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Identified Flying Object is an identified UFO.

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An Identified Flying Object, or IFO, is any unusual or puzzling object or optical phenomenon observed in the sky which can be identified as a known or conventional phenomenon after being investigated by qualified persons. This is in contrast to an unidentified flying object, or UFO, which cannot be identified following investigation.

UFO studies and result differences.

Identified Flying Object.
B-2 Spirit bomber sometimes mistaken for a UFO.

It has been estimated from various studies that 50-90% of all reported UFO sightings are eventually identified, while 10-20% remain unidentified (the rest being "garbage cases" with insufficient information). Various studies have also shown that only a small percentage of UFO reports are deliberate hoaxes (typically less than 1%). Instead, the vast majority are honest misidentifications of natural or man-made phenomena.

The actual percentage of IFOs vs. UFOs depends on who is doing the study and can vary widely depending on criteria and cases examined. Politics can also play an important role. For example, in early U.S. Air Force UFO studies such as Project Blue Book, the unknowns were consistently over 20%. However, in early 1953, right after the CIA's debunking Robertson Panel, the USAF issued Air Force Regulation 200-2 ordering the unknowns reduced to a minimum. As a result, percentages of unknowns dropped precipitously, usually being only a few percent in any given year. When Blue Book closed down in 1970, only 6% of cases overall were now classified as unknowns (the vast majority of the final unknowns arising from before the issuance of AFR 200-2, which ordered Air Force personel to publicly discuss only IFOs and not "unidentifieds."

The following are some major scientific studies undertaken during the past 50 years and the proportion of IFOs vs. UFOs:

  • Project Blue Book Special Report No. 14 (referred to further below as BBSR) was a massive statistical study the Battelle Memorial Institute did for the USAF of 3,200 UFO cases between 1952 and 1954. Of these, 22% remained unidentified ("true UFOs"), using the stringent criteria that all four scientific analysts had to agree that the case had no prosaic explanation, whereas agreement of only two analysts was needed to list the case as explained. Another 69% were deemed identified (IFOs), and for the remainder, 9%, there was insufficient information to make a determination.
  • The official French government UFO investigation (GEPAN/SEPRA), run within the French space agency CNES between 1977 and 2004, scientifically investigated about 6000 cases and found about 13% defied any rational explanation (UFOs), while about 46% were deemed readily identifiable, or IFOs. (The remainder, or 41%, lacked sufficient information.).
  • When the AIAA in 1971 reviewed the results of the 1966-1969 USAF-sponsored Condon Committee study, 30% of the 117 cases remained unexplained. (This is another example of politics clearly affecting outcomes. Condon had claimed in his summary that all the cases studied were or could probably be explained.).
  • Of about 5,000 cases submitted to and studied by the civilian UFO organization NICAP, 16% were judged unknowns.

In contrast, much more conservative numbers for the percentage of UFOs were arrived at individually by astronomer Allen Hendry, who was the chief investigator for the Center for UFO Studies (CUFOS). CUFOS was founded by astronomer Dr. Allen Hynek (who had been a consultant for the Air Force’s Project Blue Book) to provide a serious scientific investigation into UFOs. Hendry spent 15 months personally investigating 1,307 UFO reports.

In 1979, Hendry published his conclusions in The UFO Handbook: A Guide to Investigating, Evaluating, and Reporting UFO Sightings. Hendry admitted that he would like to find evidence for extraterrestrials but noted that the vast majority of cases had prosaic explanations. He deemed 89% IFOs and only 9% unidentified. If only "hardcore" cases -- well-documented events which defied any conceivable conventional explanation -- the figure for UFOs dropped to only 1.5%.

One possible reason for Hendry's more conservative results might be that he was operating from a very different set of data. Hendry examined almost exclusively civilian reports, mostly from inexperienced witnesses. In contrast, government studies, such as the U.S. Project Blue Book or the French GEPAN/SEPRA, or the civilian NICAP study, contained large numbers of civilian and military pilot sightings and other military sightings, usually considered to be higher evidentiary cases because of the greater experience of the witnesses and the presence of corroborating data such as radar.

