3.4 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Post Instrument | 3/3 | https://en.wikipedia.org/wiki/Post_Instrument | reference | science, encyclopedia | 2026-05-05T09:43:29.277739+00:00 | kb-cron |
The Observer Corp was an expansion of a system originally set up in World War I to coordinate the reports from observers in the London area, part of the London Air Defence Area (LADA). In this system, originally set up by Edward Ashmore, observers telephoned reports of aircraft to a plotting center in the Horse Guards building in London. Information from the map would then be forwarded to the searchlights and anti-aircraft guns in the LADA area. In the post-World War I era the system was taken over by the Air Defence of Great Britain organization, formally part of the Royal Air Force but containing British Army and Royal Engineer units as well. It was re-organized and expanded, covering not only the London area but adding similar reporting organizations in The Midlands. They also introduced new techniques to deal with faster aircraft. In the new systems, plotters would take the reports from the observers and place a colored marker on a large map inside the indicated grid location. The marker held information about the number and altitude of the aircraft. The marker colors changed every five minutes, based on a sector clock, and when the marker was moved to a new location, a smaller marker was left behind in its former location. This produced a trail of colored markers on the map that allowed observers to easily see the track of the aircraft, as well as estimate how quickly it was moving. The Dowding system was built on top of this reporting system. It added a central filter room that acted as a plotting station for all of the Chain Home radar stations. Reports from the filter room were then forwarded to Group plotting rooms where they were combined with information from the Observer Corps. The same basic system using colored markers indicating the time, altitude and number of aircraft was used throughout the system. Just prior to the war, two additional Groups were added to cover Scotland and the north, and the southwest. Starting in 1942, additional charts were installed at the Group plotting centers that allowed information from neighbouring Groups to be recorded. This was useful for handing over tracks that were moving across Group boundaries.
== Notes ==
== References ==
=== Citations ===
=== Bibliography === Craine, Simon; Ryan, Noel (2011). "Protection from the Cold": Cold War Protection in Preparedness for Nuclear War. Lulu.com. ISBN 9781904098195. Instructions for Observer Posts (PDF) (Technical report). Air Ministry. April 1941. Observers' Tale: The Story of Group 17 of the R.O.C. Roland Brothers. 1950. ROC Training Manual (PDF) (Technical report). Air Ministry. 1951. Routledge, N.W. (1994). A History of the Royal Regiment of Artillery Anti-Aircraft Artillery, 1914-55. Brassey's. ISBN 1-85753-099-3. Holmes, Lawrence (24 December 2009). "What's a Micklethwait?". Royal Observer Corps Association. Zimmerman, David (2013). "Information and the Air Defence Revolution, 1917–40". In Goldman, Emily (ed.). Information & Revolutions in Military Affairs. Routledge. ISBN 978-1-136-82779-2. First published in: Zimmerman, David (2004). "Information and the Air Defence Revolution, 1917–40". Journal of Strategic Studies. 27 (2): 370–394. doi:10.1080/0140239042000255968. S2CID 153613073.