Innocuous they may have looked, but some of the Percival Pembrokes operated by the RAF Germany Communications Squadron and No 60 Squadron had a clandestine Cold War role - one not even known to all members of the unit. Week after week, they plied the air corridors between West Germany and West Berlin, photographing Soviet and East German military targets for vital intelligence purposes. This is the story of Operation "Hallmark"
It was unusual even for the Cold War. Quite a few Squadron members knew that something was going on. Some guessed a little more, but never knew the full story. Those that really knew the details never talked about it. Even over 20 years after the final missions were flown, there is still a reticence among the participants of Operation Hallmark, to talk about the work that they discreetly did for nearly thirty years. Operating from RAF Wildenrath in West Germany, 60 Squadron, with its venerable Percival Pembrokes, led a 'dual life', flying very different types of mission. Some aircraft were configured as 'mild mannered' VIP and communications aircraft shuttling equipment and military personnel around Western Europe. Others led a more clandestine life regularly prowling along the air corridors to and from West Berlin and out to the edge of the Berlin Air Traffic Control Zone, secretly gathering photographic intelligence on high priority Soviet and East German targets. Before reconnaissance satellites became commonplace these almost daily French, US and UK flights were the West's only regular opportunity to gather photographic - and electronic - intelligence on the potential adversaries anywhere. Overflights of Warsaw Pact and Soviet territory were extremely rare, before being halted completely. Kevin Wright had a unique opportunity to talk to some former members of 60 Squadron, and others, to find some details of the missions they flew during the long period of German partition.
The RAF had been undertaking photographic collection flights in the Berlin Air Corridors from 1945 onwards (1), but mostly on an adhoc basis, largely for local tactical purposes and with little direction from London. In 1956 Whitehall became a more active participant in the authorisation process. After the May 1960 downing of Gary Powers U-2, amid increasing tensions over Berlin too, individual corridor flights were then authorised from London at the highest level. A now declassified 'Top Secret' December 1960 request to Prime Minister Harold Macmillan, from Cabinet Secretary Sir Norman Brook, seeks approval for the RAF to undertake two Pembroke photographic flights along the Berlin Air Corridors to "take advantage of a unique opportunity to obtain valuable intelligence on Soviet surface-to-air guided weapons." Two similar flights were also authorised for the RAF Gatow based Chipmunk, available to BRIXMIS, in the Berlin Air Traffic Control Zone. Those flights revealed surface to air missile sites at three separate locations. The flights were apparently well received by the Americans, with whom the British shared that imagery. In London, the Joint Intelligence Committee, assessing the risk of discovery as low, quickly requested authorisation for more flights. Similar requests continued, on a regular basis, through 1961 - especially after the erection of the Berlin Wall in August - when existing intelligence sources begin to dry up. By 1962 they had become regular weekly missions. Though the flights went ahead successfully not everyone in Government was happy about them. Harold Watkinson, then Defence Minister, commented on one early request: "I doubt myself whether the risk is worth taking. Using the corridor for spy flights would be a good card for the Russians." But the flights continued and later regularised with day-to-day authorisation passing to HQ RAF Germany. Although eight Pembrokes had originally been built for photographic use in the Far East all, except XF799, were later disposed of. But under a Contract issued in support of 'Modification 614' work began at the end of 1963 to modify three Pembrokes XL953 and XL954 and the updating of XF799 for photographic work - some of the old Photo Pembrokes that had already been brought back from far East, were flying corridor missions before, using their old camera fit. The contract involved, providing removable fixings for camera installations in the aircraft and associated camera equipment. These Pembrokes became known locally as the 'fit' aircraft. An additional Pembroke - XF796 - flew in the role until 1975, but with a less capable camera equipment fit.
The Pembrokes were configured to carry five cameras mounted in a special frame anchored to the aircraft's floor and ceiling. The 'fit' consisted of three F96 cameras with 12 inch lenses mounted in a 'fan' forward to aft for downward observation. These were protected by sliding hatches on the underside of the fuselage - essential for some element of secrecy and as protection from damage as the Pembroke had very low ground clearance. There were two additional F96 cameras fitted with 48 inch lenses. These looked out of the Pembrokes cabin windows - second from the front on the port side and second from the front on the starboard side. This necessitated the replacement of the standard windows by highly expensive 'quartz' windows to minimize distortion during photography. The cameras were fitted with 500ft film magazines. Given the Pembrokes performance limitations the camera fit represented pretty much a full load for the aircraft. 60 Squadron navigator and later CO, between 1988-90, Squadron Leader Phil Chaney explained: "Around 1980, more modern camera equipment became available to us - similar to that then used on the U-2 to give us true horizon to horizon coverage. The resolution on those cameras were much higher and therefore more susceptible to the effects of vibration." That became a problem on one particular aircraft - XL953. This had constant vibration problems which affected the aircraft's photographic performance. Despite many efforts the problem was never really rectified, though it was ultimately solved in a rather drastic way. "In May 1980, the aircraft was being prepared for deep maintenance at RAF Wildenrath. A static charge ignited some remaining fuel being drained from it. The resulting fire saw the hangar roof damaged and half of XL953 burnt out." The story then goes onto become part of Squadron folklore. Later in the day the new CO, Squadron Leader Andy Spanner was greeted on his return to Wildenrath reportedly with "Boss, good news is we've managed to sort out the vibration problem on '953. Bad news is the aircraft is burnt out."