As an example of the difference, military personnel made up only 1% of Hendry's witnesses, but 38% of the Battelle / Air Force study. The military witnesses also contributed a much higher percentage of "excellent" or "good" cases (58% for the military vs. only 33% for the civilian cases), which were more likely to be judged unknowns in the Battelle study. Overall, 29% of military cases were judged as unknowns vs. 17% for civilian cases.

Because the results for the Battelle BBSR study and Hendry’s CUFOS study are readily available and contain many statistical breakdowns of cases, they will be contrasted in detail below.

Battelle Memorial Institute breakdown of cases.

Out of 3,201 cases, 69% were judged to be identified or IFOs, 22% were unidentified or UFOs, and 9% had insufficient information to make a determination. Only two of four scientific analysts had to agree for a case to be listed as an IFO, but all four analysts had to agree for it to be judged a UFO. About twice as many of the excellent cases were judged UFOs as the poorest cases. The difference was accounted for mostly by cases judged having "insufficient information", which was only 4% for the best cases but 21% for the worst. Quality of cases didn’t seem to have much effect on the various category percentages for the IFOs, except in the "psychological" category, in which the poorest cases had much higher relative rates.

Breakdown by category of IFO and case quality.

Astronomical 22% 24% 23% 19% 23%
Aircraft 22% 19% 22% 25% 16%
Balloon 15% 12% 17% 17% 13%
Light phenomena 2.2% .9% 2.4% 2.9% 1.1%
Birds 1.0% 0.9% 1.0% 1.2% 0.7%
Clouds, dust, etc. 0.4% 0% 1.0% 0.4% 0%
Psychological 2.0% 0% 0.5% 3.3% 3.3%
Other 5% 5% 5% 5% 6%
Insufficient information 9% 4% 4% 14% 21%
Unknown origin 22% 33% 25% 13% 17%

BBSR further broke these results down based on whether the identification was considered certain or merely doubtful. For example, in both the astronomical and aircraft IFO categories, 12+% were considered certain and 9+% were doubtful. Overall, of the 69% listed as IFOs, 42% were thought to be solved with certainty, while 27% were still considered doubtful.

In addition, if a case was lacking in adequate data, it was placed in the insufficient information category, separate from both IFOs and UFOs.

Based on these results, the percentage of unknowns increased significantly with the quality of the cases. This is contrary to the contention of many skeptics that the remaining unidentified cases are the result of poor quality reports or insufficient information.

Military vs. civilian breakdown.

IFOUFOInsufficient Information
Best reports 65% 72% 68% 32% 24% 28% 2% 4% 3%
Worst reports 70% 70% 70% 24% 14% 16% 7% 17% 14%

The Battelle BBSR study consisted of many internal military reports; fully 38% of the cases were designated as military. Military witnesses tended to submit better quality reports, had much fewer reports rated as having insufficient information, and had higher percentages of unknowns. As in the previous breakdown, the percentage of UFOs again rose with case quality for both the military and civilian subcategories.

In the summary table, best reports are those rated excellent and good; worst reports are doubtful" and poor.

Comparison of IFOs to UFOs by characteristics

A key study of BBSR was to statistically compare IFOs and UFOs by six characteristics: color, number of objects, shape, duration of observations, speed, and light brightness. If there were no significant differences, the two classes were probably the same, the UFOs then representing merely a failure to properly identify prosaic phenomena that could already account for the IFOs. On the other hand, if the differences were statistically significant, this would suggest IFOs and UFOs were indeed distinctly different phenomena.

In the initial results, all characteristics except brightness tested significant at less or much less than 1% (brightness was greater than 5%). By removing "astronomical" sightings from the "knowns" and redoing the test, just two categories, number and speed, were significant at less than 1%, the remainder having results between 3% and 5%. This indicated that there was a statistically significant difference between the characteristics ascribed to UFOs and IFOs, but perhaps not as significant as the initial results suggested. However, for two characteristics, brightness and speed, the significance actually increased with the revised test. Furthermore, even with revision, statistically significant results for six independent characteristics is highly improbable (less than one in a billion, by multiplying all probabilities together), strongly suggesting there was something fundamentally different between the UFOs and IFOs [note: the statistical analysis and interpretation in this last sentence doesn't make sense - needs revision by a statistician].

