Free The Battle of Britain by Bickers Richard Townshend Page B

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 BigginHill 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 itspipsqueak 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