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Dowding system
The Dowding system was the world's first wide-area ground-controlled interception network, controlling the airspace across the United Kingdom from northern Scotland to the southern coast of England. It used a widespread dedicated land-line telephone network to rapidly collect information from Chain Home (CH) radar stations and the Royal Observer Corps (ROC) in order to build a single image of the entire UK airspace and then direct defensive interceptor aircraft and anti-aircraft artillery against enemy targets. The system was built by the Royal Air Force just before the start of World War II, and proved decisive in the Battle of Britain.
The Dowding system was developed after tests demonstrated problems relaying information to the fighters before it was out of date. Air Chief Marshal Hugh Dowding, commander of RAF Fighter Command, solved the problem through the use of hierarchical reporting chains. Information was sent to Fighter Command Headquarters (FCHQ) central filter room at Bentley Priory and used to prepare a map of the battle. Details of the map were then relayed to the Group and Sector headquarters, where operators re-created the map at a scale covering their area of operations. Looking at the maps, commanders could make decisions on how to employ their forces quickly and without clutter. Instructions were relayed to the pilots only from the squadron's sector control rooms, normally co-located at the fighters' operating bases.
The Dowding system is considered key to the success of the RAF against the German air force (Luftwaffe) during the Battle of Britain. The combination of early detection and rapid dissemination of that information acted as a force multiplier, allowing the fighter force to be used at extremely high rates of effectiveness. In the pre-war period, interception rates of 30% to 50% were considered excellent; that meant that over half the sorties sent out would return without having encountered the enemy. During the Battle, average rates were around 90%, and several raids were met with 100% success rates. Lacking their own direction system, Luftwaffe fighters had little information on the location of their RAF counterparts, and often returned to base having never seen them. When they did, the RAF fighters were almost always in an advantageous position.
Although many histories of the Battle of Britain comment on the role of radar, it was in conjunction with the Dowding system that radar was truly effective. This was not lost on Winston Churchill, who noted that:
All the ascendancy of the Hurricanes and Spitfires would have been fruitless but for this system which had been devised and built before the war. It had been shaped and refined in constant action, and all was now fused together into a most elaborate instrument of war, the like of which existed nowhere in the world.
To counter air raids on London during World War I, Edward Ashmore constructed a system known as the London Air Defence Area (LADA). Ashmore put defensive weapons into three rings around the city, searchlights and anti-aircraft artillery in the outer ring, fighter aircraft in the middle ring, and the innermost ring in the city contained more anti-aircraft guns. Ashmore set up a large plotting table at Horse Guards in London. Information from spotters was relayed to this central room where wooden blocks were placed on a large map to indicate the location of aircraft and other information. Observers around the map could relay this information to one of 25 regional control rooms, who re-created the portions of the map relevant to them and passed the information to the various weapons in their region.
After the war, LADA was run by a War Office department known as Air Defence of Great Britain (ADGB). ADGB was responsible for the defence of the entire British Isles during the 1920s and 30s. LADA became the Metropolitan Area, and ADGB expanded on Ashmore's system to deal with longer ranged and faster moving aircraft. Coloured markers matched coloured areas on a sector clock marking off five-minute intervals. As plots were called in, the plotters used markers with the colour pointed to by the clock, which produced multi-coloured paths of markers on the table making easily followed tracks; the freshness of the information could be determined from the colour of the latest marker. An identical system was later set up in The Midlands.
The system lacked early detection, which was deemed essential as the performance of aircraft improved. Experiments with acoustic mirrors and similar devices were carried out but these always proved unsatisfactory, with detection ranges often as low as 5 miles (8.0 km) even in good conditions. Lacking an alternative, in December 1934, the Air Ministry (AM) made plans to deploy sound detection devices around London as part of the Thames Estuary plan.
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Dowding system
The Dowding system was the world's first wide-area ground-controlled interception network, controlling the airspace across the United Kingdom from northern Scotland to the southern coast of England. It used a widespread dedicated land-line telephone network to rapidly collect information from Chain Home (CH) radar stations and the Royal Observer Corps (ROC) in order to build a single image of the entire UK airspace and then direct defensive interceptor aircraft and anti-aircraft artillery against enemy targets. The system was built by the Royal Air Force just before the start of World War II, and proved decisive in the Battle of Britain.
The Dowding system was developed after tests demonstrated problems relaying information to the fighters before it was out of date. Air Chief Marshal Hugh Dowding, commander of RAF Fighter Command, solved the problem through the use of hierarchical reporting chains. Information was sent to Fighter Command Headquarters (FCHQ) central filter room at Bentley Priory and used to prepare a map of the battle. Details of the map were then relayed to the Group and Sector headquarters, where operators re-created the map at a scale covering their area of operations. Looking at the maps, commanders could make decisions on how to employ their forces quickly and without clutter. Instructions were relayed to the pilots only from the squadron's sector control rooms, normally co-located at the fighters' operating bases.
The Dowding system is considered key to the success of the RAF against the German air force (Luftwaffe) during the Battle of Britain. The combination of early detection and rapid dissemination of that information acted as a force multiplier, allowing the fighter force to be used at extremely high rates of effectiveness. In the pre-war period, interception rates of 30% to 50% were considered excellent; that meant that over half the sorties sent out would return without having encountered the enemy. During the Battle, average rates were around 90%, and several raids were met with 100% success rates. Lacking their own direction system, Luftwaffe fighters had little information on the location of their RAF counterparts, and often returned to base having never seen them. When they did, the RAF fighters were almost always in an advantageous position.
Although many histories of the Battle of Britain comment on the role of radar, it was in conjunction with the Dowding system that radar was truly effective. This was not lost on Winston Churchill, who noted that:
All the ascendancy of the Hurricanes and Spitfires would have been fruitless but for this system which had been devised and built before the war. It had been shaped and refined in constant action, and all was now fused together into a most elaborate instrument of war, the like of which existed nowhere in the world.
To counter air raids on London during World War I, Edward Ashmore constructed a system known as the London Air Defence Area (LADA). Ashmore put defensive weapons into three rings around the city, searchlights and anti-aircraft artillery in the outer ring, fighter aircraft in the middle ring, and the innermost ring in the city contained more anti-aircraft guns. Ashmore set up a large plotting table at Horse Guards in London. Information from spotters was relayed to this central room where wooden blocks were placed on a large map to indicate the location of aircraft and other information. Observers around the map could relay this information to one of 25 regional control rooms, who re-created the portions of the map relevant to them and passed the information to the various weapons in their region.
After the war, LADA was run by a War Office department known as Air Defence of Great Britain (ADGB). ADGB was responsible for the defence of the entire British Isles during the 1920s and 30s. LADA became the Metropolitan Area, and ADGB expanded on Ashmore's system to deal with longer ranged and faster moving aircraft. Coloured markers matched coloured areas on a sector clock marking off five-minute intervals. As plots were called in, the plotters used markers with the colour pointed to by the clock, which produced multi-coloured paths of markers on the table making easily followed tracks; the freshness of the information could be determined from the colour of the latest marker. An identical system was later set up in The Midlands.
The system lacked early detection, which was deemed essential as the performance of aircraft improved. Experiments with acoustic mirrors and similar devices were carried out but these always proved unsatisfactory, with detection ranges often as low as 5 miles (8.0 km) even in good conditions. Lacking an alternative, in December 1934, the Air Ministry (AM) made plans to deploy sound detection devices around London as part of the Thames Estuary plan.
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