Project Blue Book Special Report No. 14 (1955)

Project Blue Book Special Report No. 14, prepared for the U.S. Air Force’s Air Technical Intelligence Center (ATIC) by the Battelle Memorial Institute and dated May 5, 1955. It is the largest statistical study undertaken within the Air Force’s UFO investigations, analyzing approximately 4,000 sighting reports received between 1947 and 1952 and sorting each into evaluation categories — astronomical, aircraft, balloon, other, insufficient information, or unknown — across reliability groups.

According to the report, the data as a whole showed no marked patterns or trends, and an intensive study of the best “unknown” cases failed to yield even a rough model of a “flying saucer.” It concluded that the probability that any of the unknowns represented technology beyond present-day science was very small, and noted a complete lack of physical evidence in any case.

This archive reproduces a bounded slice of the report — the Summary, the Introduction, the two headline distribution figures, and the Conclusions — for reference; the original 309-page document is authoritative. The archive links the NARA collection page and an Internet Archive scan, and does not reproduce any agency seal or visual identity.

> NOTE: This is a **bounded slice** (11 pages) of the 309-page report — the Summary, the Introduction / Origin and Nature of Data, the two headline statistical figures (Figures 3 and 8), and the Conclusions. It is NOT the full document. The narrative pages and the figures were produced by Opus-vision OCR of rendered page images (figures transcribed as structured tables, with each reliability group's counts arithmetically cross-checked against the category totals); the Conclusions pages were reconstructed from the document's embedded text layer with programmatic correction of letter-spacing artifacts. Page markers show the report's printed page number (source PDF page in parentheses). The linked scan is the authoritative full document. <!-- p.vii (PDF p.7) --> SUMMARY Reports of unidentified aerial objects (popularly termed "flying saucers" or "flying discs") have been received by the U. S. Air Force since mid-1947 from many and diverse sources. Although there was no evidence that the unexplained reports of unidentified objects constituted a threat to the security of the U. S., the Air Force determined that all reports of unidentified aerial objects should be investigated and evaluated to determine if "flying saucers" represented technological developments not known to this country. In order to discover any pertinent trends or patterns inherent in the data, and to evaluate or explain any trends or patterns found, appropriate methods of reducing these data from reports of unidentified aerial objects to a form amenable to scientific appraisal were employed. In general, the original data upon which this study was based consisted of impressions and interpretations of apparently unexplainable events, and seldom contained reliable measurements of physical attributes. This subjectivity of the data presented a major limitation to the drawing of significant conclusions, but did not invalidate the application of scientific methods of study. The reports received by the U. S. Air Force on unidentified aerial objects were reduced to IBM punched-card abstracts of the data by means of logically developed forms and standardized analysis procedures. Evaluation of sighting reports, a crucial step in the preparation of the data for statistical treatment, consisted of an appraisal of the reports and the subsequent categorizing of the object or objects described in each report. A detailed description of this phase of the study stresses the careful attempt to maintain complete objectivity and consistency. Analysis of the refined and evaluated data derived from the original reports of sightings comprised (1) a systematic attempt to ferret out any distinguishing characteristics inherent in the data or any of their segments, (2) a concentrated study of any trends or patterns found, and (3) an attempt to determine the probability that any of the UNKNOWNS represent observations of a class, or classes, of "flying saucers". The first step in the analysis of the data revealed the existence of certain apparent similarities between cases of objects definitely identified and those not identified. Statistical methods of testing were applied which indicated a low probability that these apparent similarities were significant. An attempt to determine the probability that any of the UNKNOWNS represent observations of a class, or classes, of "flying saucers" necessitated a thorough re-examination and re-evaluation of cases of objects not originally identified; this led to the conclusion that the probability was very small, <!-- p.viii (PDF p.8) --> Therefore, on the basis of this evaluation of the information, it is considered to be highly improbable that reports of unidentified aerial objects examined in this study represent observations of technological developments outside of the range of present-day scientific knowledge. It is emphasized that there was a complete lack of any valid evidence consisting of physical matter in any case of a reported unidentified aerial object. <!