Protecting by warning

The United Kingdom is very vulnerable to nuclear attack. But even if this happened, countless lives could still be saved - provided that the public was given even a few minutes' warning. Further large-scale casualties could also be avoided if information on the pattern and path of any radioactive fall-out could be gathered and broadcast quickly enough.

To meet these two basic requirements, the United Kingdom Warning and Monitoring Organisation (UKWMO) has been developed over recent years. It is a system covering every square mile of the country, and parts of it could continue to function even if other sections were to sustain widespread damage.

UKWMO comes under the direct control of the Home Office. It is no mere concept or blueprint. It exists today as a combination of "concrete, copper wire and trained personnel". Although in "normal" times it is kept ticking over by a skeleton staff, during a national alert or emergency it can be brought into full operation in a matter of hours. At peak strength, it is manned by many thousands of trained personnel, the vast majority of whom are volunteers from all walks of life - including architects, mechanics, farm and factory workers, accountants, civil servants and various other trades and professions.

Links with NATO

In addition to its basic role, UKWMO provides one of Britain's civilian services to NATO. In the event of a nuclear attack, one of its jobs would be to supply information on nuclear bursts and fall-out over the United Kingdom: in return, information from the Continent would be received. The UKWMO structure of communications is fully geared to meet this service.

Time is vital in all these activities. If called into action, the Organisation might be able to give no more than three or four minutes' warning of attack. The effectiveness of these few minutes would depend on people being prepared for an attack and knowing at once what to do. That would be a matter of intensive education in the period immediately preceding hostilities and is a story in itself This booklet describes just how much thought and effort have gone into making the warning system as foolproof as possible.

The Role of UKWMO

The United Kingdom Warning and Monitoring Organisation has five main functions. These are:

1. Warning the public of any air attack.
2. Providing confirmation of nuclear strike.
3. Warning the public of the approach of radioactive fall-out.
4. Supplying the civilian and military authorities in the United Kingdom and neighbouring countries in NATO with details of nuclear bursts and with a scientific assessment of the path and intensity of fall-out
5. Provision of a post-attack meteorological service

Among these activities, warning of air attack is of vital and primary importance. The task or monitoring fall-out, though calling for more resources of men and equipment, is seen essentially as an important adjunct. It is in fact sometimes claimed that UKWO will have justified its existence if it carries out its first and vital function.

Warning against air attack

Information of an impending air attack on the country would come from a number of sources, including North America, NATO, and our own RAF Sector Operations Centres. In the main, however, warning of such attacks would come from the Ballistic Missile Early Warning System at Fylingdales, on the Yorkshire coast, backed up perhaps by further information from other points of the system in Alaska and Greenland.

As for the threat of "back door" nuclear attack from submarines, this too has been taken into account. Special electronic equipment is able to register any nuclear burst the moment it occurs. This equipment is known as AWDREY, an acronym for Atomic Weapon Detection Recognition and Estimation of Yield.

All these reports would be assessed by Home Office staff stationed for the purpose at the United Kingdom Regional Air Operations Centre (UK RAOC). It would he for them to decide from the military advice available whether to set the national warning network in action.

Turning a key in a special electronics box at UK RAUC alerts simultaneously 250 carrier control points (CCPs) located in major police stations throughout the United Kingdom. By pressing a switch on the special communications equipment at each CCP, the police can activate powered sirens sited at strategic locations in urban parts of their warning area. In all, there are some 7,000 power-operated sirens installed throughout the country.

These are backed up by a network of some 11,000 other warning points in rural areas, located mostly at police, fire and coastguard stations, civil and military establishments, hospitals, various industrial centres, and monitoring posts manned by the Royal Observer Corps. Certain warning points are also to be found in shops, pubs and private houses, in areas where suitable locations would not otherwise exist.

