Post war planning
The post war air defence situation
The decrease in pressure on UK air defence from 1943 onwards gave the War Office and Air Ministry planners the opportunity to consider the form of post war air defence. In August 1944 the Chiefs of Staff drew up a draft paper (AIR 8/1445) entitled "Air Defence of Great Britain during the ten years following the defeat of Germany". The paper considered questions of manning levels, what could (and could not) be defended and concluded that it would be essential to maintain a peace time nucleus of ground and air defence that could be expanded within a two year period to full wartime readiness. The paper also stressed the need to continue technical developments and research and to consider countermeasures. The final paper and accompanying report (AIR 2/5773) was issued on 7 July 1945 and was sent to the Prime Minister for approval. The PM declined his approval, stating that this matter had to be considered along with the whole post-war effort, not in isolation. Nevertheless the Chiefs of Staff took this to mean that they could give there own approval to the scheme and it became the basis of Fighter Command planning for the post war period. The "Cherry report" (SD 564) issued at the end of 1945 amplified the scheme's proposals, identified weak points in the system and suggested interim and long term improvements.
Cherry report Criticisms. The main criticism in the "Cherry report" centered on the delays and errors inherent in the reporting system and the difficulties and unreliability of target identification. The delays came about because of the number of communications links in the system and the re-plotting that took place between different levels of command. The situation was further aggravated by the large numbers of radars that were needed to provide the coverage required. The report also noted that IFF Mk III was too imprecise and easily saturated by multiple returns.
Recommendations. Seemingly ignoring the political and financial realities of post-war Britain the wide ranging "Cherry report" made several technical recommendations:
Radar Performance. Whilst a supersonic threat was not considered an immediate threat, high flying aircraft were. Heights of 80,000 and even 100,000 feet were now considered possible and on this basis it was concluded that the time required to achieve interception of a target meant detection at 190 miles would be required for a sea-level target, 260 miles for a target at 30,000 feet and 330 miles for a target at 60,000 feet. Additionally, continuous height information would ideally be required with an accuracy of 100 feet. Improved radar range and angle discrimination was also suggested. There should be as few radar types as possible though alternatives might be required to combat interference and deliberate jamming, and the radars should be static, with mobile equipment available as a stand-by.
I.F.F. (Identification Friend or Foe) The report suggested that I.F.F. should have the same range, discrimination and accuracy as the primary radar and that identification should be available continuously and without delay on:
1. Any aircraft showing no I.F.F. signal or the wrong
signal,
2. Any aircraft with the correct I.F.F. signal,
3. An individual
fighter aircraft on request,
4. An aircraft in distress.
Improved Data Transmission and Display. Displays should constantly show plan position, height, number of targets and identity derived from a number of radars up to 100 miles away. The assembled picture should then be capable of immediate transmission up to 1000 miles. Two types of display were proposed, a Main Type Display or General Situation Map showing total information over the whole area, and an Individual Display under control of the operator. Appropriate Data Transmission systems would be required also.
System Improvements. Four fundamental system principles were proposed:
1. Radar must be deployed to provide cover over the
whole area to be defended
2. There must be unified control and reporting
centres so that data could be collected and acted on without delay. Put another
way, the Filter Room, the Sector Operations Room, GCI stations and AA (Anti-Aircraft)
operations should be merged into a Sector Control and reporting Centre.
3. Identification should be decentralized to the Sector Control and reporting
Centres.
4. Centres should be responsible operationally, technically and
administratively to a parent group in Fighter Command, not to a separate Signals
Group.
The report envisaged a system in which each Sector Control and reporting Centre would be allocated an area of responsibility for track production, for the production and identification of the air picture, and for the broadcast of that air picture data for its Track Production Area (TPA). Similarly, each SC&R would have its own Control Area, similar to but not identical with its TPA, and would scramble and control fighters under the general direction of the Group Operations Room. It was assumed that, with improved radars, the old problem of filtering and sorting plots from several radars would no longer exist, though there might be difficulties of handing over tracks from one TPA to another.
(Most of the information on this page is drawn from "Watching The Skies" - see References for further details on this publication)
