Project Blue Book was the name used for the organized study of unidentified flying objects (UFOs) by the United States Air Force from March 1952 until its end on December 17, 1969. The project was located at Wright-Patterson Air Force Base in Ohio and was first led by Captain Edward J. Ruppelt. It continued work from earlier projects, such as Project Sign, started in 1947, and Project Grudge, started in 1949. The goals of Project Blue Book were to check if UFOs posed a danger to national security and to study UFO-related information scientifically.
Over 10,000 UFO reports were collected, examined, and stored. After the Condon Report, which found that studying UFOs probably would not lead to major scientific discoveries, and a review by the National Academy of Sciences, Project Blue Book ended in 1969. The Air Force summarizes its work as follows:
By the time Project Blue Book ended, it had collected 12,618 UFO reports. Most of these were mistakes in identifying natural things like clouds and stars or regular planes. According to the National Reconnaissance Office, some reports could be explained by secret planes like the U-2 and A-12. Seven hundred one reports were marked as unexplained, even after careful analysis. The UFO reports were stored and can be accessed through the Freedom of Information Act, but the names and other personal details of witnesses have been removed.
Previous projects
Public United States Air Force (USAF) studies of unidentified flying objects (UFOs) began in 1947 with Project Sign, after many well-known UFO sightings were reported (see Kenneth Arnold). Project Sign was started at the request of General Nathan F. Twining, who was the leader of the Air Force Materiel Command at Wright-Patterson Air Force Base. Wright-Patterson Air Force Base was also where Project Sign and all later official USAF UFO investigations were based.
Project Sign did not find a clear answer about the cause of the UFO sightings. However, U.S. Air Force Captain Edward J. Ruppelt, who later led Project Blue Book, stated that Project Sign’s first official report, written in late 1948, suggested that flying saucers were real objects, not made by the Soviet Union or the United States, and possibly from outer space. This idea was later rejected by General Hoyt Vandenberg, the head of the U.S. Air Force, because there was no physical evidence. Vandenberg then ended Project Sign.
In late 1948, Project Sign was replaced by Project Grudge, which was criticized for trying to disprove UFO sightings. Ruppelt called the time of Project Grudge a "dark age" for early USAF UFO studies. Project Grudge concluded that all UFOs were natural events or misinterpretations, though it also noted that 23 percent of the reports could not be explained.
Project Blue Book history
According to Captain Edward J. Ruppelt, by the end of 1951, several high-ranking and influential USAF generals were unhappy with how the Air Force was investigating UFOs. They ended Project Grudge and started Project Blue Book in March 1952. One of these generals was Gen. Charles P. Cabell. Another change happened when General William Garland joined Cabell’s team. Garland believed the UFO question needed serious study because he had seen a UFO.
The name "Project Blue Book" was chosen because it reminded people of the blue booklets used for tests at colleges and universities. Ruppelt said the name was inspired by how seriously high-ranking officers treated the project, as if studying UFOs was as important as a final exam. Project Blue Book had a higher status than Project Grudge, with the creation of the Aerial Phenomenon Branch.
Ruppelt was the first leader of the project. He had experience as a military pilot during World War II and later earned a degree in aeronautics. He introduced the term "Unidentified Flying Object" to replace older terms like "flying saucer." Ruppelt believed this term was more neutral and accurate. He later left the Air Force and wrote a book about the study of UFOs from 1947 to 1955. Scientist Michael D. Swords said Ruppelt led the last real effort to study UFOs.
Ruppelt made several changes to improve the project. He simplified how UFO reports were shared with military officials to reduce the stigma faced by witnesses. He also created a standard questionnaire for UFO witnesses to collect data that could be analyzed statistically. He hired the Battelle Memorial Institute to design the questionnaire and organize the data. Battelle used this information to study all Air Force UFO cases, completing a report in 1954 called "Project Blue Book Special Report No. 14."
Ruppelt avoided the problems that had affected Project Sign, where disagreements among staff slowed progress. He ensured his team did not take sides in debates about whether UFOs were of extraterrestrial origin. If staff members became too biased, they were removed from the project. Ruppelt worked with scientists and shared regular press releases and classified reports with the military.
Each Air Force base had a Blue Book officer to collect UFO reports and send them to Ruppelt. During most of his time leading the project, Ruppelt and his team could interview any military personnel who had seen UFOs without following the chain of command. This showed how seriously the Air Force took the investigation.
Under Ruppelt’s leadership, Blue Book studied famous UFO cases, such as the Lubbock Lights and a 1952 UFO sighting over Washington, D.C. Ruppelt also started a trend of not seriously considering reports of UFO landings or contact with supposed aliens, a practice later followed by Blue Book investigations.
