Above: detail from a large group photograph of 109 Squadron, an Oboe squadron, at the end of the war. Pathfinder Collection, RAF Wyton.
The Pathfinders used Oboe, the ground-controlled, blind-bombing system, for pin-point accuracy when marking a target even if there was no visibility due to cloud.
Bennett writes in his autobiography Pathfinder:
Oboe was a responder system worked by two stations in this country which sent out radar pulses. [Radar used to be called RDF before the Americans started to improve our language.]* These pulses were received by the aircraft and sent back to the ground station, which then measured the time element in order to ascertain the distance. […]
The first night on which Oboe was used against the enemy was on 20th December 1942, and the pilots were Bufton, Somerville, Griggs, Campbell, O’Neill and Thelwell. Indeed this team was the backbone of the Oboe squadrons from then onwards.
Photo-montage and text below: Pathfinder Collection, RAF Wyton
In most cases, it was an unarmed, high flying Mosquito which used Oboe, its pilot being guided towards the target by dot-dash signals in his headphones and the navigator receiving signals of his own which instructed the very moment when he must release his bright-burning target-indicator flares.
Thus crews in the heavy bombers in their wake would be in no doubt as to the location of the target area and their own aiming point within it.
Such was the precision of Oboe, in which one ground station controlled the aircraft’s track and another gave the release information, that if a crew was judged to be as much as 300 yards off-target, it was back to school again! Time after time the Oboe crews would be “spot on” in positioning their target indicators.
* Comment by John Clifford, one of our Trustees and Senior Curator at the Pathfinder Collection, 14 September 2018:
I must admit I’m amazed at Bennett saying that Oboe was ‘sent out radar pulses’ as it is in fact radio waves/pulses.
RDF (Radio Direction Finder) is a device for finding the direction, or bearing, to a radio source. The act of measuring the direction is known as ‘radio direction finding’ or sometimes simply ‘direction finding’ (DF). Using two or more measurements from different locations, the location of an unknown transmitter can be determined; alternately, using two or more measurements of known transmitters, the location of a vehicle can be determined. RDF is widely used as a radio navigation system, especially with boats and aircraft.
However, saying that, RADAR does stand for Radio Detection and Ranging, so I guess as he says taking on an Americanism, well, I think, in today’s thoughts and engineering that is incorrect-ish, but I do understand . . .