The Battle of Britain (8 page)

A report from Bawdsey on August 30, after the annual exercise, noted:

‘Information is to be told to Groups and thence broadcast simultaneously to Sectors:

‘Experience with Biggin Hill has shown that Sectors require information accurately and speedily at a rate of one plot per minute per raid.

‘Information required by the three Groups will be obtained by at least 15 RDF stations, the observers (NB: the people who read the display on the cathode ray tube) at which, in time of high raid density, will tell plots at a high rate. This information is to be filtered and passed accurately and speedily to Groups and Sectors simultaneously. This means that on the average, when stations are all bringing in raids, the Group teller will have to tell information received from 5 RDF stations and will therefore have to tell information at five times the rate of the RDF observers.

‘A Sector requires information accurately and speedily at the rate of one plot per minute per raid. If each Sector can handle even four simultaneous raids, plots must be received at the rate of four per minute.'

No. 11 Gp had six sectors; Nos. 12 and 13 had three each. Hence the Filter Room had to pass plots at the rate of 12 per minute to Nos. 12 and 13 Gps, and 24 per minute to No. 11 if all Sectors were to be able to work to capacity. These were only the plots required by Sectors for interception, but there would also be information on distant approaching raids to tell.

In July 1940 Nos. 12 and 13 Gps each had six Sectors and No. 11 had eight. By the following month, with No. 10 Gp operational, three more Sectors were added. No. 10 in fact had four Sectors, but one of these had formerly been in No. 11, which now was reduced to seven. With four groups totalling 27 Sectors, it is clear why careful selection of radar operators, plotters and filterers was essential.

When the war began, the control and reporting system, the most sophisticated in the world, was fuctioning smoothly. By the time the first sorties in the Battle of Britain were flown, it had reached a degree of efficiency far higher than that of the equivalent German organisation.

The Women's Auxiliary Air Force provided an increasingly large proportion of the personnel employed within it, at radar stations and Filter and Operations Rooms. This body, formed on June 28, 1939, was the successor to the Women's Royal Flying Corps of World War I, which had become the Women's Royal Air Force in 1918 and been disbanded in 1920. When three typists in the early days at Bawdsey had been trained to read and tell the responses on a cathode ray tube, it became apparent that women adapted better in many ways than men to this type of work.

The young women selected to be ‘Clerks, Special Duties', their camouflaged job description, and known less pompously as ‘plotters', had to have a higher than average educational standard. Predominantly, they belonged to the class that their comrades described as ‘boarding school girls'. To the pilots, who were supposed to visit the Ops Room frequently, in order to understand the difficulties of the Controllers' job, they were ‘the beauty chorus' and it was more the sight of a group of attractive girls than duty that drew the young men there.

The Observer Corps was organised in posts and groups. The system was fully tested during the exercise in August 1939. Secrecy about radar was so strict that, although the Corps was under the Air Ministry and received information from the radar chain, only a few officers were allowed to know the details of how this was obtained.

Posts were sited at any convenient place that allowed a good field of view: rooftops were good vantage points. They were not comfortable
places in which to spend several hours at a time. In a small sandbagged enclosure with scant weather protection, equipped with an instrument for estimating height and position of aircraft, binoculars and a telephone, these dedicated men kept watch. Every group HQ had a centre where 12 plotters seated around a map table each received information from two or three posts, thus co-ordinating the efforts of about 30 posts.

Here again, the problem of duplication had to be resolved. A teller passed the plots to a maximum of six Fighter Sectors. An Observer Corps Liaison Officer was on duty at each Fighter Group. At the period with which we are concerned, there were some 30,000 observers, manning more than 1,000 posts radiating from 32 centres.

It was in the Sector Operations Rooms, ‘the sharp end', that direct action against the enemy resulted from this nationwide and complicated network of interlocking data, which converged on the general situation map, the GSM.

