Why (and what are) IFOs?

It has long been accepted within Ufology that the vast majority of "UFO" reports are, in actuality, misperceptions of natural stimuli. However, many non-ufologists find this concept difficult to accept. How can this be, when (in most cases) these reports are made by normal members of the public, with average - often above-average - levels of intelligence and education? What of sightings where witnesses state, adamantly, that "they know what I saw"? What of sightings - evaluated as IFOs by UFO researchers - which involve "trained observers" such as pilots and policemen? And, anyhow, wasn't all this IFO stuff made up by the U.S.A.F in the 1950's, to "cover up" the existence of UFOs?

Many of these popular views regarding IFOs are themselves misconceptions! To begin with, the term "UFO" invokes in many the image of an exotic disc-shaped object , bedecked with a dome, aerials, portholes and running-lights. It is therefore unsurprising that many can only conceive of them having an extraordinary - even extraterrestrial - origin! In reality few witnesses claim observations of such exotic forms; with about 70% of unevaluated "UFO" reports relating only to nocturnal sightings of distant pin-points of light, blobs, squiggles and other vague luminous shapes. This in itself does not rule out an exotic origin for these sightings - but does increase the likelihood of such "UFO" events having an mundane cause.

It should also never be forgotten that that the term "UFO" merely equates to "Unidentified Flying Object". It does not (in itself) guarantee an exotic origin for a given report, only that those who saw the "UFO" were unable to identify it. A person more knowledgeable in the appearance of astronomical, aviation or meteorological phenomena could very well easily recognise what was actually observed in that particular instance.

And, unfortunately, many such "UFO" reports do indeed have down-to-earth explanations. On detailed examination, viable rational solutions are found for approximately 85-95% of all reported "UFO" sightings. This high degree of misperception is factual - rather than mere official propaganda - as approximately the same IFO/UFO ratio appears both in official statistics and figures complied by UFO researchers.

But why is this the case? Well, it is all too easy for an observer to be confronted with confusing perceptual information. Mundane objects can be observed at unfamiliar angles, or under unusual environmental conditions. Either (or both) of these situations can easily endow a mundane object with strange - if false- attributes.

Explainable "UFO" sightings are termed IFO's( Identified Flying Objects). The number of mundane phenomena able to generate false UFO reports is vast. In the mid-1970's it was estimated that there were around 150 separate natural and man-made objects capable of generating spurious "UFO" events(1). However - fortunately for UFO researchers - around 65% of all IFO sightings are instigated by only six different kinds of natural stimuli. The remaining 35% (or so) are generated by a wide variety of other prosaic phenomena.

It should be noted that most IFO events relate to phenomena more clearly seen - or only visible - at night. The number of such natural stimuli are both great and diverse; ranging from aircraft lights, satellites, bolide meteors to stars and planets. In addition to this, the nocturnal environment itself is more conducive to generating IFO effects. Under these conditions the human perceptional system has to process visual stimuli under less- than-perfect circumstances. With poor light and background environmental details obscured by the cloak of night, it is virtually inevitable that natural stimuli are misconstrued under such visually-treacherous conditions!

Another important fact to remember is that there are - as far as UFO events are concerned - no "trained observers". In ufology the myth of the "infallible" trained observer is a long-entrenched one, often defended with zeal by UFO researchers( who should frankly know better!). The fallacy of this concept can be objectively demonstrated by any collection of reliable IFO statistics. For example, the famous American UFO study conducted by Allan Hendry during the late 1970's discovered that 75% of all "UFO" reports made by Pilots were actually IFOs. This figure ran at 94% in regards to reports made by Law Enforcement officials. Compare this with the approximately 87-88% IFO reporting rate by Clerical and Manual workers in that same study (2).

Although - as the figures show - aircraft pilots are indeed more familiar than most to natural aerial manifestations, it is also equally clear that they can be mislead, quite often, by IFO effects. Although an individual well versed in the appearance of (say) astronomical phenomena will be aware of the appearance of stars and planets, they will be less familiar with IFO effects involving aircraft and birds. The reverse goes for aircraft pilots! In regards to police officers, although they are trained to be accurate and meticulous observers, they are not trained to recognise astronomical and aviation stimuli! Hence their high IFO recognition-"failure" rate; which is also attributable to them often being placed in situations which can easily "generate" a UFO report (i.e. working late at night, being called out to "deal" with a UFO sighting made by the public, and so on).