Allen Hendry study.

Like the Air Force, asronomer Allan Hendry found that only a small percentage of cases were hoaxes. Most were honest misidentifications. Hendry attributed most of these to inexperience or misperception.

Out of 1,307 cases: 88.6% had clear prosaic explanations (IFOs) and 8.6% were unknowns (UFOs). Of the UFOs, Hendry thought that 7.1%, might still have a prosaic explanation while 1.5% (20 cases) had no possible plausible explanation and were completely unexplained. The remaining miscellaneous cases (2.8%) were "garbage" cases, where Hendry deemed the witnesses unreliable, the reports hopelessly contradictory, or lacking in sufficient information.

Overall, in the three major categories, 42% of all cases had astronomical explanations, 37% were aircraft, and 5% were balloons. A further breakdown allowed 77% to be readily explained by five main classes of objects: 29% were bright stars or planets, 19% were advertising planes, 15% were other aircraft, 9% were meteors and reentering space debris, and 5% were balloons of various types (mostly weather or advertising balloons but also a few prank balloons).

Breakdown of cases.

Hendry also used a case classification system developed by his mentor Dr. J. Allen Hynek, who established CUFOS, where the study was carried out. In the following summary table, NL = "Nocturnal Lights", lights seen in the sky at night, DD = "Daylight Discs", objects seen in daytime (but not necessarily disc in shape), RV = "Radar/Visual" cases, objects observed by both witnesses and radar, and CE = "Close Encounter" cases. For convenience, CE cases listed below are combined totals of Hynek’s CE1, CE2, and CE3 cases, where CE1 cases were objects thought to be seen up close (within 500 feet), CE2 had purported physical interactions with the environment (physical trace cases or electromagnetic interference), and CE3 cases were supposed to involve sightings of occupants.

CategoryNLDDCERVTotal CasesPercent
bright stars or planets 360 2 16 2 380 29%
meteors, reentries 113 5 4 0 122 9%
satellites 24 0 0 0 24 2%
moon 22 0 0 0 22 2%
TOTAL (all cases) 519 7 22 2 550 42%
advertising planes 230 0 22 0 252 19%
other aircraft 196 22 6 0 224 17%
missile launches 9 0 1 0 10 .7%
TOTAL 435 22 29 0 486 37%
Balloons 23 35 2 3 63 5%
Birds 5 1 0 0 6 .5%
Clouds, dust 10 2 0 0 12 .9%
Light phenomena (mirage, moondog, ground lights, searchlights, etc.) 9 1 4 0 14 1.1%
Other (kites, flares, reflections windblown debris, etc.) 12 3 1 0 16 1.2%
Cases 1024 71 58 5 1158 88.6%
Percent 78.3% 5.4% 4.4% .4% 88.6%
Cases 79 18 16 0 113 8.6%
Percent 6% 1.4% 1.2% 0% 8.6%
MISC (insufficient information, inconsistent accounts, unreliable witnesses) 36 2.8%
TOTAL all cases
Cases 1103 89 74 5 1307 100%
Percent 84.4% 6.8% 5.7% 0.4% 100%

Analysis of IFOs. Common causes of misidentification and IFOs

Both BBSR and Hendry found that the vast majority of IFOs were caused by three classes of objects or phenomena: Astronomical, aircraft, or balloons. Of all IFOs, 86% were accounted for by these three groups in the BBSR study vs. 83% in the Hendry study. However, there were significant differences in the percentages attributed to each group:

