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PRO reference DEFE 31/118 (also AIR 22/93), Air Ministry Secret Intelligence Summary

[Prepared for Assistant Chief of Air Staff (Intelligence), Air Ministry, by D.D.I (Tech) and published in AMSIS, March 1955].



“An Object was reported....”

The origin of the term “flying saucer,” as applied to strange objects sighted in the sky, remains obscure, although authorship is claimed by a British journalist. According to him, whilst sitting in a Bronx cafe talking with three New York reporters, one of whom was doodling on a piece of paper, he observed that the drawing looked like a “flying saucer.” One of the Americans decided that they “had something” there and, within the hour the term was in use. Within two, it is claimed that ninety people had reported having seen one.

Man has always instinctively looked to the sky for signs and portents, nor has he, even to-day, quite lost his inclination to discern and report celestial manifestations. It is not the object of this article to decry or deprecate such reportings - as Shakespeare wrote “There are more things in heaven and earth Horatio, than are dreamt of in your philosophy” - but it is the intention to encourage a rational approach both to the objects themselves and to the method of their reporting.

Generally, reports are of commonplace objects which would normally pass unobserved but which attract attention in the light of more sensational stories, and lend support to them. Thus a meteor or a radio sonde balloon, or even a conventional aircraft, assume in the perception of some observers speeds, shapes and movements which are entirely uncharacteristic. A well-known astronomer has declared that his experience of the reports of ordinary observers prompts him to reject 95 per cent of what they say, particularly when he knows that they have been startled by some sudden phenomenon which they could have observed for no more than a few seconds.

With such reports we are not seriously concerned. There are a number of other reports on flying saucers which are emphatic statements of visitations from neighbouring planets, and suchlike; these derive both from the imaginings of zealots, admittedly quite serious and sincere in their beliefs, and from charlatans.

Visual Sightings

Reports of sightings themselves reveal certain stereotyped patterns. They usually describe objects as being projectile-shaped, round, oval, or ellipsoidal; they are dazzling-bright, light, shiny, blue-green and generally speaking, iridescent. They move at fantastic speeds in lateral and longitudinal directions; they also hover. Such are the basic lines of description, with inevitable variations.

Practically all of these objects can be roughly identified as follows:-

a.) conventional aircraft viewed by the observers from unaccustomed angles
b) present-day jet aircraft, flying at great speeds and great heights, mistaken by untrained and, on occasion, by experienced observers.
c) sunlight reflections from aircraft and balloons which themselves are too distant to be observed
d) car headlights reflected on low cloud
e) meteorological, radio sonde and cosmic research balloons of all types
f) bright meteors and fireballs
g) planets observed at certain times of the year
h) birds
i) cloud formations
j) meteorological phenomena, such as mock moons and mock suns

There are other reports of visual sightings which are admittedly very strange and difficult to classify. They tell of objects which appear to change shape quickly, which move erratically and at fantastic speeds across the sky. Under no consideration could these reports be classified in terms of the objects listed above. It is firmly believed that these reports are made in all sincerity and are in fact actual sightings - but of reflections from conventional objects.

To give a simple and practical illustrations, consider the erratic movements of the reflection on a ceiling from a mirror held under a light and moved even slightly by hand. Similarly, on a vaster and more extended scale, reflections from planets, meteors, aircraft and objects on the ground may be projected on to cloud formations and haze. Then there are the sightings of those planets which are low on the horizon at certain times of the year and which appear to change colour and move erratically, at fantastic speeds, when observed through haze, or misty atmospheric conditions.

Many reports of such sightings have been received and here is an example of a particular instance where a satisfactory answer was provided. A report made by an experienced B.O.A.C. pilot of a sighting at 19,000 ft. over Goose Bay, Labrador, on Wednesday, 30th June, 1954, stated that objects had been observed, one primary and six secondary, which “accompanied” the B.O.A.C. aircraft for a distance of about 80 miles; all the time they were under observation, the main object was constantly changing shape. An investigation was carried out by the Americans who obtained a subsequent report from a ship at sea in the same vicinity. They described what was apparently the same phenomenon. Members of the ship’s company, however, definitely identified the sighting as the planet Mars, and gave full details of the mirage conditions which were prevailing on that day.