Each CCP is linked to the warning points in its area of responsibility by means of a unidirectional carrier line broadcast system, which superimposes additional signals upon the existing Post Office local telephone cable network without interfering with the normal traffic carried on that network. A warning message can be broadcast over this system and heard by the warning point operator on the carrier receiver unit, which resembles a small loudspeaker in appearance.

Upon receiving a warning message of an air attack from its carrier control point over this carrier broadcast system, a warning point operator would sound the alarm by hand-siren. At the same time, warnings would be broadcast at national level on TV sound and radio. Altogether, in the ways described, it is estimated that the vast majority of the population would be alerted in time to take action to protect themselves against the danger.

A simple but effective warning code has been devised as an integral part of the LKWMO system (see Appendix). This code can be easily understood and conveys a sense of great urgency. It covers warnings both against air attack and radioactive fall-out, and gives a subsequent "All Clear" signal.

Monitoring nuclear bursts and fall-out

Special procedures have been built into UKWMO to deal with monitoring nuclear bursts and fall-out - initially to enable fall-out warnings to be assessed and in the longer term to enable a scientific appreciation of the paths and intensities of fall-out to be developed. These procedures are contained within a three-tiered, nationwide structure which absorbs most of the personnel on the strength of the Organisation. First, at field level, is a network of monitoring posts manned by members of the Royal Observer Corps. These are under the control of the second tier, known as Group Controls. In turn, Group Controls report developments in their areas to Sector Controls, which, among other duties, keep the various NATO authorities informed of what is happening over the United Kingdom.

As far as the general public is concerned, the key feature in this structure is the Group Control, for it is at this level that many basic decisions would ho taken - and the intensity and likely behaviour of radioactive fall-out assessed. It is here, too, that warnings of fall-out would originate.

Altogether, there arc 870 monitoring posts up and down the country. Each is responsible for sending information to one of the twenty-five Group Controls. In turn, there are five Sector Controls, four in EngIand and one in Scotland, each with five Group Controls reporting to it. One of these, Western Sector Control, is also responsible for Northern Ireland.

Neighbouring Group Controls are linked by teleprinter, radio and telephone, while each Sector Control is co-located with one of its Group Controls - for example, at Lincoln, in the case of Midland Sector Control, and at Dundee, in the ease of Caledonian.

Apart from the lack of windows, there is nothing very conspicuous about the buildings housing Group and Sector Controls, but each has been purpose-built to withstand a certain amount of blast and give protection against radioactive fall-out. Each has its own stand-by services, including power, sanitation, ventilation and decontamination facilities, as well as emergency food and water supplies.

Overall control of UKWMO is exercised by one of five Sector Controls. Each Sector is capable of functioning as an independent unit and, with full communications between component parts, there is great flexibility in decision-taking if parts of the Organisation were to be destroyed through enemy action.

Meteorological help

Meteorology would play a vital role in the work of UKWMO. The country's entire weather observation and forecasting services would be available to NATO, and these facilities will he vital if the pattern of fall-out over the British Isles and Western Europe is to be predicted and fall-out warnings assessed.

At Sector Control level, three specially trained meteorologists would be stationed at each headquarters to interpret and make predictions from information fed in from the nerve-centre of the Meteorological Office - the £3 million computer installation at Bracknell in Berkshire. Yet even if this was destroyed by enemy action, each Sector Control could continue to draw on data provided through its direct links with the eight Radio Sonde or Upper Air Stations in this country.

UKWMO would also contribute through its network of 870 monitoring posts. Eighty-seven of these have been equipped with meteorological instruments, enabling ROC personnel at these posts to supply basic information to Group Controls, especially on barometric pressure and wind direction. Data of this kind is essential for updating predictions concerning fall-out behaviour.

In this way, UKWMO can be assured of receiving a weather service of one kind or another, as long as the Organisation itself continues to function. It can also provide, during the strike and post-strike phases, a national meteorological service for both civil and military authorities.