  • Astronomical: BBSR = 22%; Hendry = 42%. Since BBSR predated satellites, subtracting these out of Hendry’s results leaves 40%. In Hendry’s study, bright stars and planets, like Venus, made up 29% of all cases while meteors (and to a much lesser extent, re-entering space debris) made up 9%.
  • Aircraft: BBSR = 22%; Hendry = 37%. The high percentage of military people and pilots in the BBSR study may have something to do with the far lower aircraft misidentification values. Hendry had large numbers of advertising plane misidentifications (19%), perhaps reflecting a study bias toward urban centers, particularly Chicago, where CUFOS is located. Hovering aircraft such as helicopters or blimps, or aircraft that appear to be hovering, such as airplanes seen at night from the front with their headlights on as they approach for landing can often confuse the inexperienced witness, as can aircraft strobe lights.
  • Balloons: BBSR = 15%; Hendry = 5%. Possibly the large numbers of big experimental balloons, such as the Skyhook balloon, launched in the period that BBSR studied, contributed to the higher BBSR percentage.

Rare causes of misidentification of UFOs.

  • Birds: BBSR = 1%; Hendry = 0.5%.
  • Light phenomena: BBSR = 2%; Hendry = 1.1%. Might include mirages, moondogs, sundogs, auroras, ground lights such as street lights, and searchlights reflected off of clouds. Extremely rare light phenomena such as possible ball lightning or earthlights may very rarely trigger UFO reports.
  • Clouds, dust, fog, etc.: BBSR = 0.4%; Hendry = 0.9%. Might include unusual cloud formations such as lenticular clouds, noctilucent clouds, rainbow effects, and high-altitude ice crystals.
  • Other causes: BBSR = 5%; Hendry = 1.2%. Hendry mentioned some of these, such as kites, flares, reflections off windows, and windborn debris.

Some misperceptions of UFOs.

Light distortion from air turbulence can cause celestial bodies to move to a limited degree as can a visual perceptual effect called autokinesis, caused by small, involuntary eye movements after staring at a star-like light against a black background without a frame of reference. To some observers, these may cause stars and planets to appear to start and stop, change direction, or dart around.

Hendry and many skeptics often attribute regular patterns such as "figure eights," "meandering in a square pattern," or "falling leaf motion" to these mechanisms and dismiss the sighting as an IFO, but this is far from certain. Movement caused by atmospheric effects or autokinesis is erratic and very limited in range. Therefore, in principle, such effects cannot cause true regular geometric motion such as a square pattern or figure eight, although perhaps those with vivid imaginations may attribute such patterns to random motion. In the case of autokinesis, the effect is very temporary and is destroyed by refixating one’s gaze. Also autokinesis can happen only in the absence of nearby objects. Thus if somebody was viewing a bright object near a visible horizon or in a field of nearby stars, it is very unlikely that autokinesis would be the cause of perceived motion.

Atmospheric distortion also tends to cause motion limited to only few seconds of a degree (causing the familiar twinkling of a star), and autokinesis is typically less than one degree. As Hendry himself noted, very large and prolonged excursions of motion would rule out either mechanism as a suitable explanation.

According to Hendry, moving clouds may also sometimes confuse observers by creating induced motion. Hendry believes this occasionally makes observers also believe objects have suddenly disappeared or make a rapid departure.

Another type of misperceived motion sometimes occurs when people are driving in a vehicle. Witnesses may believe the "UFO" was following them even though the celestial body was actually stationary. Even police and other normally reliable witnesses can occasionally be fooled by sightings of bright stars and planets.

Similarly, in about 10% of Hendry’s cases caused by celestial bodies, witnesses greatly underestimated distances to the objects, giving distance estimates ranging from 200 feet to 125 miles (60 m to 200 km).

Reentering space debris or meteors may appear as a string of lights. This can occasionally be misinterpreted as lights coming from windows, creating the illusion of a spacecraft. However, such mistakes are actually extremely rare. The effect was first noted in a widely observed 1969 re-entry of a Soviet satellite. The Air Force collected hundreds of reports from witnesses. From these, debunker and astronomer Donald Menzel found three anecdotal cases where witnesses reported the effect. (UFO’s, A Scientific Debate, 155-161). This suggests that perhaps only 1% of all witnesses actually interpret similar events in this way. It is thus a mistake to assert that all reports of elongated objects with windows are due to misidentified meteor trains or space debris.

