Bomber Stream

The bomber stream was a tactic developed by the Royal Air Force (RAF) Bomber Command to overwhelm the German aerial defences of the Kammhuber Line during World War II.

The Kammhuber Line consisted of three layers of zones of about 32 km long (north–south) and 20 km wide (east–west). In each zone there were two ground-directed night fighters known as "Wild Boar" (Wilde Sau). Initially, RAF Bomber Command sent in their planes individually, with each navigator plotting his own route to the target, to avoid flak concentrations. However this also meant the Himmelbett centres in each cell dealt with only one or two planes at a time, for which the system was designed.

British analysis of the loss of bombers to night fighters of the Kammhuber Line was one of the first applications of statistical analysis which would become known as operational research. The introduction of GEE allowed the RAF bombers to fly by a common route and at the same speed to and from the target, each aircraft being allotted a height band and a time slot in a bomber stream to minimize the risk of collision. Data provided to the British scientists allowed them to calculate that the bomber stream would overwhelm the six potential interceptions per hour that the German night fighters could manage in any one Himmelbett zone. It was, then, a matter of calculating the statistical loss from collisions against the statistical loss from night fighters to calculate how close the bombers should fly to minimise RAF losses.

At the urging of R. V. Jones, Bomber Command reorganized their attacks into streams carefully positioned to fly right down the middle of a cell. The first use of the bomber stream was the first 1,000 bomber raid against Cologne on the night of 30–31 May 1942.

The tactic proved successful and was used until the last days of the war, when centrally-organised German air defences had ceased to exist.