page_title: Airborne Cigar
section_title: Airborne Cigar
hierarchical_section_title: Airborne Cigar / History / Airborne Cigar
caption_attribution_description: English: Royal Air Force Bomber Command, 1942-1945. Avro Lancaster B Mark I, ME590 'SR-C', of No. 101 Squadron RAF, lies on the FIDO (Fog Investigation and Dispersal Operation) pipework at Ludford Magna, Lincolnshire, after a successful crash-landing on returning from a raid to Augsburg on the night of 25/26 February 1944. The aircraft was damaged by anti-aircraft fire, which disabled the hydraulic system and holed the starboard fuel tank, and was also attacked by a Messerschmitt Bf 110 night fighter which set it on fire and wrecked the elevators. In spite of the damage the pilot, Sergeant R Dixon, brought ME590 back to Ludford Magna for a belly landing, during which some incendiary bombs which had been hung up in the bomb bay, fell out and caught fire on the runway. The censor has eliminated the large aerial masts above the fuselage which indicated that the aircraft was carrying 'Airborne Cigar' (ABC), a jamming device which disrupted enemy radio telephone channels.
context_page_description: Airborne Cigar, or ABC for short, was a World War II electronic countermeasure system developed by the Telecommunications Research Establishment to jam Luftwaffe ground-to-air radios operating in the very high frequency band. When used properly, the system made communications with night fighters almost impossible. The Germans referred to ABC as "dudelsack", German for bagpipes, in reference to the warbling sound.
  The system consisted of a wide-band receiver and three tunable transmitters of about 50 W output. The German-speaking Special Duties Operators would listen to signals in the band to determine which frequencies were being used by ground controllers. When one was found, one of the transmitters would be turned to that frequency and began broadcasting noise.
  ABC was operated primarily by No. 101 Squadron RAF, part of the specialist No. 100 Group RAF. As the system was only useful over a range of about 50 miles, their Lancasters were spread out through the bomber stream. Because ABC was used on almost all missions, 101 suffered among the highest losses of the war.
  To counteract ABC, the Germans introduced new frequency bands. These were soon discovered and jammed as well.
context_section_description: On 6 May 1943, Air Commodore Sidney Osborne Bufton ordered a version of Cigar that could be fit to an aircraft. This concept naturally became known as "Airborne Cigar", and as a result, the original retroactively became "Ground Cigar". Bufton also suggested that "in view of the brevity and simplicity of the term, it is requested that you refer to 'Airborne Cigar' aircraft as ABC aircraft in future communications." The system was originally intended for fitting to No. 100 Squadron RAF bombers, but as these aircraft were in the process of receiving the new H2S radars, they had no leftover electrical power to run the ABC system. Thus No. 101 Squadron RAF was selected, operating the system for much of the war.
  Building such a system was not easy; high-power VHF transmitters of the era were quite large, and to be effective an aircraft would have to carry several in order to spot-jam different working frequencies. Ultimately the system consisted of three transmitters broadcasting from two 7 foot (2.1 m) antenna masts above the wing, with a single specialized receiver and its shorter antenna mounted near the tail of the aircraft. The transmitter electronics were packaged into a large cylinder that  massed 275 kilograms (606 lb) and took 3,000 man-hours to install. The bomb load was reduced by about 1,000 pounds (450 kg) as a result. The system was tested 4 to 6 September 1943  and first went into operation on the night of 7/8 October.
  ABC required the operator to listen for any broadcasts in the VHF bands. As these communications were fleeting, they could not simply hunt around the dial looking for transmissions. Instead, a motorized tuner swept the receiver through the entire band 25 times a second. Any signals received were sent to an oscilloscope, causing a vertical "blip" to appear on the display. The horizontal axis of the oscilloscope was connected to a time base generator with the same ​¹⁄₂₅ second period, synchronized to the tuner. Thus, the horizontal position of the blip indicated the frequency of the signal.
  When a blip was seen, the operator would then tune a second conventional tuner to the same frequency and began listening to the transmissions. They would listen for certain key words like "kapelle", giving the target altitude, to identify ground controllers as opposed to other users. To do this, the operator had to have a working knowledge of the German language, and thus many of the Special Duties Operators (SDOs or SOs) were Yiddish speakers, including a number of men who had escaped from Germany before the war. Once  a frequency was identified, one of the three transmitters would be set to jam that frequency and the operator would begin hunting for another signal.
  As the effective range of ABC was on the order of 50 miles (80 km), and the bomber streams were often much longer, the ABC aircraft had to be spread out through the stream. This required many ABC aircraft to fly on every mission. As a result, losses among No. 101 were very high; between 18 November 1943 and 24 March 1944, the unit lost seventeen aircraft. Seven  were lost on the night of 30/31 March during the disastrous Nuremberg Raid, and another four on 3/4 May.
  As was the case for Tinsel, operations were sometimes aided by the Y service's station in West Kingsdown, who would attempt to identify the frequencies and send them to the ABC aircraft using code words. This proved largely ineffective due to range limitations, and ABC was almost always operated purely by the SDOs.
  One of ABC's major uses was during the D-Day invasion. In order to convince the Germans that the invasion was taking place near Pas de Calais, a large force of RAF Flying Fortresses dropped window in patterns that looked like a massive paratrooper landing effort. To protect these aircraft, the entire force of ABC-equipped Lancasters was mustered to utterly disrupt any attempt at interception.
caption: Avro Lancaster B Mark I, ME590 'SR-C', of No. 101 Squadron RAF, lies on the FIDO (Fog Investigation and Dispersal Operation) pipework at Ludford Magna, Lincolnshire, after a successful crash-landing on returning from a raid to Augsburg on the night of 25/26 February 1944. The censor has eliminated the large aerial masts above the fuselage which indicated that the aircraft was carrying 'Airborne Cigar'.
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