Venus as an IFO.

Because Venus is the brightest object in the sky (except for the sun and moon) it is frequently misidentified. Contributing to this, Venus is often visible in the early evening and morning sky, and thus seen by many people. Even experienced witnesses, especially when they are in unfamiliar surroundings or atmospheric conditions are unusual, may be confused, at least temporarily.

For example, Astronaut Gordon Cooper, himself a strong advocate of the extraterrestrial hypothesis, also related that he had once been momentarily fooled by the planet Venus when he was a fighter pilot, thinking it a distant enemy plane, and pursued it for several minutes.

Although there is no doubt that Venus frequently triggers UFO reports, it is often overplayed as a UFO culprit by many skeptics. For example, astronomer Phil Plait claimed that Venus was responsible for a "majority" of all UFO reports (Plait, 205). But the studies cited here do not support this. BBSR attributed only 22% of sightings to astronomical causes of all types, stars, planets, meteors, etc. Venus constituted some unspecified fraction of these. "Certain" astronomical identifications were only 13% of cases (the other 9% of astronomical IDs being "doubtful"), which would further reduce the number of actual "Venus cases." Hendry attributed a larger 29% of sightings collectively to "bright stars or planets." Again the fraction believed caused specifically by Venus isn’t broken down, but likely didn’t exceed 20%.

In other cases, some skeptics will claim Venus (or perhaps Jupiter or a bright star) to be responsible for a sighting when they aren’t even visible or are in the wrong part of the sky. Further, sometimes impossible properties are ascribed to Venus in order to debunk prominent UFO cases. In one famous case, known as the Portage County UFO Chase from 1966, two policemen in their car chased a brilliant UFO for an extended period of time; in the end, seven police officers were involved in the pursuit, and about half a dozen civilians claimed to have seen the same or a similar object. The deputies said the UFO was as clearly defined and metallic, roughly the size of a house when they first saw it up close, bathed them and the surrounding countryside in bright light, and flew directly over them at one point. Another set of policemen saw the initial two officers' car and the UFO approaching rapidly from the west while Venus was in the east. Despite this, the USAF claimed, after a cursory investigation (only one of the police officers and none of the civilians was interviewed) the police chased a satellite and then Venus. (This incident was the inspiration for the police UFO chase in Steven Spielberg’s Close Encounters of the Third Kind)

Conclusions about UFO and IFOs.

Whether an unknown flying object is ultimately called an IFO or UFO is a judgment call on the part of the researchers involved, and thus the proportion of IFOs to UFOs will inevitably fluctuate and their significance will remain controversial. As Hendry himself noted, "Reasonable UFO proponents admit that 'genuine’ UFO sightings are in the minority, around 10-20%; the skeptics say, 'If 90% of the reports are IFOs, why not 100%? Actually, there is no way to determine the absolute percentage of IFO and UFO-they keep changing from sample to sample and year to year and are dependent on the biases of the judges."

Many Ufologists argue that IFOs represent the inevitable "noise" encountered in analysis of any phenomenon. Those cases that still defy conventional explanation, even if their percentages are relatively small, constitute the hardcore "signal" of the UFO enigma.

Sources of information on UFOs.

  • Alan Hendry, The UFO Handbook: A Guide to Investigating, Evaluating, and Reporting UFO Sightings, 1979, Doubleday & Co., ISBN 0-385-14348-6.
  • Philip Plait, Bad Astronomy: Misconceptions and Misuses Revealed, from Astrology to the Moon Landing "Hoax", 2002 John Wiley & Sons, ISBN 0-471-40976-6. (Chapter 20: Misidentified Flying Objects: UFOs and Illusions of the Mind and Eye).
  • Carl Sagan & Thornton Page, editors, UFO's: A Scientific Debate, 1972, Cornell University Press, 1996, Barnes & Noble Books, ISBN 0801407400.

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