN EACH SUBDIVISION THE TOP FIGURE INDICATES THE FREOUENCV OF ALL SIGHTINGS, THE MIDDLE FIGURE UNIT…
  • p. 56 oo FIGURE 32 DISTRIBUTION OF OBJECT SIGHTINGS BY EVALUATION FOR THE TWELVE REGIONAL AREAS OF THE…
  • p. 57 …16.2 % Balance of Central East Region 81 object sightings Netf/wrk/ 106 object sighting 61…
  • p. 58 O Dayton 144 object sighting! " 7 Balance of Central Midwest Region 164 object sightings FIGURE 34…
  • p. 59 …9 % Balance of Central Farwest Region 38 object sightings San Francisco 93 object sightings FIGURE 35…
  • p. 60 CJ1 ro o San Antonio 36 object sightings Balance of South Midwest Region FIGURE 36 COMPARISON…
  • p. 61 Ol 98 object sightings ""^-Albuquerque © Unknown 2 5 . 6 % Aircraft 20.8% Balloon 20.0% Unknown…
  • p. 62 II 5 Il/O FIGURE 3 8 COMPARISON OF EVALUATION OF OBJECT SIGHTINGS IN THE STRATEGIC…
  • p. 63 …Upon completion of these calculations, the cards representing OBJECT SIGHTINGS were sorted on the sign of…
  • p. 65 …50 25 -90 All object sightings Sun rise Unknown object, sightings Suniset -60 -30 + 30 +60…
For machine manipulation, it was desirable to be able to select the
sample of cards (all reports, all sightings, or all phenomena) to be in-
cluded in a particular study. The concept of a SIGHTING IDENTIFICATION
NUMBER was evolved to fill this desire. Using one column of the IBM
card, and the correlated working papers, the code for this function was
developed. Multiple punching elirninated the need to use several columns
for discrete expression of the variations., Selection of the proper number
in this column thus permitted selection of the desired sample of cards.
Evaluation of Individual Reports
of sighting reports was recognized as a crucial step in the
preparation of data for statistical treatment; inconsistent evaluations would
have invalidated any conclusions to be derived from this study. A method
of evaluation was, therefore, determined simultaneously with the develop-
ment of the questionnaire, the coding system, and the work sheet. It is
emphasized that all phases of evaluation, even including the tedious prep-
aration of the original data for statistical treatment, were entrusted only
to selected, specially qualified scientists and engineers.
Evaluation consisted of a standardized procedure to be followed for:
(1) the deduction of discrete facts, from data which depended on human im-
pressions rather than scientific measurements, (2) the rating of the ob-
server and his report as determined from available information, and (3) the
determination of the probable identification of the phenomenon observed.
Categories of identification, established upon the basis of previous experi-
ence, were as follows:
Balloon
Astronomical
Aircraft
Light phenomenon
Birds
Clouds, dust, etc.
Insufficient information
Psychological manifestations
Unknown
Other
The first step in evaluation, the deduction of discrete facts from
subjective data, required certain calculations based on the information
available in the sighting report. An example was the finding of the approxi-
mate angular velocity and acceleration of the object or objects sighted.
Care was taken during this phase of the work to insure against ^he deduc-
tion of discrete facts not warranted by the original data. Thus, even
though there was a complete lack of any valid evidence consisting of
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Cases discussed

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