An Ops Room had a thick concrete roof and surrounding blast walls. The main floor was some five feet (1.5m) below ground level. The GSM, with plotters wearing head-and-breast sets sitting or standing around it receiving filtered plots, occupied most of the space. With a long rod like a croupier's rake, the plotters moved arrows representing a single aircraft or a formation. A wall clock was divided into five-minute segments successively coloured red, yellow and blue. The arrows forming a track corresponded in colour with the current segment. Thus the Controller could see whether it was fresh or stale. Beside the track was a small block with an identification letter and track number. ‘F' in red on a white ground stood for ‘friendly'. ‘X' in black on a yellow ground meant ‘unidentified'. A black ‘H' on yellow was ‘hostile'. A plot was known as a ‘raid', whether identified as friendly or hostile.

On the first tier of positions overlooking the GSM, running along one side of the large room, sat two NCO deputy controllers. On the next level, stepped slightly back, sat the Controller, a squadron leader in rank: in the early days of the war, this would be a pilot or observer, probably one who had flown in World War I. Gradually, to meet the growing need, non-flying officers were trained in the work. The Controller had two assistants: Ops B, a junior RAF or WAAF officer, and Ops A, usually an airwoman.

There was also a Royal Artillery anti-aircraft liaison officer, who warned anti-aircraft sites when friendly aircraft were near their area and ordered them to cease fire when any entered it and also tried to prevent friendly aircraft being illuminated to the benefit of the enemy.

On the wall facing the Controller's dais were the clock, and the aircraft state boards on which the number of aircraft available in each squadron was shown, with the various states of availability to which the Group Controller had ordered them.

‘Stand-by' meant that the engine had been warmed up and the pilot was strapped into his cockpit, ready to be airborne in two minutes. ‘Readiness' called for pilots to run to their aircraft and take off within five minutes. The average time for a whole squadron to be off the ground was three minutes. The usual states of availability were 30 minutes or an hour, which meant that pilots had to be at their dispersal point on the airfield perimeter, either in the rest hut or, in fine weather, sitting outside it. Sometimes the Group Controller would order 10 or 15 minutes availability, or two hours, when pilots were allowed to be anywhere on the station (in their messes, if they wished). The final state was ‘Released'.

Ops A took instructions from Group – such as ‘One flight of 222 Squadron come to readiness'; ‘64 Squadron to 30 minutes'; ‘56 Squadron released'. He wrote this on a pink form and gave it to the Controller who, having read it, handed it to Ops B, who took action. For example, this might have involved calling the squadron concerned on the telephone and passing on the order.

Behind the Controller's dais were four radio-telephony (R/T) cabins with WAAF, or airmen on listening watch. The transmitter was situated elsewhere within the station, on open ground. The HF receiver was in the cabin and the operator had the often difficult job of tuning it. When, late in the Battle, VHF began to be installed, the receiver was also remote from the cabin and kept tuned on site.

When one of the station's squadrons was ordered to take off – singly, or as one section, or a flight, or the whole 12 – the Controller would speak to the leader on the R/T and tell him what course and height to fly and the enemy's position, height, course and numbers, and all other essential information. He would try to direct the fighter(s) to the best position – up-sun – but usually the individual pilot or leader preferred to make his own tactical decisions. The Controller would continue informing and directing until contact with the enemy was made.

Mention has been made of Biggin Hill in connection with exercises carried out at Bawdsey. In 1936, No. 32 Squadron, stationed at Biggin
Hill and flying Gauntlets, carried out the first exercises with the first embryo Sector Operations Room. It was as a result of these exercises that, with the pilots having the major say, the R/T code was drawn up.

All exchanges on the R/T were logged, so the operators had to write fast and use abbreviations: ‘V' for ‘Vector', ‘A' for ‘Angels', ‘T/H' for ‘Tallyho', a circle with a dot in the centre for ‘Orbit', ‘RULC' for ‘Receiving you loud and clear'. ‘R' stood for ‘Strength'. If a message said, ‘Receiving you strength five', it was logged as ‘RUR5'. ‘Target' was ‘tgt'. ‘Are you receiving me?' became ‘RURM'. ‘Listening out' was ‘L/O', and ‘Over' was ‘O'.

The method of stating figures was also laid down. To avoid confusion, some were given in whole numbers and others in separate digits: Vector in separate digits (eg Vector one-five-zero); Angels in whole numbers (eg ten, fifteen, twenty-two) never in separate digits.