Astronomer J. Allen Hynek was the scientific advisor for the project. He had worked on earlier projects and created the system of classifications for UFO encounters, now known as "Close encounters." Hynek began as a skeptic but later became more unsure about some UFO reports.
Ruppelt left Blue Book in February 1953 for a temporary assignment. When he returned, his team had shrunk from more than ten people to just two. Frustrated, he suggested that the Air Defense Command take over UFO investigations.
In July 1952, after many UFO sightings, radar and visual reports were recorded near Washington, D.C. These sightings led the CIA to form a group of scientists, called the Robertson Panel, to study UFOs. The panel included physicist H. P. Robertson and others. They reviewed six years of UFO data and concluded most reports had simple explanations. They recommended the Air Force stop focusing on UFOs and instead work to reduce public interest by using media and experts to explain UFOs as ordinary events. They also warned that civilian UFO groups might influence public opinion and should be monitored.
In December 1953, a regulation was created that made it illegal for military personnel to discuss classified UFO reports with unauthorized people. Violators could face up to two years in prison or fines of $10,000.
Ruppelt wrote in his book that the Blue Book team felt discouraged after the Robertson Panel’s recommendations. Soon after, the Air Force issued a rule in February 1953 requiring officers to only discuss solved UFO cases publicly and keep unsolved cases secret.
That same month, the 4602nd Air Intelligence Squadron was formed to handle only the most important UFO cases.
USAF official statement on UFOs
The United States Air Force has provided an official statement about UFOs, as detailed in USAF Fact Sheet 95-03:
From 1947 to 1969, the Air Force studied Unidentified Flying Objects through a program called Project Blue Book. This program was based at Wright-Patterson Air Force Base in Ohio and ended on December 17, 1969. Out of 12,618 UFO sightings reported to Project Blue Book, 701 remained unexplained.
The Air Force decided to stop investigating UFOs after reviewing a report from the University of Colorado titled Scientific Study of Unidentified Flying Objects. This report was also reviewed by the National Academy of Sciences. The decision was also influenced by earlier UFO studies and the Air Force’s experience with UFO reports from 1940 to 1969.
Based on these investigations and studies, Project Blue Book concluded that:
After Project Blue Book ended, the Air Force no longer followed rules for investigating UFOs. All records from the program were moved permanently to the Modern Military Branch of the National Archives and Records Service. These records are available for the public to review.
Since Project Blue Book ended, the Air Force has not found any new reasons to restart UFO investigations.
Several universities and scientific groups have studied UFOs during meetings and seminars. A list of private organizations interested in aerial phenomena can be found in Encyclopaedia of Associations, published by Gale Research. These groups help ensure that important evidence about UFOs is not missed by scientists. People who see UFOs are encouraged to report the sightings to local law enforcement.
An Air Force memo, released through the Freedom of Information Act on October 20, 1969, and signed by Brigadier General Carroll H. "Rip" Bolender, stated that even after Project Blue Book ended, UFO reports would still be handled through standard Air Force procedures. Bolender also wrote that reports about unidentified flying objects that might affect national security were not part of the Blue Book system. Details about other groups or agencies that handled these reports, or Bolender’s role in them, are not known. At the time of the memo, Bolender had recently completed a temporary assignment as manager for the Lunar Excursion Module in the Apollo program, likely working under Samuel C. Phillips. He continued in this role until he retired from the Air Force in 1972.
Author Howard Blum reported that Freedom of Information Act requests show the Air Force continued to track UFO sightings, especially a series of encounters from the late 1960s to the mid-1970s at U.S. military facilities with nuclear weapons. Blum noted that some official documents described the fear felt by many Air Force personnel during these incidents.
Project Blue Book Special Report No. 14
In late December 1951, Ruppelt met with members of the Battelle Memorial Institute, a research group based in Columbus, Ohio. Ruppelt asked their experts to help make the Air Force’s UFO study more scientific. The Battelle Institute created the standardized reporting form used to collect information about UFO sightings. Starting in late March 1952, the Institute began analyzing existing sighting reports and entered about 30 report details onto IBM punched cards for computer analysis.
Project Blue Book Special Report No. 14 was a large statistical study of all Blue Book cases up to that time, totaling about 3,200 by 1954, after Ruppelt had left the project. Even today, this study remains the largest of its kind. Battelle used four scientific analysts to classify cases into three groups: "knowns," "unknowns," and "insufficient information." The analysts also divided "knowns" and "unknowns" into four quality levels, from excellent to poor. For example, cases labeled "excellent" often involved experienced witnesses, such as pilots or military personnel, and included supporting evidence like radar or photographs.
