The Nerves o£ Britain's Air Defence

Evening Post, Volume CXXIX, Issue 35, 10 February 1940, Page 20

The Nerves o£ Britain's Air Defence

#"|"*HE observer corps centimes are # ; the brain of sectors of the A.A.P. #. [Fighter Command, which map jut;the course of every aircraft that lies Lover its territory from information;, reported by observer posts, wrote a special correspondent of the "Manchester Guardian" recently. "Somewhere in the Pennines," I visited one of these posts, which are the nerve-tips of the whole intricate system, and on whose alert efficiency

the:air defence of Britain ultimately depfends. TJie post itself is an earthern igloo perched on top of a moor, with an unobstructed view on all sides. Its circular wall is built chin-high of sandbags, turfed outside, lined with boards and partly roofed' in as a protection against wind and weather. On'a tripod in the centre stands the observer's instrument, and a cupboard let into the wall contains a field telephone connected to the corps centre. On the walls hang aircraft "recognition drawings" showing familiar and "secret" types of British and German machines in silhouette . from various angles. Between instrument and wall there is>just:room for one' careful man to pass another.

Close by'is a small wooden hut containing bunks, telephones, an electrical' cooker and stove, sou-westers, oilskins, overcoats,. and all the multifarious needs of men who keep a lonely vigil in an exposed, deserted spot. All'but the bare fabric of the hut, the sou'westers and oilskins, and one of the telephones has been provided cheerfully, at their own expense, by the volunteer members of the post's crew and their sympathetic friends.

The crew consists of a head observer and twenty men,. mostly: ex-

servicemen, who take three-hour shifts of duty in rotation. Most of them live two miles or more away. At any hour of the day or night there is one man at. the post watching and listening, and another "available" in the hut until a "readiness" call from the centre summons him to the post. The "readiness" call indicates that an aircraft (British or enemy) has been heard or sighted approaching the post, and it is the duty of one

identify it if possible, «and then keep ' tiis- instrument trained on it till it i passes out of sight,, while the other : reads off thrpugh his telephone the i height arid positions indicated •by the I instrument. At night both must i rely Gw -iheir trained hearing to i supply the,necessary information. i This system is a- great deal more I ■reliable-'.than-' misht hp simnosed.'l

partly because the observers have had plenty of practice in judging height, distance, and the direction of sounds, but chiefly because each post is only a unit in a close and thoroughly co-oi'dinated network, with a field of vision overlapped by those of several other posts. The whole area is divided into numbered mile-and-a--quarter squares, and the collation of reports from several posts makes it possible to plot an aircraft's course at the centre so that the next post knows exactly over which square on its instrument table the aircraft will appear. The instrument can indicate the aircraft's height only if its distance is known, and vice versa, but simultaneous reports from two posts make" it possible to fix one factor exactly, and thereby enable the next post to determine the other. From that point onwards the aircraft's position can be followed precisely. So far this post has had no opportunity to prove its skill at the "real thing," but the movements of our own aircraft keep it on the alert, and it does not confine its activities to aircraft observation. Trained to distinguish significant sounds and objects in a familiar environment, its member's report anything unusual which they may see or hear, and their in-. formation is passed on to the police if it seems likely to be useful. They also provide the R.A.F. with weather reports and keep a log of messages, "incidents," and observations. Their Work is interesting at times, tedious for long periods, always important, and potentially vital. Some of' them have been at it for. two years, and all are keen and uncomplaining, though they have learned to welcome with relief the sort of weather that made me glad to leave their high,' bleak moor behind. .