Of photographic evidence little needs to be said. There is nothing in the world more easy to fake than a photographic film or plate and the majority of photographs which have been seen certainly invite suspicion. There are the few pictures that have been published in the press from time to time which are obviously of natural phenomena, such as mock moons and suns, and which emphasise the probability that the objects in the others are faked.

The two reproductions illustrate clearly the considerable opportunities for faked photography on this subject. One in particular could, so easily, be an industrial or operating theatre lamp-shade complete with bulbs.

Radar Sightings

Radar “sightings” constitute the remaining source of flying saucer reports and these reports, generally speaking, fall into certain explainable categories.

Radar Echoes

Radar echoes can be produced by a variety of objects, not all of which are visible to the human eye. The majority of solid objects which return radar energy produce responses on the radar operator’s tube which are easily recognised: moving objects such as aircraft and birds are normally readily identifiable by the size and shape of the response and by the velocities, altitudes and movement they exhibit. Meteorological balloons might also be included in this group of identifiable objects as they normally produce quite distinctive echoes, particularly as many of them carry reflectors specially designed to assist in the plotting of their course by radar. However, some balloons, such as those used for ionospheric sounding, fly at altitudes beyond the reach of aircraft and travel with the upper winds at speeds often in excess of 100 m.p.h. Radar returns from such balloons, when first encountered, could mystify a radar operator and give the impression that a flying saucer has been sighted. On the rare occasions when reports of unidentified objects have their origin in one of these solid bodies it is usually a comparatively simple matter to identify the object by enquiries addressed to the appropriate authority.

Within a group of radar targets which are not controlled or released by man can be included birds, meteorological and astronomical targets. Birds are of little concern as their smallness prohibits responses from them except at very short ranges but, from the other targets, responses with quite unusual characteristics may be obtained.

Echoes from Precipitation

Radar echoes may be produced by condensed water vapour in the form of raindrops, ice crystals or snow, a phenomenon which has been put to good use in civil aviation to assist pilots in avoiding dangerous cloud formations.

Responses on a radar tube from these targets may cover a considerable area, exhibit irregular, diffused boundaries and have a rapidly fluctuating intensity. Movement will generally be related to the speed of the main air current in which the rain is situated, and it may be anything from zero to 100 m.p.h. or more, whilst the target altitude may range from ground to 40,000 ft. Generally the nature of the target is obvious by its size and by the pattern of the responses, but the picture changes with time and may appear unusual and confusing to an inexperienced operator.

Non-Standard Atmospherical Conditions

Under certain meteorological conditions inhomogeneities occur in the atmosphere, and these may be responsible for some unusual radar echoes. The required condition can occur up to heights in the order of 200 miles but the strength of signals returned from such nebulous targets is likely to be too low to produce a distinguishable response except on very rare occasions. Perhaps it is this very rarity which assists in the creation of another saucer.

Unusual meteorological conditions can also cause radar signals to be returned from objects at distances far in excess of the normal range of the radar equipment. Responses caused by this anomalous propagation are superimposed on the usual radar picture of the area and can lead to confusion. The effect occurs most frequently in tropical and sub-tropical areas and usually persists for an appreciable time, sometimes for an hour or more. The effect is well known and because of its relative stability and duration would not normally give rise to unusual reportings.

Ionised Gases

It has been suggested that ionised gas clouds in the atmosphere produce a type of radio echo which may be confused with those from tangible objects. Although radio energy is undoubtedly reflected and refracted by ionised gases (long distance, short wave communications depend on this very fact) the effect falls off very rapidly above, say, 30 Mc/s, whilst 60 Mc/s appears to be the upper limit at which it has been recorded. Some of the early radar equipment still in use does operate within these frequency limits but it is quite incapable of the definition necessary to contribute to the notion of flying saucers. Further, except for the very short-lived effects in the wake of meteorites, ionised gases in quantities required appear rarely to exist at heights as low as 35 miles.

