Estimate of the Situation The Estimate of the Situation was a document supposedly written in 1948 by the personnel of United States Air Force ' s Project Sign - including the project ' s director , Captain Robert R . Sneider - which explained their reasons for concluding that the extraterrestrial hypothesis was the best explanation for unidentified flying object s . As late as 1960 , USAF personnel claimed that the document never existed . However , several Air Force officers , and one consultant , describe the report as being a real document that was suppressed . Jenny Randles and Peter Hough describe the " Estimate " as the " Holy Grail of ufology " and note that Freedom of Information Act requests for the document have been fruitless . Background . Project Sign was established in late 1947 , and was charged with investigating " flying saucer " reports . In line with orders from high - ranking USAF officers , Sign ' s personnel operated on the principle that the subject should be taken seriously , on the grounds that UFOs may represent genuine aircraft whose origins are mysterious and possibly threatening to US security . Chiles - Whitted Encounter . Though Sign investigated earlier UFO reports , Historian David M . Jacobs writes that the highly publicized Chiles - Whitted UFO Encounter of July 24 , 1948 " had a great impact at Sign " . In that encounter , two experienced airline pilots claimed a torpedo - shaped object nearly collided with their commercial airplane . Sign personnel judged the report convincing and compelling , partly because the alleged object also closely matched the description of an independent sighting from The Hague a few days earlier . According to Michael D . Swords , Sign personnel " intensely investigated " the Chiles - Whitted sighting for several months . Despite the lack of physical evidence , some Sign personnel judged this and other UFO reports quite persuasive , and concluded that UFOs could have only a non - earthly source . Swords writes , Given that there was no evidence that either the U . S . or the U . S . S . R . had anything remotely like the UFOs reported , Sign personnel gradually began considering extraterrestrial origins for the objects . Swords argues that this consideration of non - earthly origin was " not as incredible in intelligence circles as one might think . " Because many in the military were " pilots , engineers and technical people " they had a " ' can do ' attitude " and tended to regard unavailable technologies not as impossibilities , but as challenges to be overcome . Rather than dismissing UFO reports out of hand , they considered how such objects might function . This perspective , argues Swords , " contrasted markedly with many scientists ' characterizations of such concepts as impossible , unthinkable or absurd . " Writing , submission and evaluation . According to Swords , the " Estimate " was probably completed in September 1948 . The " Estimate " also argued that UFO reports might closely coincide with the approach of the planets Mercury , Venus or Mars to Earth , that the UFOs might be using the planets as launching bases , and predicted a wave of UFO reports in mid - October . In late September or early October , 1948 , the " Estimate " was approved by Colonels William Clingerman and Howard McCoy ( Sneider ' s superiors ) , who then submitted it to the office of General Charles Cabell , the chief of Air Force intelligence . According to Swords , The Pentagon went into an " uproar " over the " Estimate " , which generated " intense " debate . Cabell was newly appointed , and found himself in charge of a " split house " : some were sympathetic and intrigued , if not entirely convinced of the " Estimate " s accuracy , while others rejected the very idea of interplanetary saucers as impossible . Unsure of how to proceed , Cabell eventually submitted the " Estimate " to his superior , General Hoyt Vandenberg , Chief - of - Staff of the U . S . Air Force . Rejection . According to Ruppelt , the " Estimate " was rejected by Vandenberg primarily due to lack of supporting physical evidence , and was " batted back down " the chain of command . In a letter dated November 3 , 1948 , Cabell wrote to Sign , via McCoy , describing flying saucers as real , but rejecting the interplanetary hypothesis and asking for another Estimate . Cabell wrote : McCoy responded in a somewhat defensive letter dated November 8 , 1948 . He noted that many of the UFO reports were misidentified everyday phenomena ( see Identified flying object ) , but also restated the rejected ideas of the " Estimate " without explicitly endorsing the interplanetary hypothesis ; as Swords writes , " [ Project Sign ] just had their knuckles rapped , so they defended themselves . " McCoy wrote , Aftermath . When Sign personnel refused to abandon the interplanetary hypothesis , many were reassigned , and Sign was renamed Project Grudge in 1949 . According to Ruppelt , " The " Estimate " died a quick death . Some months later it was completely declassified and relegated to the incinerator . A few copies , one of which I saw , were kept as mementos of the golden days of the UFOs . " Publicity . The first public report of the " Estimate " was in Captain Edward J . Ruppelt ' s 1956 book , " The Report on Unidentified Flying Objects " . He wrote : Clark notes that " No copies of this near - legendary document have surfaced since . " Denial of existence . Ruppelt ' s 1956 book , which first publicly disclosed the " Estimate " , was cleared by the Air Force . Clark writes ( Clark , 1998 ) , that as late as 1960 , Air Force officials denied that the " Estimate " was real , despite the fact that censors had approved Ruppelt ' s book a few years before . According to Clark , the U . S . Air Force later formally admitted the " Estimate " was real , but Clark ' s bibliography does not make clear what statement or document confirmed the " Estimate " s reality . Additionally , according to Clark , the " Estimate " s existence was confirmed by U . S . Air Force Major Dewey J . Fournet , who as an Air Force major in the Pentagon served as liaison with official UFO project headquartered at Wright - Patterson Air Force Base in Dayton , Ohio . Fournet has been described as being " unimpressed " with the Estimate , and was furthermore quoted as describing the ET conclusion as an " extreme extrapolation " based on scant evidence . An Air Force consultant , astronomer Dr . Allen Hynek , also verified the Estimate ’ s existence . Roswell UFO incident . In the early 1980s , researcher Kevin D . Randle said he spoke with an unnamed colonel who claimed to have helped write the " Estimate " when he was a lieutenant . According to the colonel , when Vandenberg was sent a working draft of the report , he allegedly ordered the paragraphs giving physical evidence ( metal recovered in New Mexico ) removed from the report . After doing so , Vandenberg then rejected the final version as lacking physical evidence . Randle claimed that he realized the significance of this anecdote only a few years later , while investigating the 1947 Roswell , New Mexico crash . According to Randle , the colonel had died by that point , and a follow - up interview was not possible . The McCoy letter of November 8 , 1948 , which mentioned that there was no physical evidence of extraterrestrial origins for flying saucers , has sometimes been cited as evidence against the Roswell UFO incident of July , 1947 , where a UFO allegedly crashed in the New Mexico desert . Swords argues that the McCoy letter should not be interpreted this way , because the U . S . Military usually operates in a highly compartmentalized , need to know basis . If something as extraordinary as an alien spacecraft had crashed in the summer of 1947 , Swords contends that fact would have almost certainly been quickly suppressed , and that Sign would not necessarily have been informed of it .