Looking Down the Corridors

by Kevin Wright

  Support Materials

  The most basic requirement for any target is simply to know where it is geographically. The Army PI unit used 1: 25,000 mapping contained in four large books, covering the three Corridors and the BCZ, for this purpose. They preferred 1: 25,000 maps as they were more detailed than the NATO standard 1: 50,000 scale maps. Known targets were hand-drawn onto the individual map sheets as were any new installations and constructions to ensure the mapping was kept up to date; 1: 50,000 maps were gradually adopted because of the decreasing availability, and obsolescence of the 1: 25,000 maps, but they remained in use until the end of the operations. The RAF’s PID used five books of 1: 50,000 mapping, covering the three Corridors, the BCZ and the German Baltic coast, with the RAF’s targets marked on them.

  The US-origin Bombing Encyclopedia, later restyled as the Basic Encyclopedia (BE), recorded all targets worldwide. Each was allocated a unique number, based on its position in a World Area Chart (WAC) area whose boundaries were determined by latitude and longitude co-ordinates. The BE contained a wealth of information, primarily for Air Force planners, to plan attacks on targets and select the optimum weapons systems necessary to neutralise or destroy them. The PIs in Germany mainly used this very accurate location information for their work. The BE’s use and dissemination was initially restricted to the ‘Five Eyes’ community of Australia, Britain, Canada, New Zealand and the USA, which sometimes created difficulties in sharing this material outside that group.

  After several proposals, HQ USAREUR devised a system that was widely adopted. This used the name of the target’s nearest town or village, initially followed by a four-figure number that was replaced in the early 1960s by a three-figure one. The first of the three numbers denoted the ownership or function and the installation, and the last two were the installation’s individual number. For example Schönwalde 281 was a target in or close to Schönwalde belonging to the Soviet ground forces, indicated by the lead number 2, with an individual number of 81.

  Determining the location of photography that had been taken by aircraft was achieved by one of three methods. First the flight’s documentation detailed the cameras and frames used to cover a particular area. For long camera runs covering a number of targets, this was not the most accurate form of record. Second, the photographic coverage card recording all the coverage of a specific target was held in an individual target folder. Finally, the sortie trace plotted all the frames on a transparency that could be laid over a small-scale map to ascertain the areas covered. Indexing of photography is adequate for identifying individual sorties and targets, but successful PIs needed wide-ranging support materials that allowed them not only to refer to historical photographic images but also to compare the historical situation with the current one.

  The main exploitation support tool was the Target Folder and one was created for each installation covered by the reconnaissance programmes, including those at the very edge of their capabilities. Each contained a map extract with the target’s area marked on it and a single photograph, or photographic mosaic, showing the target’s boundaries and any subdivisions. Cards for recording photographic coverage, equipment sightings and parking patterns completed the package. These were all contained in single or multiple A4-size manila wallets, depending on the target’s complexity. Large target complexes had a master target folder containing a map covering the whole area and a photographic mosaic detailing all the installations in the complex. To illustrate the number of target folders involved, the combined Army and RAF target folders occupied ten four-drawer A4-size filing cabinets.

  Other major reference tools were the various service recognition manuals that provided photographs and drawings of equipment used by the Soviet and East German forces. The ground force equipment manuals were organised into equipment roles, such as armour, artillery, engineer, communications and electronics. Similarly the Air Force manuals grouped aircraft and helicopters by function too (fighter, attack, bomber and transport). These official manuals were supplemented by ‘home-made’ recognition materials including the use of stereoscopic pairs of photography.

  The British PI units also had a Photographic Data Index (PDI), which contained ground and air imagery of installations and equipment that had mainly been collected by the AMLMs but included imagery from other sources. The PDI was held in a number of four-drawer card index cabinets.

  Photographic Products

  The Allied Corridor and BCZ programmes produced a number of image formats. The British initially used 8½in × 7½in (216mm × 190mm) followed by 9in × 9in (229mm × 229mm) framing formats and finally the panoramic 5in × 24in (127mm × 610mm) format in the programme’s latter years. The USA used 9in × 9in (229mm × 229mm) and 9in × 18in (229mm × 457mm) framing formats until 1969, when the 5in (127mm) panoramic format replaced them. The 5in produced frames up to 24in (610mm) or 48in (1220mm) long. Between 1953 and 1962 Project Pie Face produced the unique 18in × 36in (457mm × 915mm) format images, known by some PIs as ‘Texas Postcards’. The French used 114mm × 114mm (4.5in × 4.5in) and 55mm × 250mm (2.1in × 9.8in) formats. Individual paper prints were widely used by the Allies until 1969 when the USA introduced continuous roll positive imagery. The British continued using paper prints until 1988 when the introduction of their own panoramic camera installation saw them switch to positive roll film.

  Western light aircraft flights in the BCZ all used 35mm monochrome and colour roll film of up to thirty-six frames. French photographs were received in 5in × 7in (127mm × 178mm) format paper prints.