Meteors and Meteorites

It has been known for many years that radio energy is reflected by meteors, and knowledge of the fact has proved valuable in the hands of astronomers. Meteors reach the outer fringe of the earth’s atmosphere in numbers as high as 100,000 per hour but only very few survive long enough to come within the range of radar, the majority being vapourised by frictional heat. Meteors approach the earth at all angles of incidence, from vertical to glancing, and at velocities in the order of 10,000 m.p.h. Radar responses from these astronomical targets appear to be rare, but such targets may produce responses at any range or altitude, subject only to the capabilities of the radar set itself and to the size of the meteor.

Unlike aircraft and balloons the presence of these meteorological and astronomical targets cannot be verified after the event except in the most general way: by carefully sifting operators’ reports, and studying meteorological conditions on the paths of expected meteor shows at the time of the incident, it is often possible to produce a tentative explanation for the responses but, because of the transitory nature of the target, it is seldom conclusive.

Radar Equipment Interference

Another possibility which deserves consideration is interference from other radar equipment. Generally, the cause of this type of spurious response is immediately obvious, but it can happen that the characteristics of the two radar sets bear such a relationship that the interference gives rise to one, sometimes two, bright spots on the radar tube, which may for a short time exhibit some of the characteristics of an actual target. Even in this case, the true nature of the response can usually be quickly determined except when the interfering radar set is mobile and the operator is unaware of its presence.


The investigation of reports of flying saucers presents very apparent difficulties, the major one of which is that, ninety-nine times out of a hundred, the scent is completely cold. It is only fair to point out that in every other case, i.e. when reports are telephoned and promptly checked on the spot, the sighted object has been identified as a balloon or a conventional aircraft. For the investigation of “cold scent” reports there are various media through which information and assistance are obtained: the Royal Observatory and the Meteor Section of the British Astronomical Association give information on meteors, fire balls and all astral phenomena; the Meteorological Office, Royal Air Force Station, Cardington, London Airport and Bristol University cover radio sonde, cosmic research and other balloons; Fleet Air Arm and Royal Air Force units and formations give details of aircraft movements; and the civil police assist in the investigation of all types of reports.

From these sources has come most of the information leading to the true identity of reported flying saucers, and their co-operation in the tedious process of investigation in invaluable. An instance is given of a report by a man who, returning home late one night, stated emphatically that he had seen a flying saucer hovering in a field quite a short distance from his point of observation. The “thing”, according to his story, hovered and moved slowly up and down. Evidence was obtained from the local police to the effect that on the night, at that time, and in that place, an unfortunate farmer had lost a hayrick by fire!

Generally it can be accepted that, of all reports received, the vast majority are of things identifiable as one of the conventional objects enumerated above; the remainder are unexplained because the evidence is either too sparse, too vague, or too contradictory.

As a matter of interest, where the reports received are explained it is mainly in terms of meteors, planets, balloons and aircraft. Noteworthy among the other explanations are included aircraft with rocket-assisted take off, car headlights reflected on low cloud, and the recently adopted navigation lighting system of American civil aircraft.


The civilised world has become conscious or, perhaps it would be more apt to say, it has been made conscious of flying saucers or unidentified flying objects: whenever an airborne body is not clearly recognised as something conventional it becomes a mystery whose magnitude varies according to the observer’s susceptibility. Most people are very susceptible to the influence of the Press or the radio. A news item on a flying saucer promptly induces a spate of reported new sightings.

Sensible and rational reporting of unidentified flying objects is the duty of all who are concerned with flying. Apart from astral or meteorological phenomena, which are of interest to specialists in these matters, there is always the chance of observing foreign aircraft of revolutionary design. As for controlled manifestations from outer space, there is no tangible evidence of their existence.

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