-- p.1 (PDF p.9) --> INTRODUCTION In June, 1947, Kenneth Arnold, a Boise, Idaho, businessman and private pilot, publicly reported the now-famous sighting of a chainlike formation of disc-shaped objects near Mount Rainier, Washington. Resulting newspaper publicity of this incident caught the public interest, and, shortly thereafter, a rash of reports of unidentified aerial objects spawned the term "flying saucers". During the years since 1947, many reports of unidentified aerial objects have been received by the Air Force from many and diverse sources. The unfortunate term "flying saucer", or "flying disc", because of its widespread and indiscriminate use, requires definition. Many definitions have been offered, one of the best being that originated by Dr. J. Allen Hynek, of the Emerson McMillin Observatory of The Ohio State University, who has taken a scientific interest in the problem of unidentified aerial objects since 1949. Dr. Hynek's definition of the term is "any aerial phenomenon or sighting that remains unexplained to the viewer at least long enough for him to write a report about it"(1). Dr. Hynek, elaborating on his definition, says, "Each flying saucer, so defined, has associated with it a probable lifetime. It wanders in the field of public inspection like an electron in a field of ions, until 'captured' by an explanation which puts an end to its existence as a 'flying saucer'"(1). This definition would be applicable to any and all of the sightings which remained unidentified throughout this study. However, the term "flying saucers" shall be used hereafter in this report to mean a novel, airborne phenomenon, a manifestation that is not a part of or readily explainable by the fund of scientific knowledge known to be possessed by the Free World. This would include such items as natural phenomena that are not yet completely understood, psychological phenomena, or intruder aircraft of a type that may be possessed by some source in large enough numbers so that more than one independent mission may have been flown and reported. Thus, these phenomena are of the type which should have been observed and reported more than once. Since 1947, public interest in the subject of unidentified aerial objects fluctuated more or less within reasonable limits until the summer of 1952, when the frequency of reports of sightings reached a peak, possibly stimulated by several articles on the subject in leading popular magazines. Early in 1952, the Air Force's cumulative study and analysis of reported sightings indicated that the majority of reports could be accounted for as misinterpretations of known objects (such as meteors, balloons, or aircraft), a few as the result of mild hysteria, and a very few as the result of unfamiliar meteorological phenomena and light aberrations. However, (1) Hynek, J. A., "Unusual Aerial Phenomena", Journal of the Optical Society of America, 43 (4), pp 311-314, April, 1953. <!-- p.2 (PDF p.10) --> a significant number of fairly complete reports by reliable observers remained unexplained. Although no evidence existed that unexplained reports of sightings constituted a physical threat to the security of the U. S., in March, 1952, the Air Force decided that all reports of unidentified aerial objects should be investigated and evaluated to determine if "flying saucers" represented technological developments not known to this country. Originally, the problem involved the preparation and analysis of about 1,300 reports accumulated by the Air Force between 1947 and the end of March, 1952. During the course of the work, the number of reports submitted for analysis and evaluation more than tripled, the result of the unprecedented increase in observations during 1952. Accordingly, this study is based on a number of reports considered to be large enough for a preliminary statistical analysis, approximately 4,000 reports. This study was undertaken primarily to categorize the available reports of sightings and to determine the probability that any of the reports of unidentified aerial objects represented observations of "flying saucers". With full cognizance of the quality of the data available for study, yet with an awareness of the proportions this subject has assumed at times in the public mind, this work was undertaken with all the seriousness accorded to a straightforward scientific investigation. In order to establish the probability that any of the reports of unidentified aerial objects represented observations of "flying saucers", it was necessary to make an attempt to answer the question "What is a 'flying saucer'?". However, it must be emphasized that this was only incidental to the primary purpose of the study, the determination of the probability that any of the reports of unidentified aerial objects represented observations of "flying saucers", as defined on Page 1. The basic technique for this study consisted of reducing the available data to a form suitable for mechanical manipulation, a prerequisite for the application of preliminary statistical methods. The use of International Business Machine Corporation's systems was chosen as the best available mechanical equipment. The reduction of data contained in sighting reports into a form suitable for transfer to IBM punched cards was extremely difficult and time consuming. For this study a panel of consultants was formed, consisting of both experts within and outside ATIC. During the course of the work, guidance and advice were received from the panel. The professional experience available from the panel covered major scientific fields and numerous specialized fields. All records and working papers of this study have been carefully preserved in an orderly fashion suitable for ready reference. These <!