Oboe (navigation) - Operational History

Operational History

Oboe was first used by Short Stirling heavy bombers in December 1941, attacking Brest.

In December 1942, Oboe on Mosquitos was trialled at Lutterade. Half of the Oboe units malfunctioned in some way. This was about the same time as H2S was introduced. The Germans, observing the curved path of the Mosquito, called the system "Boomerang". The predictable path of the bomber was a vulnerability, compensated for by the fact that the speed and altitude of the Mosquito made it very hard to intercept. The major limitation of Oboe was that it was a line-of-sight system; the curvature of the Earth therefore allowed it to be useful for attacking the Ruhr industrial area, but not targets deeper inside Germany.

Oboe was extremely accurate. In his book, Most Secret War, British physicist R. V. Jones wrote, "As it turned out, Oboe was the most precise bombing system of the whole war. It was so accurate that we had to look into the question of the geodetic alignment of the Ordnance Survey with the Continent, which effectively hinged on triangulation across the straits of Dover." With an error radius of about 110 meters (120 yards) at a range of 400 kilometers (250 mi), Oboe was about as good as optical bombsights. Late in the war it was used for humanitarian purposes to assist food drops to the Dutch still trapped under German occupation, as part of Operation Manna. Drop points were arranged with Dutch Resistance contacts and the food canisters were dropped within about 30 m (100 ft) of the aiming point thanks to Oboe.

It took the Germans more than a year to discover the mystery of the system. Oboe was cracked by engineer H. Widdra (who had already detected the British "Pip Squeak" (IFF) in 1940) at the end of August 1943 at the RF tracking station "Maibaum", located in Kettwig near Essen, while the British bombers attacked the steelworks of "Bochumer Verein".

The Germans tried to jam 1.5 metre / 200 MHz Oboe signals, though by the time they did the British had moved on to the 10 cm / 3 GHz Mk.II Oboe and were using the old transmissions as a ruse. This was discovered in July 1944 after its operator failed to properly mark a drop using the Mk.1 signals.

The Mk.III of April 1944, was more sophisticated. Four aircraft could operate on one frequency and the system could accommodate approaches other than simple radial ones.