The means to undertake

Oboe control roomAs previously discussed, part of the reason for resorting to area bombing was the RAF’s inability to strike specific targets (for an example, look back at the comment about a crew accidentally bombing their own airfield).

Unpredictable weather, fog, heavy cloud and lack of navigation equipment meant aircraft were missing their targets and often getting hopelessly lost trying to reach home, with tragic consequences. Bad weather and navigational errors caused many airmen to be killed and many aircraft destroyed.

Hastings writes that ‘on cloudy nights when the British were bombing blind, the search lights arched upwards, seeking to turn the clouds into a layer of light against which the attackers were silhouetted for the fighters’ (306). Or, as described by the Germans, ‘the enemy bombers crawl across them like like flies on a table cloth’ (Milch 306).

Making gains in this battle demanded significant scientific and technological advances. The following innovations helped turn Bomber Command into a striking force of awesome power that the German High Command were forced to counter with defensive measures involving nearly one million men.

This information is excerpted from Bomber Command’s website:

Preparation for war

In 1936, whilst based at the Air Ministry, Harris successfully argued that Bomber Command would need larger, heavier bombers rather than the existing medium-size aircraft. He foresaw that to have real offensive power the RAF needed aeroplanes that could carry significant bomb loads over great distances.

To cope with the larger aircraft, bigger airfields with longer runways were built and training programmes were organised to produce increasing numbers of skilled aircrews.

The Pathfinders

As part of the effort to improve bombing accuracy, a specialised target-finding force was formed in 1942, made up of generally more experienced crews. The Pathfinders would fly ahead of the main bomber stream and use the most modern technology available to locate and mark the target with coloured flares in order to help less experienced and less well-equipped crews to bomb as accurately as possible.

The role of ‘Master Bomber’ was also developed. An experienced senior pilot would circle the target throughout the raid, giving instructions by radio to approaching bombers as to which part of the target, marked with coloured flares, to aim at. This highly dangerous task was invaluable in maintaining accurate bombing even when the target and markers became obscured by smoke and flames, or when the Germans lit decoy flares away from the correct aiming point.

Navigational technological advances

From 1942 onwards, Bomber Command’s effectiveness was transformed by new heavy bombers including the legendary Lancaster and new navigation equipment.


The first major development in navigational technology was ‘GEE’, a system perfected in early 1942. An on-board set received synchronised radio signals transmitted from ground stations in different locations in England. Two signals gave the navigator a ‘fix’ so he could work out his aircraft’s position on the route to the target at any time.

When flying near the ground stations over home territory, GEE’s accuracy was good; At increasing distances, particularly into Germany, accuracy was reduced. However, with a range of about 300 miles, GEE at least ensured that each bomber crew entered enemy territory with reasonable confidence as to their position. After a time, the Germans worked out a way to jam the system. British scientists were forced to develop new GEE systems and frequencies.


Ready for operations in December 1942, ‘OBOE’ proved to be a particularly accurate device, at least for the shorter range targets. Two OBOE ground stations in England sent out radio signals which the bomber carrying the OBOE equipment received and re-transmitted back. The stations monitored the aircraft’s progress: One station guided the aircraft along a predetermined track, the pilot receiving signals when he deviated to port or starboard; the second station measured the aircraft’s ground speed and calculated the correct moment of bomb release. Range was limited to 300 miles and since only one aircraft could be controlled at a time, OBOE was used primarily by Pathfinder Force.

After D-day in June 1944, the advance of the Allies into the continent meant the RAF could move mobile ground stations into France to extend the range of OBOE deep into Nazi Germany.


‘H2S’ became available in January 1943 and was regarded at the time as astonishingly advanced. Kept top-secret for as long as possible, large bulges began appearing under the bellies of some heavy bombers. Inside was a rotating parabolic dish which mapped the ground beneath, even through cloud, onto a screen in the aircraft. The fairly blurred picture on the screen differentiated between dark areas for sea, bright areas for land and very bright for built up areas. It worked best on coastal targets or those with a broad river or lake nearby. At first, the new H2S sets were installed only in Pathfinder aircraft.

The disadvantage of both H2S and OBOE was that, since the sets transmitted a signal, the Germans could identify the aircraft as an enemy. Also, as was feared, it was not long before an aircraft carrying one of the top-secret sets crashed (in Holland) and the Germans could examine the H2S equipment. Within months German fighters had an airborne device for homing in on RAF bombers using H2S. Nevertheless, H2S had a spectacular effect on bombing accuracy.


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