-- p.3 (PDF p.11) --> records include condensations of all individual sighting reports, and the IBM cards used in various phases of the study. ORIGIN AND NATURE OF DATA Reports of sightings were received by the U. S. Air Force from a representative cross section of the population of the U. S., and varied widely in completeness and quality. Included were reports from reputable scientists, housewives, farmers, students, and technically trained members of the Armed Forces. Reports varied in length from a few sentences stating that a "flying saucer" had been sighted, to those containing thousands of words, including description, speculation, and advice on how to handle the "problem of the 'flying saucers'". Some reports were of high quality, conservative, and as complete as the observer could make them; a few originated from people confined to mental institutions. A critical examination of the reports revealed, however, that a high percentage of them was submitted by serious people, mystified by what they had seen and motivated by patriotic responsibility. Three principal sources of reports were noted in the preliminary review of the data. The bulk of the data arrived at ATIC through regular military channels, from June, 1947, until the middle of 1952. A second type of data consisted of letters reporting sightings sent by civilian observers directly to ATIC. Most of these direct communications were dated subsequent to April 30, 1952, and are believed to be the result of a suggestion by a popular magazine that future reports be directed to the Air Technical Intelligence Center. As could be expected, a large number of letters was received following this publicity. A third type of data was that contained in questionnaire forms completed by the observer himself. A questionnaire form, developed during the course of this study, was mailed by ATIC to a selected group of writers of direct letters with the request that the form be completed and returned. Approximately 1,000 responses were received by ATIC. In general, the data were subjective, consisting of qualified estimates of physical characteristics rather than of precise measurements. Furthermore, most of the reports were not reduced to written form immediately. The time between sighting and report varied from one day to several years. Both of these factors introduced an element of doubt concerning the validity of the original data, and increased its subjectivity. This was intensified by the recognized inability of the average individual to estimate speeds, distances, and sizes of objects in the air with any degree of accuracy. In spite of these limitations, methods of statistical analysis of such reports in sufficiently large groups are valid. The danger lies in the possibility of <!-- p.4 (PDF p.12) --> forgetting the subjectivity of the data at the time that conclusions are drawn from the analysis. It must be emphasized, again and again, that any conclusions contained in this report are based NOT on facts, but on what many observers thought and estimated the true facts to be. Altogether, the data for this study consisted of approximately 4,000 reports of sightings of unidentified aerial objects. The majority were received through military channels or in the form of observer-completed questionnaires; a few were accepted in the form of direct letters from unquestionably reliable sources. Sightings made between June, 1947, and December, 1952, were considered for this study. Sightings alleged to have occurred prior to 1947 were not considered, since they were not reported to official sources until after public interest in "flying saucers" had been stimulated by the popular press. REDUCTION OF DATA TO MECHANIZED COMPUTATION FORM As received by the Air Technical Intelligence Center, the sighting reports were not in a form suitable for even a quasi-scientific study. A preliminary review of the data indicated the need for standardized interrogation procedures and supplemental forms for the reduction of currently held and subsequently acquired data to a form amenable to scientific appraisal. The plan for reduction of the data to usable form consisted of a program of development comprising four major steps: (1) a systematic listing of the factors necessary to evaluate the observer and his report, and to identify the unknown object observed; (2) a standard scheme for the transfer of data to a mechanized computation system; (3) an orderly means of relating the original data to all subsequent forms; and (4) a consistent procedure for the identification of the phenomenon described by the original data. Questionnaire The first reports received by ATIC varied widely in completeness and quality. Air Force Letter 200-5(2) and Air Force Form 112(1) were attempts to fix responsibility for and improve the quality of the reports of sightings. To coordinate past efforts and to provide standardization for (1) A modified Air Force Form 112 lists pertinent questions to be answered in regard to an unidentified-object sighting. (2) Air Force Letter 200-5 places responsibility with the Air Force for the investigation, reporting, and analysis of unidentified aerial objects. This letter is dated 29 April 1952. <!