The Secret Files: Ghosts in the Machine > [1 ¦ 2 ¦next]

originally published in Fortean Times 195 (2005)

From the earliest development of radar military sky-watchers were puzzled by mysterious echoes on their screens. In the second in his series on secret files released at Britain’s National Archives, DAVID CLARKE reveals how Britain’s scientists struggled to explain these “radar angels.”

During the 1930s the Air Ministry secretly built a chain of radar stations along the eastern coastline of England that was to provide a crude but effective early warning system against air raids. In 1940 during the Battle of Britain this “secret weapon” gave the RAF a crucial tactical advantage over the superior strength of the Luftwaffe. But although at this time British radar was the most advanced in the world, it was far from foolproof, as was demonstrated by a series of strange incidents the following year.

Late on the night of 20 March 1941, while the threat of German invasion remained, RAF Fighter Command was placed on red alert when its radar chain reported an attack on Britain’s south coast. Up to five separate stations could “see” a massive formation of blips moving slowly across the channel precisely as would be expected if a massive night raid by German bombers was imminent. As tension grew the blips approached from the direction of the Cherbourg peninsula in France until within 40 miles of the Dorset coast. At RAF Worth they lingered on the radar picture for two hours and appeared to change from massed groups to single echoes which then faded out.

The next night the blips were back and engineers were called in to make adjustments that might eliminate “noise” from the system. For a period of weeks stations continued to report both mass formations and individual echoes. Whilst sceptical, senior officers began to fear these could be part of a sophisticated German plot to jam British radar with false signals as aircraft or towed gliders prepared for a real invasion. RAF fighters directed by ground radar were ordered to intercept and shoot down the mysterious objects. But when they arrived at the spot in the English Channel where the echoes were visible on radar, nothing could be seen.

Recalling this incident sixty years later Sir Edward Fennessey, who was responsible for the radar chain, recalled that no explanation was ever found “and because we were busy fighting a war we spent no time investigating this phenomena.” Afterwards he retold the story at a dinner party where he entertained guests with his theory that the echoes were really guardian angels, “the souls of British soldiers killed in France over the centuries returning to defend their country.”

Although it was intended as a joke Sir Edward’s fantasy caught the imagination of serving airmen who were watching “ghosts” on their radar screens. According to the Oxford English Dictionary, from 1947 the term “angels” was commonly used to describe “unexplainable echoes” seen not only on radar pictures in Britain, but across the world. Since the war angels had been reported on a variety of ground radars operating on the short 10cm and 25cm wavelengths. According to one source they often completely covered the screen and “appeared as a cloud of responses very similar to the echoes obtained by small aircraft” precisely as they had in 1941. When they appeared as an individual echo they could easily be mistaken for a fighter-type aircraft as they followed a steady course and were plotted at heights from 2- 10,000 feet.

Angels continued to be seen in the 1950s after the arrival of MTI (moving target indicator) radars, which were meant to eliminate much of the “noise” and ground clutter that plagued early systems. By 1954, when powerful Type 80 radars were installed at the radar research station in Malvern, angels had become a considerable hazard for fighter controllers. Type 80 had far greater range and performance than the wartime radar but was still plagued by angels. On some occasions they polluted radar screens to such an extent that they interfered with RAF exercises. At that time no one had a satisfying explanation for the phenomenon but there were two competing theories. The first was that angels were caused by temperature inversions in the lower atmosphere that created pockets of air which reflected radar beams. But this could not fully account for how the echoes moved against the prevailing winds or in excess of measured wind speeds.

The second theory was that angels were really formations of birds flying to and from their breeding grounds as part of their annual migrations. But ornithologists who were using radar to study bird migrations had a very difficult time persuading the RAF to take this theory seriously. Top brass were loath to admit that creatures as small as birds were capable of disrupting their operations. Events were soon to prove how wrong they were. When inquiries were made, a mass of anecdotal testimony from radar staff came to light that supported the bird theory. During the war staff at coastal radar stations had even correlated “angels” on their screens with flights of seabirds spotted with the naked eye. On rare occasions large individual birds could cause more chaos. Barry Huddart, who was posted at HQ Fighter Command in 1957, recalled one incident “when fighters were scrambled to intercept an echo on a radar screen which turned out to be a Golden Eagle at 25,000 ft in a jet stream, very unusual but nonetheless true.”»

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