Let us now examine the most common forms of IFO stimuli, which appear time and again in countless IFO reports....

Aircraft and Helicopters.

A large percentage of "IFO" reports involve airplanes and helicopters. Of these, many relate to nocturnal sightings of an aircraft's running-lights. Depending on it's angle in relation to a witness, anything from one to four (or more) lights may be observed. Aircraft lighting follows strict rules laid down by the Civil Aviation Authority (C.A.A). By international regulation, an aircraft must bare a white light on it's tail, a green and red light on it's left & right wings respectively, and have two red flashing lights on it's fuselage. Alternatively, bright white strobe lights may be placed on the wings and tail, in substitution of the above-mentioned lumination. All aircraft are also equipped with extremely bright forward-facing white landing lights. These may be switched on long before touchdown in misty, nocturnal conditions. In any event they can be seen visible from a considerable distance. An observer's mind is inclined to play "dot-to-dot" with these various running-light configurations, resulting in a wide diversity of weird and wonderful (but illusory) forms. In recent years it has also become fairly common to see aircraft who's fuselages are laminated with white-coloured "floodlighting".

Over the past decade advertising airships have become a fairly common sight in the skies of the United Kingdom. These can carry an array of computer-controlled lights attached to a metal grid, positioned on each side of the airship's gasbag. When activated, it acts like a luminated bill-board; the lights displaying a repeating sequence of advertising messages. If the airship is close to an observer (and the message is clearly visible) no phantom "UFO" sightings results. However, if viewed from an unusual angle it can present a confusing, chaotic pattern of lights to the unaware observer. If the advertising sign is suddenly turned off, it can create the illusion of a "UFO" which appears to mysteriously vanish. In any event, it is common for the airship's gasbag to be "floodlit"; a sight sufficiently "flying saucer"-like in itself to generate "UFO" reports! In the USA, light aircraft are commonly used for this activity. In UFO circles they became notorious due to the Hendry study, which ascertained they generated around 22% of all spurious "Nocturnal Light" type reports (3).

Another type of aircraft using non-standard lighting configurations are military in-flight refuelling tankers. They can utilise a variety of body illumination; from an array of many white lights located on their wings and fuselage, to a few extra non-standard lights on it's wings, body and around the refuelling "probe". Furthermore, the lights of any aircraft trailing behind the tanker, awaiting to be refuelled, can also look mysterious. This can either create the illusion of a gigantic dark-bodied "UFO" or of a group of "flying saucers" moving in formation. Air-to-air refuelling operations usually occur at high altitudes; the considerable distance involved effectively "muffling" the aircraft's engine-noise.

Even aircraft observed in daylight can occasionally generate IFO events. If directly approaching an observer, a 'plane can assume the appearance of a "humped" disc or - if viewed sideways-on during a sunny day -a shiny disc or cigar (it's wings obscured by distance, angle and the sun's glare).

Stars & Planets.

False UFO sightings based on very bright stars or planets are also very common; in fact one of the "top three" causes of IFO events! Planets tend to be mistaken more often as "UFO's" than stars because of their greater brilliance. The majority of astronomically-based sightings relate to stationary forms resembling a single pin-point of light (or a vague luminous oval, disc or triangle), usually visible for ten minutes or more. Venus causes the majority of planetary-based IFOs, followed by Mars, Jupiter and Saturn. In the UK, most star-related IFO events are generated by Sirius, with Arcturus, Vega and Capella (and a few others) being responsible for the remainder.

Stars and planets are subject to many adverse perceptional and atmospheric effects.

Astronomical bodies - especially those near the horizon - may repeatedly and rapidly "flash" a sequence of different spectral colours (usually red, green and blue). These stellar prismatic performances are attributable to atmospheric turbulence; the same phenomena - when less severe - responsible for "twinkling" stars.

Otherwise unnoticeable minor involuntary eyeball movements become starkly apparent on viewing a bright light against a dark, featureless background. This phenomena (termed the "Autokenesis effect") crops up in "UFO" reports where a bright stellar body is viewed under conditions similar to that mentioned above (ie a dark, virtually featureless expanse of night sky). This causes the body concerned to exhibit illusory - but nonetheless very realistic-looking - erratic darting "motions", which are confined to a small area of sky. Similar motions (due to minor hand tremor) can be induced by viewing an astronomical object through hand-held binoculars, telescope or camera.