  Exploitation Priorities and Responsibilities

  RAF Corridor missions were the top priority for British exploitation. The intelligence extracted was rapidly disseminated to the Allies to alert them to any significant items or developments. The next priority was BRIXMIS Chipmunk imagery. Although HQ BRIXMIS in Berlin undertook an initial examination of the material, it was not scrutinised by trained PIs until it got to the PI units at Rheindahlen. US Corridor imagery was the next priority, followed by US and French BCZ imagery. The non-British imagery was exploited as and when it was received, but where possible in chronological order. Exploitation of any other imagery was exploited on a case-by-case basis, depending on the task’s priority.

  When an RAF Corridor flight returned to Wildenrath, the film and crew were taken to Rheindahlen for debriefing by the RAF and Army PI units’ operations officers and relevant members of the Air Staff, especially if there had been a significant incident. During the debriefing, copies of the mission documentation recording the routes and targets imaged were passed to the Heads of the Army and RAF units’ Current Exploitation Sections.

  In the Current Exploitation Sections there was always an air of tension and anticipation when the documentation arrived. This was the first time that the PIs became aware of the mission’s routes and targets. The section heads allocated individual targets to a specific PI for the immediate exploitation phase. From this a signal, detailing the mission highlights, was prepared for the Allied intelligence community. This period was rather like war – 90 per cent waiting for 10 per cent frenetic action. During the wait for the prints’ arrival, there was still much to be done. The target folders relating to the assigned targets were retrieved and the latest information studied. It also helped PIs to know why the target had been selected for coverage. Was there a specific intelligence requirement or was it just routine? Or was it an opportunity target where the aircrew had seen significant activity like a major river crossing or tactical exercise and taken photographs, even though the target had not been formally tasked? Stereoscope lenses were polished, forms prepared. With better preparation came better exploitation – a case of the six ‘Ps’.1

  The PRU processed the film and made two print copies from it, one for each PI unit. After the prints had been subjected to immediate and later deeper exploitation, one copy was retained in the PID film library for twelve months and the second copy was sent by courier to the 497 RTS/RTG as part of the weekly imager
y exchange.

  Once the PIs received their prints it was a case of ‘eyes down, look in’. Would there be any new equipment? Would there be a high level of activity somewhere? Competition between PIs was fierce in the hopes of pulling off a ‘scoop’. Each target was reported on a pre-prepared proforma that already had the mission and target details completed, followed by a blank space to record any highlights. The Section Head collated the completed proformae for inclusion into the First Phase signal, later known as a RECCEXREP to conform to NATO terminology. This signal reported any unusual or high levels of activity including field exercises, river crossings, new equipment sightings and details of any new construction. It also recorded all the targets covered by the mission. The signal was distributed throughout the British, Canadian and US intelligence communities. There was a First Phase signal/RECCEXREP for each individual element of the mission: inbound leg, ‘Chukka’ (BCZ) and outbound leg. Unlike tactical reconnaissance signals of the same name, the First Phase signal/RECCEXREP was not the subject of any rigid time constraints but was transmitted on its completion. It was a matter of professional pride to have these signals transmitted within two hours of receiving the prints. The pace now slowed as the photographic images were subjected to detailed examination that resulted in the consolidated Second Phase report, later known as an Initial Photographic Interpretation Report (IPIR), in NATO terminology.

  These IPIRs reported on all the installations covered, even if there was no apparent military activity. The report included detailed equipment counts by unit area, record any parking patterns, listed shed and bay associations and recorded any unusual or noteworthy activity. It was also disseminated throughout the British, Canadian and US intelligence communities. It provided input to the PI units’ databases, forming the basis for any further analysis. After 1970, PID ceased producing IPIRs by consolidating their month’s exploitation results into a Monthly Summary Report, containing details of all the equipment readouts carried out by them on their targets, together with illustrative imagery. If there was activity, PID would generate a specific individual report to cover this. The UK-produced IPIR was different from the US IPIR, which was subject to more rigid time constraints.

  Production of the IPIR provided some lighter moments. All PIs had their own shorthand that they used to prepare the draft report. Usually the PIs used NAMA to indicate no apparent military activity and NAMA was transcribed in full in the final report by the unit’s typist. One PI reported a target’s status as SFAH and the new typist, not aware of PIs’ foibles, dutifully typed SFAH into the final report. An Intelligence Staff officer enquired, ‘what does SFAH mean?’ A highly embarrassed operations officer explained that it meant that there was a very low level of activity.

  The Chipmunk photography was initially examined at HQ BRIXMIS in Berlin, which produced its version of a First Phase signal recording items of significance. This was sent to HQ BAOR, MoD UK and the other AMLMs. BRIXMIS also generated its own reports, mainly Technical Intelligence Reports, for distribution to the British, Canadian, French and US intelligence communities. After this first look, the photography was sent by courier to PID where it was then made available for detailed exploitation by the PIs; Second Phase exploitation of BRIXMIS imagery was carried out by both PI units to add information to their databases for later analysis and the photography was sometimes used to illustrate Special Studies and Technical Intelligence Reports.

  US Corridor imagery was initially examined and exploited by the 497 RTS/RTG, which produced an IPIR signal containing mission highlights and detailed equipment readouts of the targets covered by the mission. This IPIR conformed to US operating procedures and was disseminated at four-hourly intervals, regardless of whether the mission’s exploitation was complete. Consequently an individual mission’s IPIR could arrive at the British PI units in several parts. The sheer volume and coverage of photography received from the Americans precluded the small British Army PI unit from exploiting it all in detail. The Army operations officer selected targets for detailed exploitation based on the US IPIR’s results. This system was still flexible enough to allow an individual PI to generate a report on their own initiative if they saw something significant. All installations covered by the US missions were recorded on the installation coverage cards to support any future requirements. The Army used US Corridor imagery primarily for database population, but it was also used to support and illustrate special reports. The RAF had fewer targets, so PID was able to fully exploit all relevant US Corridor photography. The smaller scale US photography made it eminently suitable for producing target prints because it could cover a target with a single frame or a small number of frames.

  USCOB and USMLM imagery acquired under Project Lark Spur and imagery from the Forces Français en Berlin (FFB) and MMFL came to the PI units via BRIXMIS and could be up to four weeks old. This often limited its usefulness. The imagery was exploited in its order of arrival and was mainly used for database population and to support other reports.

  To make the optimum use of the limited PI resources and avoid duplication of effort, target types were divided between the two units. The Army’s responsibilities included the organisation and equipment of ground force units; surface-to-surface missile (SSM) units and their associated supply chains; air defence units including man-portable and mobile SAM and anti-aircraft artillery (AAA) units; ground force training areas (including ranges, river-crossing training areas and tactical manoeuvre locations); and static logistic installations such as major repair facilities, military stores, fuel and ammunition depots and new construction sites until their purpose and ownership had been determined.

  The RAF’s responsibilities included Air Order of Battle (AOB) for fixed-wing aircraft and helicopters; air-related infrastructure such as airfields, air-related headquarters and command and control facilities including radar and communications sites; air-related storage and maintenance facilities; and static and semi-mobile SAM and AAA sites to assess how they would affect the planned routes of NATO offensive air operations. It also examined mobile and man-portable SAM systems and mobile AAA systems to assess their capabilities and the threat they posed to British and NATO aircraft and helicopters. The RAF also examined new construction work until its ownership and purpose was established. The two areas of deliberate duplication were some air defence systems and new construction. The Army’s interest was in where the air defence systems fitted into the Ground Force Order of Battle whilst the RAF was mainly concerned about the systems’ technical capabilities and the threats they posed to NATO’s aircraft and helicopters. Both sides took an interest in any new construction outside existing installations until its ownership had been determined, when responsibility was handed over to the relevant service.

  Reporting Responsibilities

  Before 1968 the British Army PI unit’s main reporting responsibility was to provide evidence of any heightened air and ground force posture that could be a precursor to hostilities – Indicators and Warning (I&W). Other reporting priorities were ground force exercises and river crossing training. This was communicated through First and Second Phase reports that consisted of a ‘washing list’ of the equipment present in the target area, regardless of what units were based there. This confirmed the presence of certain equipment at a target but was somewhat imprecise in determining the occupying units. It did not add to knowledge of the unit’s Table of Organisation and Equipment (TO & E) and certainly did not help detect any organisational changes. However, this system was capable of meeting the requirements of the time to provide as much warning as possible of any change in posture that may have preceded an imminent attack. Sightings of new equipment and re-equipment programmes generated many Technical Intelligence Reports that often represented the first time that the equipment had been seen by Western intelligence.

  In the mid 1960s reconnaissance satellites became more reliable and provided wider coverage of the Soviet Union and Warsaw Pact territories without the risks attached to manned o
verflights. This coverage provided more opportunities to detect possible hostile intentions and reduced the importance of I&W information based solely on observations in Germany. Accordingly the reporting emphasis in Germany shifted towards in-depth analysis of units in the target areas. By dividing targets into functional areas and then recording the equipment present in them, the type of unit could be assessed more effectively. These findings could then be compared with the published Order of Battle (ORBAT) to ensure that the ORBAT information was as accurate as possible. This shift to unit analysis required the development of a new set of methodologies and reporting procedures which became the standard procedures for post-1968 target exploitation until the cessation of operations in 1990.

  Technical Intelligence was an important exploitation priority. Although satellite imagery often discovered new equipment at the Soviet Union’s Research and Development (R&D) establishments, it was often only when it entered service in Germany that the Allied intelligence community would acquire close-up images necessary for in-depth analysis. The lower security classification of photographs from Germany, compared to satellite imagery, which had a very limited distribution, eased the dissemination of technical intelligence to a wider audience in the intelligence community.