-- p.16 (PDF p.24) --> Graphical Presentation Graphical representation of the important information contained in the tables is presented in Figures 1 through 38. These figures present the distributions of the important variables only by the total number of cases in each identification category, since no significant differences were found between the distributions of "Certain" and "Doubtful" identifications of objects with respect to the variables. A chronological study of these figures will afford a broad picture of the tabulated information, without the necessity of a detailed study of the tables. A critical examination of the figures will show that no trends, patterns, or correlations are to be found, with the exception of Figures 18 through 30. The apparent similarity of the distributions shown by these mirror graphs, Figures 18 through 23, was tested by statistical methods which showed that there was a low probability that the distributions of the KNOWNS and UNKNOWNS by these characteristics were the same. These tests and their interpretation are discussed in the following section. For purposes of this study, the strategic areas, shown in Figures 32 through 38, and Tables A213 through A240, Appendix A, were designated on the basis of concentration of reports of OBJECT SIGHTINGS in an area. No other interpretation of the tables or remaining charts was deemed necessary. Advanced Study of the Data It was recognized that the lack of any patterns or trends, as shown by the tabulations and graphs, provided an inaccurate basis for drawing definite conclusions. Accordingly, shortly before the sorting and tabulation program was concluded, a program of study of the data was developed to utilize statistical and other mathematical methods, which could lead to a more concrete interpretation of the problem. Position of the Sun Relative to the Observer The first thing that was done was to calculate the angle of elevation of the sun above the horizon and its bearing from true north as seen by the observer at the time of each sighting. With this information, it could then be determined whether there was a possibility that the reported object could have been illuminated by light from the sun. In addition, it could be determined whether an object could be a mock sun (sun dog) or whether there was a possibility of specular reflection from an aircraft at the position of the object, which would give the appearance of a "flying disc". A program of computation was set up and carried out to obtain the angle of elevation and the bearing of the sun for each sighting. All information needed for this calculation was available on the deck of IBM cards. <!-- p.19 (PDF p.27) --> FIGURE 3 — DISTRIBUTION OF OBJECT SIGHTINGS BY EVALUATION FOR ALL YEARS (structured transcription of the pie chart; total = 2199 sightings) | Evaluation | Count | Percent | |---|---|---| | Astronomical | 479 | 21.8% | | Aircraft | 474 | 21.5% | | Unknown | 434 | 19.7% | | Balloon | 339 | 15.4% | | Insufficient info. | 240 | 10.9% | | Other | 233 | 10.3% | <!-- p.24 (PDF p.32) --> FIGURE 8 — DISTRIBUTION OF OBJECT SIGHTINGS BY SIGHTING RELIABILITY GROUP, WITH EVALUATION DISTRIBUTION FOR EACH GROUP (structured transcription of the pie charts; total = 2199 = 100%) Reliability-group totals: Excellent 213 (9.7%); Good 757 (34.5%); Doubtful 794 (36.0%); Poor 435 (19.8%). Evaluation distribution within each reliability group (count = percent): | Evaluation | Excellent (213) | Good (757) | Doubtful (794) | Poor (435) | |---|---|---|---|---| | Unknown | 71 = 33.3% | 188 = 24.8% | 103 = 13.0% | 72 = 16.6% | | Astronomical | 52 = 24.4% | 174 = 23.0% | 154 = 19.4% | 99 = 22.8% | | Aircraft | 41 = 19.2% | 166 = 22.0% | 198 = 24.9% | 69 = 15.9% | | Balloon | 25 = 11.8% | 127 = 16.8% | 131 = 16.5% | 56 = 12.9% | | Insufficient info. | 9 = 4.2% | 27 = 3.6% | 111 = 14.0% | 93 = 21.4% | | Other | 15 = 7.0% | 75 = 9.9% | 97 = 12.2% | 46 = 10.6% | <!