I am better read than most on this subject - although quite possibly less so than Jack, and he also tends to have arcane sources. His statements and mine are not wholly incompatible [tm] :-) All sorts of factors applied. The British developed increasingly useful and accurate "beam" systems, and the Germans in most cases developed countermeasures. Applicable maximum range varied with system and some of the best could not be used over eg Berlin. Oboe, the most accurate , had a maximum radius from the "Cat" station of 300 miles. Even when great technical accuracy was available the number of aircraft which could use it was limited and translating the location of the Master Bomber's possibly pin-point projectile into an accurately dropped overall bombload often proved excessively challenging. As Jack notes. RV Jones previously cited "Most Secret War" - of which the US title is (I now see) "The Wizard War" * provides some good discussion of the various systems and their achievable accuracies. The Pathfinders (which included my late Uncle George Ryder, who got an enforced German holiday part way through proceedings) would probably have claimed that "opposed" was irrelevant (even if not true :-) ). Jones says (non verbatim) " ... Oboe was the most precise bombing system of the whole war ... special permission to ID target in advance to reward Belgian observers ... distances paced out in yards afterwards by underground ... best bomb obtained a direct hit on nightfighter HQ..." All of which shows how bad some of the rest must have been to have obtained Jack's quoted CEP of 5 miles :-). Oboe used two stations in the UK and the aircraft flew in a constant radius arc from one station until it was at a specified distance from a second station so that position was triangulated. He says that the system was so accurate that they looked at aligning the geodetic surveys of Europe and the UK by triangulating across the straits of dover - i n wartime. * Coward MaCann ..., 1978 , ISBN 0-698-10896-5 Wikipedia - http://en.wikipedia.org/wiki/Oboe_(navigation) Annoying but useful video - 14 minutes https://www.youtube.com/watch?v=3DhURdl91MCNQ Some interesting comment http://ww2today.com/9th-january-1943-the-raf-start-blind-bombing-with-oboe *Reverting to Oboe, a very historic occasion was a particular sky-marking raid on Essen. This took place on 9th January 1943. The C.-in-C. detailed a moderate little force of Lancasters to bomb on sky-markers, and all went well. There was complete solid cloud cover below, unlike the better conditions which had prevailed on the other sky-marking raids already carried out.* *Thus it was quite clear to those on the ground that the most valuable target in Germany, Krupps works at Essen, was being hit by a blind bombing method.* *Hitler immediately called a meeting, at which he himself personally took part, and apparently he was most violent in his denial that such a thing was possible. He insisted that there must have been breaks in the cloud so that the R.A.F. could see the targets. His various experts advised him otherwise, but apparently he was furious at the thought.* *All this we discovered after the end of the war, when German records of the meeting became available. Oboe had not only shattered the targets of Germany, but had also shattered German morale, it continued the process for the rest of the war, and was probably the most effective single instrument of warfare in our entire armoury.* Oboe jamming & some good technical explanation German site. Some translated material which they say was first posted here in English. http://www.gyges.dk/jamming_service%20Oboe.htm Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .