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WG486 DHC.1 Chipmunk RAFs Battle of Britain Memorial flight circuit training RAF Coningsby

"Looking down the corridors"

British “spy” flights over east Germany between 1947 and 1990


Between May 1945 and September 1990 the Cold War was fought world-wide between the United States of America (USA) and the Union of Soviet Socialist Republics (USSR). At the end of World War Two, Germany was divided into four occupation zones. They were the American, British and French zones that eventually became West Germany, and the Soviet Zone of East Germany, known as the Deutsche Demokratische Republik (DDR). Berlin lay some 100 miles inside the Soviet Zone and was similarly divided into four city sectors. It was linked to the Western Zones by informally agreed surface routes, three formally agreed air corridors, and the Berlin Control Zone (BCZ).



The Western Allies soon became aware of the burgeoning threat posed by the USSR’s military presence. However, little intelligence gathering could take place in mainland Russia because it was a closed society with an oppressive security regime.

The Western Allies mounted clandestine reconnaissance operations that were some of the most audacious and successful photographic intelligence collection operations of the Cold War. They used their freedom of access to the internationally agreed airspace of the Berlin Air Corridors and BCZ that passed over a large area of East Germany. The operations, disguised as normal training flights, were authorised at the highest political levels and were conducted in great secrecy, using modified transport and training aircraft. The British mounted two programmes, one using aircraft of the Germany-based Royal Air Force (RAF) Communications Squadron to photograph installations under, or near the Corridors and BCZ. This took place once or twice a week. The other utilised the Berlin-based Chipmunk aircraft to photograph installations within the BCZ up to five times a fortnight.

To exploit the products of these flights and convert them into intelligence required trained photographic interpreters (PIs) from both the Army (Intelligence Corps) and the RAF. A PI had to attend and pass the intensive three-month course which, like a driving test, only showed you were basically competent. PIs used equipment, ranging from the simple to the more complex light table to view the images in three-dimensions and extract the maximum intelligence from them.





Army PIs initially came from any part of the Army, but, in 1958, the responsibility was passed to the Intelligence Corps. In Germany, PIs were allocated to the PI unit at the Headquarters British Army of the Rhine. During its lifetime the unit went through many name changes and was responsible for exploiting material from the United States, French, and British. Initially it was in the Georg Wilhelm Haus in Bad Eilsen, but in 1954 it moved to the purpose-built Joint Headquarters building at Rheindahlen, near Mönchen-Gladbach.

Until the arrival of satellite imagery in the mid-1960s, the Corridor and BCZ programmes were the only constant and regular view of Soviet forces available to Western intelligence, and thus they were incredibly valuable. When a new RAF mission arrived, it was quickly scanned for any indications of a surprise Soviet attack and items of significance, such as exercises and new equipment. 

Chipmunk sorties produced very large scale images that enabled the extraction of technical intelligence to help ascertain performance. These flights could be hazardous. For example, on one occasion a Russian soldier with live ammunition shot at the aircraft. This presented a dilemma: on one hand we could protest to the Russians that we had them “banged to rights.” On the other, we would confirm to them exactly what we were up to.

The programmes made many significant contributions to the intelligence picture. This included: forewarning of the 1968 Russian invasion of Czechoslovakia, the increase in the number of guns in artillery batteries from 6 to 8, and the discovery of the SA-9 Gaskin short range air defence system that had never been previously seen, even by satellite coverage.

Whilst it was a very serious business, it was not without its moments of humour. Recording was done manually on to hard copy and each PI developed their own shorthand which would be translated into normal English for the report. However, sometimes things slipped through the net. One day a customer enquired; “what did SFAH mean in a report?” After investigation, he was told that it meant a “very low level of activity”.

Occasionally, PIs and support staff flew to Berlin as part of new crew training. There was no galley on the Pembroke so the sandwiches and tea and coffee flasks were placed in a box marked with the aircraft’s number. On one of these trips there were three Pembrokes in Berlin: ours, the “real” one and a VIP one. One of the junior soldiers collected “our” box and we departed. Once airborne we decided that a coffee was in order. On opening the box we discovered china crockery and sandwiches with the crusts cut off. We checked the box number and it was “ours” so we had been given the VIP contents. Visions of the Berlin catering officer being shown into a room where there was the Mess revolver and bottle of whisky and told to do the Honourable Thing. But no, the VIP was delighted so all was well in the end.


If this has whetted your appetite to know more about these operations, they can be found in “Looking Down The Corridors” available from The History Press.

Zoom microscope viewing table, Medmenham Collection.

Peter Jefferies

Medmenham light table
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