-- p.93 (PDF p.101) --> (12) Case XII. The object had windows in its top and front and its top midsection. It also had a set of propellers around its waist. It is not possible, therefore, to derive a verified model of a "flying saucer" from the data that have been gathered to date. This point is important enough to emphasize. Out of about 4, 000 people who said they saw a "flying saucer", sufficiently detailed descriptions were given in only 12 cases. Having culled the cream of the crop, it is still impossible to develop a picture of what a "flying saucer" is. In addition to this study of the good UNKNOWNS, an attempt was made to find groups of UNKNOWNS for which the observed characteristics were the same. No such groups were found. On the basis of this evidence, therefore, there is a low probability that any of the UNKNOWNS represent observations of a class of "flying saucers". It may be that some reports represent observations of not one but several classes of objects that might have been "flying saucers"; however, the lack of evidence to confirm even one class would seem to make this possibility remote. It is pointed out that some of the cases of KNOWNS, before identification, appeared fully as bizarre as any of the 12 cases of good UNKNOWNS, and, in fact, would have been placed in the class of good UNKNOWNS had it not been possible to establish their identity. This is, of course, contrary to the bulk of the publicity that has been given to this problem. The reason for the nature of this publicity was clearly brought out during the re-evaluation study. It is a definite fact that upon reading a few reports, the reader becomes convinced that "flying saucers" are real and are some form of sinister contrivance. This reaction is independent of the training of the reader or of his attitude toward the problem prior to the initial contact. It is unfortunate that practically all of the articles, books, and news stories dealing with the phenomenon of the "flying saucer" were written by men who were in this category, that is, men who had read only a few selected reports. This is accentuated by the fact that, as a rule, only the more lurid-sounding reports are cited in these publications. Were it not for this common psychological tendency to be captivated by the mysterious, it is possible that no problem of this nature would exist. The reaction, mentioned above, that after reading a few reports, the reader is convinced that "flying saucers" are real and are some form of sinister contrivance, is very misleading. As more and more of the reports are read, the feeling that "saucers" are real fades, and is replaced by a feeling of skepticism regarding their existence. The reader eventually reaches a point of saturation, after which the reports contain no new information at all and are no longer of any interest. This feeling of surfeit was universal among the personnel who worked on this project, and continually necessitated a conscious effort on their part to remain objective. 93 <!-- p.94 (PDF p.102) --> CONCLUSIONS It can never be absolutely proven that "flying saucers" do not exist. This would be true if the data obtained were to include complete scientific measurements of the attributes of each sighting, as well as complete and detailed descriptions of the objects sighted. It might be possible to demonstrate the existence of "flying saucers" with data of this type, IF they were to exist. Although the reports considered in this study usually did not contain scientific measurements of the attributes of each sighting, it was possible to establish certain valid conclusions by the application of statistical methods in the treatment of the data. Scientifically evaluated and arranged, the data as a whole did not show any marked patterns or trends. The inaccuracies inherent in this type of data, in addition to the incompleteness of a large proportion of the reports, may have obscured any patterns or trends that otherwise would have been evident. This absence of indicative relationships necessitated an exhaustive study of selected facets of the data in order to draw any valid conclusions. A critical examination of the distributions of the important characteristics of sightings, plus an intensive study of the sightings evaluated as UNKNOWN, led to the conclusion that a combination of factors, principally the reported maneuvers of the objects and the unavailability of supplemental data such as aircraft flight plans or balloon-launching records, resulted in the failure to identify as KNOWNS most of the reports of objects classified as UNKNOWNS. An intensive study, aimed at finding a verified example of a "flying saucer" or at deriving a verified model or models of "flying saucers" (as defined on Page 1), led to the conclusion that neither goal could be attained using the present data. It is emphasized that there was a complete lack of any valid evidence consisting of physical matter in any case of a reported unidentified aerial object. Thus, the probability that any of the UNKNOWNS considered in this study are "flying saucers" is concluded to be extremely small, since the most complete and reliable reports from the present data, when isolated and studied, conclusively failed to reveal even a rough model, and since the data as a whole failed to reveal any marked patterns or trends. Therefore, on the basis of this evaluation of the information, it is considered to be highly improbable that any of the reports of unidentified aerial objects examined in this study represent observations of technological developments outside the range of present-day scientific knowledge. 94