An additional illusory effect (termed "Lateral Motion") can result if an observer views a stellar body while in a moving vehicle. Under these circumstances, the star or planet concerned will appear to travel in the same direction as the vehicle, stopping and starting whenever that vehicle does.

Even the Moon has been mistaken for a "UFO", on numerous occasions. It's appearance can be distorted either by thin cloud, mist or dust. The Moon can also be distorted by atmospheric refraction effects when close to the horizon (i.e. when it is about to rise or set; or in some cases has already done so!). In either case, the Moon's colour can be altered to an eerie orange or reddish hue. It can also be transformed into a receding (or approaching) "saucer" shape "UFO" as clouds obscure (or passes over) it's disc. The moon is not infrequently reported as a UFO! The moon's shape can be changed by thin cloud; taking on odd shapes for many minutes. In some instances such an effect may make the moon resemble a "dome" or "saucer" slowly receding from an observer (as cloud slowly drifts over it's disc).

Bolides And Satellite Re-Entries.

A sizable number of IFO incidents relate to Bolides; spectacular, giant-sized shooting stars, usually observed at night. Bolides are often perceived possess a spherical shape, or resemble a "cigar" or "disc" with "window lights". The latter illusion - termed the "Airship Effect" - is caused by sections of the bolide fracturing off during "flight", which follows the same trajectory as the originating "parent" mass. In any case, a bolide is normally associated with a long, incandescent trail. They follow continuous straight or curved trajectories, and may change colour in flight (as it's body is heated by atmospheric friction). It's demise can be spectacular - often exploding violently with a loud bang. Bolides normally have a duration of 10 seconds or less, but may be visible for anything up to 30 seconds on some rare occasions.

Since 1957 an increasing number of events involve observations of man-made material from space (such as expended rocket-booster tanks or old satellites) re-entering the atmosphere. Their appearance and attributes are more or less identical to that of Bolides, although they move slower and are visible for around two minutes.

Laser Light Displays

Following their entry into widespread use during the early 1980s, laser-light displays have now become a major source of false "UFO" reports. Those unaware of their actual nature describe observing a multitude of smoky white lights, performing swift, repeating rhythmic motions. These include circling (and other geometrical patterns), which also usually involves the lights meeting at a single point and then shooting away. Alternatively, they can be seen as a "dark spinning disc" with white lights "running around its edge", or simply as a rotating "ring" composed of many lights. They may be visible for many hours, from about 7.00pm to usually not later than 02.30am the next morning. Laser-light displays can be seen from a considerable distance if the prevailing cloud-base is fairly high(4).

Weather Balloons

The majority of incidents involving misperceived weather balloons occur during the day - and are responsible for around almost half of all spurious daylight UFO events. Most of these incidents do not involve the small, relatively common "radiosonde", but very large balloons launched to accumulate upper atmospheric data. The radiosonde bursts within an hour or so of launch, but these larger research balloons can endure for many weeks, and may travel a great distance during that time.

Balloons usually manifest as a small, distant slow-moving object with a pin-point, spherical, tear drop, triangular or discoid form. Their colour is dependant on the prevalent lighting conditions; white or slivery on a sunny day, greyish when overcast. If seen at around sunset a balloon can be seen to slowly change colour, from white to red. This is due to the sun's light being affected by refraction while at a low elevation, which the balloon subsequently reflects. Balloons usually drift with the wind, but if caught in a thermal (a rising updraft of air), it can shoot upwards or suddenly change direction. They can also move in a direction opposite to ground winds if they are at a sufficiently high altitude to traverse along the jet-stream.


In recent years, the use of paper luminated balloon-lanterns (commonplace in Asia, where they are traditionally termed 'Khoom Fay' or 'Khom Loy')  have recently become popular in the UK for parties and social functions. These commonly manifest as a cluster of  orange lights sometimes observed rising from the ground and slowly drifting with the wind, eventually vanishing as they burn up. They have a duration of up to several minutes or more. In many ways they are similar to the so-called "fire balloons"  (composed of transparent laundry sacks containing a heat source generating lift (and light) ) used in numerous hoaxes in America from the 1960's onwards - several examples of which are documented in the Condon Report (see below).