Monitoring posts
The front line of fall-out warning

Group Controls may represent the nerve-centres of UKWMO, but the monitoring posts make up the front line at least as far as nuclear activity is concerned.

In time of emergency, these posts would be manned on a round-the-clock basis by personnel of the Royal Observer Corps; in peacetime, members of the Corps inspect their posts and check the equipment on a regular basis and participate in training exercises. The ROC, it should be pointed out, is today an integral part of the UKWMO, though it still enjoys its distinct status and traditions, which go back to the time of the First World War. It has a distinguished record as an aircraft-reporting organisation throughout the Second World War and for some time in the post-war period, before becoming the field force of the UKWMO.

Typical of this chain of posts, sited to cover the whole of the United Kingdom, is one only a few miles from a major city. It lies less than 200 yards from a main road, but is concealed in a thicket of grass and trees. Above ground, the only sign of anything unusual are two objects, one resembling a blue plastic dome and the other a white dustbin. The first is in fact the ionisation chamber of the fixed survey meter for measuring radiation levels. The other encases four pin-hole cameras so arranged that a nuclear burst in any direction from the post would record a mark indicating the bearing and elevation of the burst; it is called a "ground zero indicator".

Some 20 feet below ground is a concrete chamber measuring about 7 X 16 feet by 7 feet in height, which is reached by a ladder running down a concrete shaft. As well as being linked to its carrier control point, it also has communications links to its Group Control. As part of the monitoring equipment, there is an instrument known as a "bomb power indicator'' which records the blast peak over-pressure of an explosion.

It would be the job of each monitoring post to report nuclear burst details to Group Control, beginning with the reading of blast peak over-pressure. Such information should be followed up as soon as possible with details of the elevation and spot size of the burst, recorded by the ground zero indicator.

The fixed survey meter above each post records the intensity of radioactive fall-out. A post would report the arrival of fall-out to its Group Control and thereafter would monitor the intensity of radioactivity, reporting the readings to the Group Control at regular intervals.

As one would expect, monitoring posts have been designed to withstand the effects of blast and fall-out. As in the case of Group and Sector Controls, they have their own source of power independent of the mains supply. They also have sanitation facilities and are equipped with supplies of food and water.

Group Controls in action

The 25 Group Controls may be said to combine the functions of a post office with those of a data processing centre. Their main job is to evaluate reports of nuclear activity sent in by the monitoring posts. From these reports, they would predict how fall-out is likely to develop and originate warnings to the public on its approach. A second key job is to pass on findings and conclusions to other authorities such as Sector Controls, government and local authority wartime headquarters and the Armed Services.

To carry out its tasks, a typical Group Control would require about 50 trained personnel, including some 40 ROC members and a team of warning officers, some of whom are also scientists. It is these warning officers who make the decisions on whom to alert and when warnings should be issued.

Suppose, for example, a nuclear bomb were to explode in the Thames Estuary, data on the burst would he sent in from various monitoring posts in the vicinity to Group Control at Maidstone. Here, using triangulation techniques, it would he determined whether it was an air or ground burst; its power, position and height would also be established.

A number of selected Group Controls have been equipped with electronic AWDREY instrumentation, and information from this equipment can also be used in the triangulation process. AWDREY can detect and record nuclear bursts, no matter how the weapon is delivered.

Warnings of fall-out

Once the triangulation process has been completed, fall-out warnings need to be assessed. Fall-out warnings are based on two kinds of predictions. The first, or initial prediction indicates the outer limit of the area within which fall-out would he contained during the first hour or two after a nuclear burst. It is based on the information relating to the burst computed by the triangulation process, and also on the meteorological forecasts compiled at the Sector Controls, in particular the forecasts of speeds and directions of winds up to 100,000 feet altitude.

