Project Blue Book was the name given to the organized study of unidentified flying objects (UFOs) by the United States Air Force from March 1952 until it ended on December 17, 1969. Based at Wright-Patterson Air Force Base in Ohio, the project was first led by Captain Edward J. Ruppelt. It followed earlier projects, such as Project Sign (started in 1947) and Project Grudge (started in 1949). The goals of Project Blue Book were to find out if UFOs posed a risk to national security and to analyze UFO-related information scientifically.
Many UFO reports were collected, studied, and stored. Because of the Condon Report, which said that studying UFOs was unlikely to 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 were mistakes in identifying natural things like clouds or stars, or regular planes. The National Reconnaissance Office said some reports were from secret planes like the U-2 and A-12. 701 reports remained unexplained even after careful study. The UFO reports are stored and can be accessed through the Freedom of Information Act, but names and other personal details of witnesses have been removed.
Previous projects
Public USAF UFO studies began with Project Sign in 1947, after many well-known UFO sightings (see Kenneth Arnold). General Nathan F. Twining, who led the Air Force Materiel Command at Wright-Patterson Air Force Base, requested the project. 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 sightings. However, U.S. Air Force Captain Edward J. Ruppelt, who later led Project Blue Book, said that Project Sign’s first official report—called the Estimate of the Situation—written in late 1948, concluded that flying saucers were real, not made by the Soviet Union or the United States, and likely came from space. This idea was later rejected by General Hoyt Vandenberg, the U.S. Air Force Chief of Staff, because there was no physical proof. Vandenberg then ended Project Sign.
Project Sign was replaced by Project Grudge at the end of 1948. Project Grudge was criticized for focusing on proving that UFOs were not real. Ruppelt called this time the "dark ages" of early USAF UFO studies. Project Grudge concluded that most UFOs were natural events or misinterpretations. However, it also noted that 23 percent of the reports could not be explained.
Project Blue Book history
In 1951, several high-ranking United States Air Force generals were unhappy with how UFO investigations were being handled. They ended Project Grudge and started a new program called Project Blue Book in March 1952. General Charles P. Cabell was one of the leaders involved in this change. General William Garland joined Cabell’s team and believed UFOs deserved serious study because he had seen one himself.
The name "Project Blue Book" came from the blue booklets used for tests at some schools. Ruppelt, who led the project, said the name reflected how important the study of UFOs had become to the Air Force. The project was upgraded and became part of the Aerial Phenomenon Branch.
Ruppelt was the first leader of Project Blue Book. He had served in the Army Air Corps 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." He later wrote a book called The Report on Unidentified Flying Objects, which described the Air Force’s study of UFOs from 1947 to 1955. A scientist named Michael D. Swords said Ruppelt led the last serious effort to study UFOs.
Ruppelt made several changes to improve the investigation process. 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 complete a major study of all Air Force UFO cases in 1954, called "Project Blue Book Special Report No. 14."
Ruppelt avoided the problems that had affected earlier projects, such as Project Sign, where disagreements among staff slowed progress. He required his team to stay neutral and not favor any one theory about UFOs. He fired three staff members early in the project because they were too biased toward one idea. He also worked with scientists and shared regular updates with the public and military intelligence.
Each Air Force base had a Blue Book officer to collect UFO reports and send them to Ruppelt. During his time leading the project, Ruppelt and his team could interview any military personnel who saw UFOs without following the usual 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 near Washington, D.C. Ruppelt also set a trend of not seriously considering reports about UFOs landing or interacting with people, a practice later followed by other Blue Book investigations.
Astronomer J. Allen Hynek was the scientific advisor for the project. He had worked on earlier projects and helped create a system to classify UFO sightings, now known as "Close encounters." He started as a skeptic but later became more uncertain after reviewing some UFO reports he found hard to explain.
Ruppelt left Blue Book in February 1953 for a temporary assignment. When he returned, he found his team had shrunk from over ten people to just two. Frustrated, he suggested the Air Defense Command take over UFO investigations.
In July 1952, after many UFO sightings near Washington, D.C., the Central Intelligence Agency formed 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 data and concluded that most UFO reports had simple explanations and did not require further study.
In their final report, the panel said that unimportant UFO reports were causing problems for intelligence work and recommended the Air Force stop focusing on UFOs. They suggested using media, celebrities, and experts to explain UFOs as ordinary events and discourage public interest. They also warned that civilian UFO groups might influence public opinion and should be monitored.
Many researchers believe the Robertson Panel’s recommendations influenced how the Air Force studied UFOs for many years. Evidence shows these ideas were used at least two decades after the panel’s report.
In December 1953, a new regulation, Joint Army-Navy-Air Force Regulation 146, made it illegal for military personnel to share classified UFO reports with unauthorized people. Violators could face up to two years in prison or fines of up to $10,000.
In his book, Ruppelt wrote about how the Blue Book team became demoralized and lost their investigative responsibilities after the Robertson Panel’s recommendations.
As a direct result of the panel’s advice, the Air Force issued Regulation 200-2 in February 1953, requiring air base officers to only discuss solved UFO cases publicly and keep unsolved cases secret.
That same month, the newly formed 4602nd Air Intelligence Squadron (AISS) of the Air Defense Command began handling only the most important UFO cases.