To classify a case as a "known," only two analysts needed to agree on a solution. However, to label a case as an "unknown," all four analysts had to agree. This made the "unknown" category very strict.
Sightings were also analyzed based on six characteristics: color, number, duration, brightness, shape, and speed. These features were compared between "knowns" and "unknowns" to determine if there were important differences.
The main results of the study showed:
(More detailed statistics can be found in Identification studies of UFOs.)
Despite this, the Battelle Institute’s final report stated it was "highly improbable" that any UFO reports described objects from technology beyond current knowledge. Some researchers, like Bruce Maccabee, who reviewed the data, noted that the analysts’ conclusions often disagreed with the statistical results shown in 240 charts, tables, graphs, and maps. Some suggest the analysts may have struggled to accept their own findings or adjusted their conclusions to fit the political environment in Blue Book after the Robertson Panel.
When the Air Force released Special Report #14 in October 1955, it claimed the report proved UFOs did not exist. Critics argue the report actually showed that "unknowns" were clearly different from "knowns" at a high statistical level. The Air Force also incorrectly stated only 3% of cases were unknowns, while the actual number was 22%. They claimed the remaining 3% might disappear with more data, but critics pointed out that these cases were already placed in the "insufficient information" group. Both "knowns" and "unknowns" had enough information for analysis, and "unknowns" often included higher-quality reports with better evidence.
The findings of the Battelle study were later supported by a 1979 French GEPAN report, which found that about a quarter of over 1,600 closely studied UFO cases remained unexplained. The report stated, "These cases … pose a real question." When GEPAN’s successor, SEPRA, closed in 2004, 5,800 cases had been analyzed, and the percentage of unexplained cases dropped to about 14%. Jean-Jacques Velasco, head of SEPRA, believed the remaining unknowns provided strong evidence of extraterrestrial origins and wrote a book about it in 2005.
Criticism
Hynek was part of the Robertson Panel, which suggested that UFOs needed to be disproven. A few years later, Hynek said that Air Force workers were not interested, not skilled, and did poor-quality research. Hynek mentioned that people who criticized Blue Book called it "The Society for the Explanation of the Uninvestigated." About Ruppelt, Hynek wrote, "In my time working with him, I found him to be honest and confused about the whole UFO phenomenon." Regarding Friend, Hynek said, "Of all the officers I worked with in Blue Book, Colonel Friend earned my respect and acted with dignity, unlike some other Blue Book leaders who were showy or boastful." Hynek said Quintanilla ignored any evidence that did not support his idea. Hynek also described his disagreements with Moody, calling Moody "the master of the possible: possible balloon, possible aircraft, possible birds, which then became, by his own hand (and I argued with him strongly at times), the probable."
Author and writer Robert Sheaffer stated that Project Blue Book collected 12,618 reports, but none were important or helped increase knowledge about any subject, even after more than 50 years of study.
Project Blue Book in fiction
Jack Webb created and narrated Project U.F.O., a television series that aired in 1978 and 1979. The show was inspired by Project Blue Book, but it updated the story to take place in the present day instead of the 1950s and 1960s.
The series followed two U.S. Air Force investigators: William Jordan played Major Jake Gatlin, who was later replaced by Edward Winter as Major Ben Ryan in the second season. Caskey Swaim portrayed Staff Sergeant (later Technical Sergeant) Harry Fitz. The characters investigated many different UFO sightings.
A former officer from Project Blue Book worked as a technical advisor for the series. At the end of each episode, a statement appeared on screen over the U.S. Air Force logo: "The United States Air Force, after twenty-two years of investigations, concluded that none of the unidentified flying objects reported and evaluated posed a threat to our national security."
Project Blue Book influenced the 1990–1991 television series Twin Peaks. In the second season, Major Garland Briggs, an Air Force officer who worked on Project Blue Book, told the main character, Dale Cooper, that Cooper’s name appeared in a strange radio message intercepted by the Air Force. The message came from the woods near Twin Peaks. Later in the season, it was revealed that the message originated from the Black Lodge, a mysterious realm where beings feed on human pain and suffering. It was also shown that Briggs had worked with Dale Cooper’s rival, FBI agent Windom Earle, on Project Blue Book, and that they had discovered evidence of the Black Lodge during their work.
Each episode of the Battlestar Galactica spin-off Galactica 1980 ended with a brief statement about the U.S. Air Force’s 1969 Project Blue Book findings. The statement said that UFOs were not proven to exist and "are not a threat to national security."
Project Blue Book inspired a drama series with the same name, which began airing on the History Channel in January 2019.