Every five minutes the WAAFs changed the color of all the enemy counters from yellow to red and then to blue. These colors corresponded to the operations room's clock, which was also color coded (yellow, red and blue) in five-minute increments. This provided a real-time snapshot of a raid in progress and its evolution.
Figure 2: Map Table with Colored Counters Representing Aircraft
When two stations gave the positions of the same aircraft, greater reliance was placed on the accuracy. A colored arrow for each raid was changed as new reports were received. All the information on the table was no older than 15 minutes as the situation was continuously updated. As a result, the model provided a snapshot of real-time events, and this gave the decision-makers the information they needed to manage the movement of their fighters. They could position and group these fighters at the required operational heights to be most effective, which would prove to become a significant advantage.
This information was then disseminated through the complete command structure, which divided the country into six groups (9, 10, 11, 12, 13, 14), based geographically (see Figure 3). Each group had a station and commanding air officer and was further divided into sectors (between 5 to 10) with stations (headquarters), and surrounding, smaller fighter stations/airfields.
Figure 3: RAF Fighter Command hierarchy supporting Bentley Priory
Within the individual group and sector operations centers there were many of the characteristics of Bentley Priory, specifically with the event-tracking and decision-making environment. Bentley Priory, at the center, saw the overall picture of events, whereas group levels saw only what pertained to them. The sector operations centers made up the front line and were expected to have the most activity (see Figure 4).
Figure 4: RAF Fighter Command hierarchy supporting Bentley Priory
The group operations centers could then respond through a second user-interface model: the Tote board. Named after the horse-racing tracks' "Totalisator" board, it had dozens of electric lights that ran the full length of a wall. These indicated the status of squadrons, whether they were in contact with the enemy or disengaging to refuel and rearm on the ground. It also indicated the operational state of readiness of squadrons held in reserve that were "available" in 30 minutes, at "readiness" in five minutes, or at "cockpit readiness" in two minutes to engage in immediate battle. This provided the decision-makers within the elevated gantry (see Figure 1) a means to track the incoming raid and then respond through the tote model. They could determine what resources were available and how they could be deployed. The sector-level operations centers made the final decision, which went out to the individual squadrons and pilots. The operations centers were also linked by telephone to the following commands (see Figure 5) that responded to incoming raids:
- The primary role of the anti-aircraft command, under the army, was to protect the aircraft manufacturing industry and support fighter command. It was divided nationally into seven divisions, but linked to fighter command groups. Anti-aircraft fire was more effective in daylight than at night, as the incoming bomber streams were in closer formations. At night, the aircraft were very widely spaced, with a 1:50 chance of a hit.
- Closely linked to the anti-aircraft command were the searchlight units, which cooperated with each other. Both had to be well aligned to the operational centers, aware of aircraft positions and movement in the skies to avoid firing on friendly fighters by mistake.
- The barrage balloon command operated 52 squadrons across the UK, creating a barrage of large balloons that protected towns and cities, as well as strategic targets like industrial areas and ports. Strung by heavy cables they protected everything at ground level from the threat of low-flying dive-bombers. Set at heights of up to 5,000 feet, they would force aircraft to fly high, limiting their accuracy and bringing them within range of the anti-aircraft guns.
- Closely linked to Bentley Priory were the operational training units that were responsible for pilot training. These units had to be aware of pilot losses, as the number of available pilots was a continual problem for Dowding. Pilot training took three months and was limited to pilots under 30. Dowding brought Allied pilots into the RAF squadrons, as well as volunteers from the Commonwealth and countries under Axis occupation.
- Air-sea rescue operations were directed to downed RAF pilots. Pilots were brought back to squadrons quickly and could be back in the air on the same day.
- Part of the Fighter Supply Chain and under the management of Beaverbrook at the Ministry of Aircraft Production (MAP), the Civilian Repair Operation (CRO) was an important recovery operation. MAP had a very tight relationship with group operations that were in contact with their pilots and knew their positions in the battle, so they could plot the location of downed fighters very quickly.