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

By February of that year HQ Fighter Command was so concerned by the problem that it ordered a secret investigation of angels by its Research Branch. The two-year probe was to combine the skills of its top radar technicians with the expertise of British ornithologists. Selected RAF radar stations around the east coast were asked to send 35 mm film from their radar cameras which had captured angels for careful analysis. Film and records flooded in and as patterns emerged from the data scientists kept watch over screens to plot the density and distribution of “angels” when they appeared. The investigation quickly disposed of the “temperature inversion” theory as the most likely explanation for all but the most unusual angel reports.

Meanwhile, morbid experiments were carried out to measure the echoing area of various types of birds. Dead animals were obtained from bird sanctuaries and their bodies were wrapped in cellophane and then spun whilst radar was bounced off them to measure their “echoing area.” This was calculated to be around one hundredth of a square metre - similar to that of a bag containing a pound of water!

By 1958 the investigation was concentrated upon one key radar station where angels had been reported with great frequency. RAF Trimingham, near Cromer on the Norfolk coast, was one of the first to be equipped with the Type 80 radar. Ornithologist David Lack used this as a base to carry out spot checks for angel echoes six times every day for eleven months. This revealed the heaviest angel activity occurred during the spring and autumn months, usually at night in calm weather when birds were migrating over the sea at heights from 2-4,000 feet. Lack and his colleagues were able to demonstrate that what the radars were actually seeing were flocks of small birds migrating to and from East Anglia from Continental Europe. He found that autumn was the peak time with skylarks, chaffinches and starlings arriving in huge numbers. The second large movement began in late February when the same species departed, coinciding with the peak times for angel activity.

Further independent evidence arrived in 1959 when staff working with Marconi’s experimental L-band radar at Chelmsford in Essex reported strange “ring angels” on their screens. These began at dawn as a point echo and then expanded to form a perfect ring followed by further concentric rings which had “precisely the same appearance as the ripples on a pond expanding from a point of disturbance.” The ripples were visible to a height of 2,000 feet and it was suspected they might have been caused by pockets of warm air rising from factories or mill chimneys. However, when teams were sent to find the origin point of the rings they could see nothing except open countryside. Then it was noticed that one copse of trees appeared to be covered with starlings. As the scientists watched, at the break of dawn a mass of birds suddenly and silently flew away from the trees in equal directions before arriving at another outer layer of trees. From there they again took off as if in response to an invisible command. These observations, added to the results of Fighter Command’s study, led the RAF to conclude that most “angel” echoes on radar were caused by birds.

But a big problem remained. How could “angels” be eliminated from radar without playing havoc with the tracking and control of military aircraft? The answer was a gadget called ‘Swept Gain’ or Sensitivity Time Control (STC). This automatically reduced the visibility of permanent echoes on the radar picture and increased the strength of those created by aircraft. In the case of angels, it was a simple process to set swept gain controls so that the 0.01 sq metre echoing area of birds were automatically removed from the radar picture – leaving the one square metre aircraft targets clearly visible. This was simplified even further when aircraft were fitted with transponders which transmit an identification signal to ground radar.

During the 1960s radar technology progressed in leaps and bounds as more powerful systems were invented to handle the steady increase in air traffic. Digital computers were then drafted in to take over the complex task of simultaneously tracking dozens of aircraft of all shapes and sizes. In order to sort the wheat from the chaff which clutter air traffic control screens, today noise caused by weather systems, birds, insects and other “spurious echoes” such as might be generated by true UFOs (whatever they may be) are automatically removed by computers at source. This explains why the vast majority of reports of UFOs on radar were made during the 1940s and 1950s, before improved radar and computer technology eliminated them from modern equipment.

Throughout its early history, radar was dogged with technical problems that often led to spectacular misinterpretations of “angels” as enemy aircraft and flying saucers. It is a popular misconception, particularly among UFOlogists, that radar – like the camera -cannot lie and that UFOs “confirmed” by radar must by definition be solid, mechanical objects possibly from outer space. Ministry of Defence records released at the National Archives this year show how far from the truth this notion really is.

Copyright 2005 David Clarke

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