The fall-out warning procedure is based on a pattern of warning districts, 750 in all in the United Kingdom, each with art area of about 100 square miles. The warning would originate with a message from a Group Control to carrier control points, whence the warning would be relayed to the various warning points over the carrier line broadcast system. Each of these is equipped with a radiac survey meter for measuring the level of radioactivity and with a maroon for sounding the fall-out warning. If a warning point should find itself isolated, the operator would fire his maroon when the fall-out reached a certain level – 0.3 röntgens per hour.

Subsequently the scientific team would be working on a second type of fall-out prediction: one derived from actual times of fall-out arrival, as observed from ground readings, supported by further meteorological forecasts. Predictions of this type would give a more accurate picture of the probable path of fall-out up to some three hours ahead of its arrival. Meanwhile, ROC personnel in the monitoring posts would be transmitting details of radiation dose-rate readings at regular intervals. These readings would be plotted on graphs, making it possible both to map areas of high radiation risk and to predict later arrivals of fall-out. This information together with the earlier fall-out predictions, would be passed to all the authorities concerned and, via Sector Control, to civil authorities in NATO countries.

Work of the Sector Controls
UKWMO at national level

As with the Group Controls, the job of the five Sector Controls is to provide an instant information service, but at national and international levels - to the Government, the Armed Forces, and NATO headquarters in other countries. Each Sector Control would be capable of doing this, even if the others were destroyed, for each has been designed to function independently.

Specifically, the role of a Sector Control is to co-ordinate the activities of the Group Controls under its responsibility and in particular to control communications within its area. Another key function is to offer high-level scientific advice and generally to ensure that UKWMO's responsibilities are being met.

It is also responsible for liaison with specific countries in the NATO alliance. For example, Midland Sector liases with Denmark, Germany and the Netherlands, while Metropolitan Sector liases with France and Belgium. This is no hollow arrangement included for bureaucratic tidiness. In the event of an emergency, specially trained liaison officers resident in adjacent NATO countries would report to the headquarters of fall-out reporting centres in Western Europe: in the same way, liaison officers would report to Sector Controls in the United Kingdom. These officers would be responsible for sending back to their respective countries information on nuclear bursts and fall-out hazards.

When fully operational, each Sector Control would need a staff or about 80. Among this number would be a scientific team, including a sector scientific adviser, whose job would be "to advise on any unexpected developments" - and a team of meteorologists to provide weather forecasts on which fall-out predictions could be based. These predictions would be frequently updated by new forecasts.

A worthwhile investment

It would be impossible to assess the value of UKWMO in terms of money. Yet the actual cost of maintaining it in full working order comes to a remarkably modest £4.6 million a year. This, for a system that is not only comprehensive, but simple, robust and flexible.

Throughout the development of UKWMO, moreover, much thought has gone into making it as foolproof as possible, into finding an answer for every contingency. In the final analysis, even if the structure of the Organisation was extensively damaged, there still exist what are described as "sufficient alternative means of getting the warning message across." Furthermore, other sections of the Government's emergency control network are concerned with advising the public what to do in the event of attack.

UKWMO is of course only one of a number of services either planned or created by government to go into action in time of national emergency - and each of these has a vital contribution to make. As far as the system described in these pages is concerned, experts have calculated that its contribution could amount to the saving of as many as six to ten million lives - simply by warning enough people in time.

The following types of warning will be given to the public:

Attack warning - RED
Given by siren (rising and falling note); and by BBC broadcast.
Means imminent danger of attack from air.

Fall-out warning - BLACK
Given by maroon, gong or whistle (three bangs or blasts in quick succession).
Means imminent danger of fall-out.

All clear - WHITE
Given by siren (steady note).
Means no further danger.

The fall-out warning will be reinforced by information messages broadcast by local BBC stations wherever possible.

Prepared by the Home Office by the Central Office of Information
Printed in England for Her Magesty's Stationary Office by Daniel Greenaway & Sons Limited.
Dd 803 4436 Pro 13450 8/79

First published 1979

This document is believed to be in the public domain and was transferred to the Internet by George Coney.
Last updated June 1999
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