Battle of Britain - RAF Strategy - The Dowding System - Control Systems

Control Systems

Usually the first indications of incoming air raids were received by the Chain Home Radio Direction Finding (RDF) facilities which were located around the coastlines of Great Britain. In most circumstances, RDF could pick up formations of Luftwaffe aircraft as they organised over their own airfields. Once the raiding aircraft moved inland over England, the formations were also plotted by the Observer Corps. The information from RDF and the Observer Corps were sent through to the main operations room of Fighter Command Headquarters at Bentley Priory. The plots were assessed to determine whether they were "hostile" or "friendly". If hostile, the information was sent to the main "operations room", which was in a large underground bunker.

Here the course information of each raid was plotted by WAAFs who received information by a telephone system. Additional intelligence was provided by the "Y" Service radio posts, which monitored enemy radio transmissions, and the "Ultra" decoding centre based at Bletchley Park. Colour coded counters representing each raid were placed on a large table, which had a map of Britain overlaid and squared off with a British Modified Grid. The colour of counter to use for a new sighting was determined by the time of the sighting, the proper colour being indicated by the minute hand of the sector clock. As the plots of the raiding aircraft moved, the counters were pushed across the map by magnetic "rakes". This system enabled the main "Fighter Controller" (usually of squadron leader rank) and Dowding to see quickly where each formation was heading and allowed an estimate to be made of possible targets. The age of the information was readily apparent from the colour of the counter. Because of the simplicity of the system, decisions could be made quickly and easily.

Apart from the controller, most of the room and map information was operated by members of the WAAF. Before the war, there was still a great deal of doubt about the ability of women to stand up to battle conditions, with many airwomen employed on front-line RDF stations and aerodromes. Experience during the battle proved that such doubts were unfounded and the contribution of the WAAFs became essential to the RAF in its control and communications systems and in many other duties.

This information was simultaneously sent to the headquarters of each Group (for example, RAF Uxbridge for 11 Group), where it was "filtered" through a filter room (that is, collated, cross-checked and simplified), before being sent through to another operations room, housed in the Battle of Britain Bunker. Because Group had tactical control of the battle, the operations room was different in layout from the one at Bentley Priory. The main map on the plotting table represented the Group command area and its associated airfields. Extensive radio and telephone equipment transmitted and received a constant flow of information from the various sector airfields as well as the Observer Corps, AA Command and the navy. The "Duty fighter controller" was (for example in 11 Group) Park's personal representative, whose job was to control how and when each raid would be dealt with. He ordered the squadrons airborne and positioned them as he thought best. Timing was of the essence, because "(e)ach minute of unnecessary delay waiting to make absolutely sure that the raid was coming in meant about 2,000 feet of vital altitude our fighters would not have when they met the enemy." (Wing Commander Lord Willoughby de Broke, Senior Fighter Controller, Uxbridge.)

Each Group room had a "tote board" which showed each squadron available to that group. The tote board had a system of lights which enabled the controllers to see the squadron status: Released (not available); Available (airborne in 20 minutes); Readiness (airborne in 5 minutes); Standby (pilots in cockpit, airborne in 2 minutes); Airborne and moving into position; Enemy sighted; Ordered to land; Landed and refuelling/rearming. Next to the tote board, where it could be clearly seen, was a weather board which showed the state of the weather around each airfield. It was the responsibility of the WAAF plotters to continually update the tote and weather boards.

A vital role was played by the telephone engineers of the GPO "who worked all hours repairing communications, installing completely new facilities in the emergency centres, and keeping the nervous system of Fighter Command functioning…" (Air Commodore Eric Roberts, Commander Middle Wallop Sector in 1940)

Despite appearances, the Groups were not mutually supporting; Park, for instance, could only request – not demand – assistance from Brand (who usually co-operated), or from Leigh-Mallory (who often prevaricated). This was because Dowding had never issued standing orders to assist, nor had he created a method to co-ordinate it.

There was a further problem in that the aircraft were not assigned equitably between Groups. While the most effective RAF fighter was the Spitfire, 70% of 11 Group aircraft were Hurricanes. "In total, less than a third of Britain's best fighters were operating in the key sector."