USAF official statement on UFOs
The United States Air Force provided the following information about UFOs in USAF Fact Sheet 95-03:
From 1947 to 1969, the Air Force studied Unidentified Flying Objects as part of 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 were still 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 previous UFO studies and the Air Force’s experience with UFO reports from 1940 to 1969.
After these investigations and studies, the Air Force concluded that:
With the end of Project Blue Book, the Air Force canceled the rules that guided UFO investigations. All records from the project were moved permanently to the Modern Military Branch of the National Archives and Records Service, where they are available for public 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 organizations interested in aerial phenomena can be found in "Encyclopaedia of Associations," published by Gale Research. These groups help ensure that important UFO evidence is not ignored by scientists. People who see UFOs are encouraged to report them 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 using standard Air Force procedures. Bolender also wrote that reports about UFOs that might affect national security were not part of the Blue Book system. Details about other groups or agencies involved in these investigations are not known. At the time the memo was written, Bolender had recently finished a temporary assignment as Program Manager for Lunar Excursion Module Operations in the Apollo program, likely working under Samuel C. Phillips. Bolender remained in this role until he retired from the Air Force in 1972.
According to author Howard Blum, Freedom of Information Act requests show that the Air Force continued to track UFO sightings, especially a series of UFO encounters at U.S. military facilities with nuclear weapons from the late 1960s to the mid-1970s. Blum noted that some official documents describe these incidents in ways that reveal the fear felt by many Air Force personnel.
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 wanted their experts to help make the Air Force UFO study more scientific. The Battelle Institute created the standardized reporting form used to record UFO sightings. Starting in late March 1952, the Institute began analyzing existing sighting reports and entered about 30 report details onto IBM 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, which totaled about 3,200 by 1954, after Ruppelt had left Blue Book. Even today, this study remains the largest of its kind. Battelle employed four scientific analysts who divided cases into "knowns," "unknowns," and a third group called "insufficient information." They also classified "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 had evidence like radar or photographs. To classify a case as a "known," only two analysts needed to agree on a solution. However, to classify a case as an "unknown," all four analysts had to agree. This made the "unknown" category very strict.
Sightings were also divided into six characteristics: color, number, duration, brightness, shape, and speed. These characteristics were compared between "knowns" and "unknowns" to see if there was a meaningful difference.
The main results of the statistical analysis were:
(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 of the reports of unidentified objects represented observations of technology beyond current knowledge. Some researchers, including Bruce Maccabee, who reviewed the data, noted that the analysts' conclusions often disagreed with their own statistical results, which were shown in 240 charts, tables, graphs, and maps. Some believe the analysts may have struggled to accept their findings or may have written the conclusions to match the political climate in Blue Book after the Robertson Panel.
When the Air Force made Special Report #14 public in October 1955, it claimed the report proved UFOs did not exist. Critics pointed out that the report actually showed "unknowns" were clearly different from "knowns" at a very high level of statistical significance. The Air Force also incorrectly stated only 3% of the cases were unknowns, when the actual number was 22%. They claimed the remaining 3% would likely disappear with more complete data. Critics argued this ignored the fact that the analysts had already placed such cases into the "insufficient information" category, while both "knowns" and "unknowns" had enough information to make a determination. Additionally, "unknowns" often included higher-quality cases with better evidence and witnesses.
The findings of the Battelle study were later supported by a 1979 French GEPAN report, which said about a quarter of over 1,600 closely studied UFO cases remained unexplained, stating, "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, the head of SEPRA, found the evidence of extraterrestrial origins in these remaining cases so convincing that he wrote a book about it in 2005.
Criticism
Hynek was part of the Robertson Panel, a group that suggested UFOs should be explained away. Later, Hynek said that Air Force workers were uninterested, 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, "I found him to be honest and truly 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 overly boastful." Hynek claimed that Quintanilla ignored any evidence that did not support his own ideas. Hynek also described bitter arguments 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 violently at times), the probable."
Author and writer Robert Sheaffer stated that Project Blue Book collected 12,618 reports, and none of them 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 based on Project Blue Book, but it moved the investigation to the present day instead of the original 1950s-1960s time period.
The series followed two Air Force investigators: William Jordan played Major Jake Gatlin (who was replaced in the second season by Edward Winter as Major Ben Ryan), and Caskey Swaim played Staff Sergeant (later Technical Sergeant) Harry Fitz. The characters examined many different UFO incidents throughout the series.
A former officer from Project Blue Book worked as a technical advisor for the show. At the end of each episode, the following message appeared over the U.S. Air Force service mark: "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 had a major influence on the second season of the 1990–1991 television series Twin Peaks. Major Garland Briggs, an Air Force officer who worked on Project Blue Book, approached the main character, Dale Cooper, and told him that Cooper's name appeared in a strange radio transmission intercepted by the Air Force. The transmission came from the woods near the town of Twin Peaks. As the season continued, it was revealed that the source of the transmission was the Black Lodge, a realm where beings feed on human pain and suffering. It was also discovered that Briggs had worked with Cooper's rival, Windom Earle, on Project Blue Book, and that they had found evidence of the Lodge during their work.
Every episode of the original Battlestar Galactica spin-off series Galactica 1980 ended with a short message about the U.S. Air Force's 1969 Project Blue Book findings, which stated that UFOs are not proven to exist and "are not a threat to national security."
Project Blue Book inspired the drama series Project Blue Book, which began airing on the History Channel in January 2019.