Flying the Corridor
Then Flight Lieutenant Dave Clark, who had previously flown Pembrokes with 152 Squadron in the Middle East during the mid 1960's, was posted to 60 Squadron for a second tour on the type in May 1975. "I remember on my arrival at Wildenrath, we were shown around an aircraft in the hangar by the boss. Being experienced on the type I noticed all sorts of funny pipes and things on the inside of it, so I asked what they were. The Boss casually said "just ignore it" which I did. I had no idea that we were doing the reconnaissance flights until some months later when I was introduced to the role. The reconnaissance side of the operation was never spoken about. One began to think that something funny was going on because the aircraft 'in the fit' was always parked directly outside the Squadron - on the first slot. Only that aircraft was allowed to park there and with its door always facing the hangar. The curtains were always drawn and it was kept locked." Within 60 Squadron, certainly not all the air and ground crews knew what the 'fit' aircraft and their crews were doing. Phil Chaney, told us: "Knowledge of Operation Hallmark was kept very closely guarded with only a very small number of people on the Station having full knowledge. Essentially, the only people cleared to have access to the contents of the file containing the Operation Hallmark Order were: Station Commander and OC Ops Wing, and those aircrew of 60 Squadron on the list of active flyers."
Crews were generally assigned to flying 'the corridor' for a week, usually flying one round trip during that time, but sometimes two. They would be told on a Monday morning the outline flying plan for the week, matching that with the weather forecasts, as clearly weather was crucial for successful missions. Dave Clark again: "The navigator got the prescribed route from HQ RAFG at Rheindhalen. We would generally take off by about 10.00 and use a standard routing down to the Corridor entrance. Once in the Corridor it was down to the navigator how close you went to the edge of it. We generally flew at 3,500ft, if cloud conditions allowed. One navigator was up front, next to the pilot and the other down the back operating the equipment." Paul Hickley, a 60 Squadron navigator explained their two different roles. "The front-seater was responsible for all of the route navigation, including preparing both the navigation flight plan and the Air Traffic flight plan notification. The rear-seat navigator could not see forwards and so, for vertical shots, had to rely entirely on the front seat navigator (or occasionally the pilot) for information on when to switch the vertical cameras on. However, he did have a vertical sight, a drift-sight, rather like a downward-pointing telescope that could act as a track indicator. If the initial line-up was less than ideal, the navigator could 'talk' the pilot onto the right line once he saw the target. The pilot would then use coarse (indeed, rather agricultural) applications of rudder, whilst trying to keep the wings level, because a gentle turn with bank would have displaced the target from the centre. Most important of all, the front seat navigator was to ensure that the aircraft stayed within the corridors. These only extended 10 miles each side of the centre-line and some of our vertical targets lay very near indeed to the corridor edge."
"We were always advised that we faced the possibility of being shot down if we strayed outside. Most bonafide air traffic in the Berlin Air Corridors hugged the centre-line, as we did ourselves when not on Hallmark missions, because they knew the risks of not doing so. Our job required us to go to the edges, and it concentrated the mind. Watching the Pembrokes on their radars, this would sometimes make the air traffic controllers in the Berlin Air Safety Centre rather nervous until they got the message that the Pembrokes were best left alone to go about their business. Many of the targets were ten to fifteen miles outside the corridors and were perfectly open to photography if the visibility was good enough. The F-96 oblique cameras had a sight-line that could be varied by a manual spring balance adjustment from the horizontal to about fifteen degrees depression angle. If the rear-seater saw the target out of the side windows in good time, he could adjust the camera down to the correct depression angle by visual estimation. Once the camera was in line, he could squint down the barrel (the lens assembly looked like a telescope and filled much of the cabins width) and ask the pilot to make any final adjustment required by a combination of bank and rudder which kept the wing down the right amount but didn't change heading. If he picked it up late, the whole aiming process would have to be done by talking the pilot on to the right angle of bank, because the camera angle motors were quite slow." On approach to RAF Gatow the crew would switch off the equipment and close the curtains. Then land and park up with the door opposite the hangar, so the East German Guards, in the nearby watch towers, could not see into the aircraft door. Outside, crews would also have to be careful in conversation as directional microphones were used by some watchtowers. The pilot would then create a fictitious 'snag' on the aircraft, always something relatively minor, but that would require an air test after 'rectification'. Brian King took up the account: "The airtest generally took place in the afternoon, or perhaps the following day if weather, or planning, required it. The flight would usually necessitate flying around the Berlin Control Zone - particularly close to its edge with the cameras working at around 3,500 feet. Then returning to RAF Gatow to stay overnight." Generally the following day, with the 'fault' cleared, the Pembroke would depart repeating the inbound procedure in reverse. It was standard practice that the flights in and out of Berlin would be flown along different corridors so as to maximise target coverage.
(1) With Avro Ansons until 1959.