To avoid mishearing through heavy atmospherics or other interference on the R/T, a set pattern was used by controllers. In this way, pilots knew what the first, second, third, etc, parts of a faintly heard message must be about. First, the pilot had to be told his course and height: ‘Vector two-three-five, Angels twenty-one'. Next, where to look. The enemy's relative position was given in clock code, taking 12-o'clock as dead ahead of the pilot: ‘Bandit(s) three-o'clock'. Then, how far away the enemy was: ‘Ten miles'. Then enemy height: ‘Bandit(s) angels thirteen'.

At the end of a message that required no answer, the caller, whether Controller or pilot, said ‘Listening out' or ‘Out'. If an answer were required, the ending was ‘Over to you' or ‘Over'. The ludicrous ‘Over and out' much used in fiction would have been a contradiction. (The acknowledgments ‘Roger', meaning ‘Received', and ‘Wilco' for ‘I will comply', also misused in fiction, were US Air Corps terms adopted by the RAF in 1943 and unknown in the Battle of Britain.)

The TR9D HF transmitter-receivers in aircraft were of poor quality. Their range was rated 35 to 40 miles (56 to 64km) at 15,000ft (4,545m), although in ideal conditions this could be more. The set was vulnerable to all manner of interference, including BBC radio programmes. It had two channels, of which only one was available for voice. Each squadron operated on a different frequency. The second channel was common to all and used for the transmission of a 1,000-cycle note, a shrill whistle, code-named ‘Pipsqueak', which sounded for 14 seconds. One aircraft in each formation was allocated a quadrant of each minute during which its
pipsqueak would come on. While it was transmitting, the voice channel was cut off. The purpose of the device was to fix the position of a single fighter or a formation every minute. With VHF, voice transmissions were used and a good, experienced operator could take an accurate bearing in five seconds.

A sector had three direction-finding (D/F) stations sited at the corners of a triangle about 30 miles (50km) apart, each of which was tied by landline to a position at the fixer table, a much smaller version of the GSM and placed in the Fixer Room, off the main plotting hall. The site of each D/F station on this map table was surrounded by a compass rose marked in 360 degrees. A length of string was anchored at the site. As each station took a bearing on a pipsqueak, it passed it to a plotter who laid off the string along the given bearing. The point at which they intercepted was the fix, the position of the aircraft. A fourth plotter told this through to the GSM, where the fighter's track was duly shown by a fresh arrow. If the cut was precise, it was a first class fix. If the strings formed a small triangle, it was second class and the centre of it was taken as the fix. If they formed a big one, it was known as a ‘cocked hat'.

This was the most useful way of showing the position of friendly fighters because the fix was obtained and plotted within seconds. One of a Controller's most acute problems was that plots that had been through the filtering system were a couple of minutes late by the time he saw them on the GSM. During the interval between being picked up by radar or Observer Corps and plotted at Sector, aircraft had moved several miles and their relative positions might have altered drastically, making interception of a Hostile lengthy or impossible.

Pilots had individual two-figure callsigns, starting at 14 for the squadron commander, which were always given in separate digits. Sectors and squadrons also had callsigns, mostly of two syllables, which were changed from time to time for security. A typical call from the Controller to a single aircraft would be ‘Hello Tomcat One-Four. This is Locust calling. How do you read me?' This would soon be abbreviated to ‘Tomcat One-Four from Locust. D'you read?'

When VHF became general and reception much clearer, with ranges of over 100 miles (160km) at 20,000ft (6,060m) in good conditions, messages became briefer. VHF aircraft sets had four channels with push-button selection. Two were guard frequencies on which a 24-hour listening watch was maintained for aircraft in trouble. Command Guard
was common to all Fighter Command aircraft and Group Guard common to all those in that Group.

The four sections of three aircraft in a squadron were identified by a colour. This had no physical significance such as aircraft markings. ‘A' Flight's sections were Red and Yellow; ‘B' Flight's Blue and Green. When operating in section, flight or squadron strength, pilots' callsigns would be their section colour followed by the number of their position in it. The Leader was ‘One' (eg, ‘Red One'), his right wing man ‘Two', and left winger ‘Three'.