Orbiting hundreds of miles above our planet are a host of man-made satellites, used for tasks diverse as telecommunications, scientific experimentation and espionage! Satellites can be seen by earth-based observers due to sunlight reflected from their shiny bodies (which, because of their very high altitude, are luminated even at night). The brighter ones are quite conspicuous. They appear to the naked eye as a single, distant, whitish pin-point of light, traversing along a swift, continuous arch-like path. It may vanish suddenly near the horizon - caused by the satellite becoming eclipsed by the earth's shadow. They can also appear to follow a zigzag path, an illusion again induced by our old friend autokenesis (i.e. involuntary eyeball movement). If almost, or exactly, overhead a satellite may appear to be stationary for a few seconds.

IFO reports based on satellites have become rarer in recent times (possibly due to encroaching "light pollution" rendering satellites difficult to observe in an urban environment. This may well change with the recent introduction of the Iridium satellite system, which are capable of emitting very bright flashes of light (the occurrences of which can be easily predicted). Over the past two decades the MIR space-station had been a noticeable sight over British skies; now replaced by the International Space-Station (IISS), which also inevitably attracts the attention of early 21st century witnesses .

Rarer IFO Types.

The remaining 30% (or so) of IFO events are generated by a more rarefied and diverse collection of natural stimuli. These include Birds, Parachute Flares, Model Aircraft, Airships, Disc-Shaped Silver Helium Balloons and Spotlights . More rarer are IFO sightings instigated by Ball Lightning, Mirages, Clouds, Sun and Moon "Dogs" and Kites with highly reflective "Mylar" surfaces.

Instances where "UFO" experiences have no objective existence are also fairly uncommon, probably comprising around 5% of all IFO events. The These can involve anything from spots before the eyes, "after-images" on the eyeball induced from glancing at bright lights and hallucinations. Few UFO events involve subjective episodes induced either by alcohol or narcotics. Most hallucinatory-based events encountered by Ufologists involve individuals lapsing naturally into rare states of altered mental consciousness (which can occur on the onset of either falling asleep or waking up).

Finally, there are hoaxes; sightings who's details have been totally or mostly fabricated. Most UFO researchers feel that hoaxes only account for about 1%-5% of all sightings (mainly those involving photographs and "Close encounter" - type claims).


Bibliography/Further Reading on IFOs


Unfortunately, most UFO books (especially those published in recent years) tend to skirt the subject of IFOs, or omit to mention them altogether. That stated, a fair number of books have examined IFOs in some detail. A selection of these titles are listed below (the majority of which are, sadly, out of print):

Campbell . S. The UFO Mystery Solved (Explicit Books, 1994).
Condon E.U, (ed) The Scientific Study Of UFOs. (Random House 1969). Now  available at:
Hendry, Allan The UFO Handbook (Sphere 1980).
Klass. Phillip UFOs Explained (Random House 1974).
Randles, Jenny UFO Study (Robert Hale, 1982).

Additionally, various titles released by the American "Sourcebook Project" are also of interest in regards to IFO stimuli. Although not actually about IFOs themselves, they deal with various unusual anomalies of the natural world which could well give rise to "UFO" reports. The titles of this series particularly relevant to this subject are;

Corliss, William Lightning Auroras, Nocturnal Lights.(1982).
Corliss, William Tornadoes, Dark Skies and Anomalous Precipitation (1983).
Corliss, William Rare Haloes, Mirages & Anomalous Rainbows (1984).
Corliss, William The Sun And Solar System Debris (1986).

All published under the aegis of the Sourcebook Project co-ordinated by William Corliss).
Unfortunately, although still in print Sourcebook publications are often difficult to obtain (although some specialist booksellers can get hold of them - albeit after an extensive delay!).


(1): UFO Investigation. BUFORA 1979 (Appendix "11").
(2): The UFO Handbook Hendry, Allan . Sphere 1980. (p.p 102).
(3): Ibid. (p.p 31-34 & 91-92).
(4): For a good description of laser light displays, see "Swirling rings in East Anglia" by Robert Bull (BUFORA BULLETIN Issue No. 4).

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