In military aviation these days the word ‘legendary’, like so many other statements, is often over-used to describe what are, in reality, fairly run of the military aircraft. My personal opinion is that to even be considered for such an accolade, a reconnaissance aircraft should first meet a number of fairly strict criteria. Firstly, it should have been designed specifically for reconnaissance duties. Secondly, it should have served on the front line for 30+ years and participated in numerous actual operations. Finally, when it entered service it should have had sufficient performance to mark it out as unusual and possibly even unique. In the fairly narrow field of reconnaissance aircraft since WW2, I would only have 5 aircraft on my list, the Lockheed U-2, the Lockheed SR-71, the MiG-25 Foxbat, the McDonnell Douglas RF-4 Phantom and lastly the subject of this article, the English Electric Canberra PR-9.
It’s remarkable to think that the original Canberra first flew way back on 13 May 49, only four years after the end of WW2. But even though the aircraft was originally designed as a medium bomber, it’s performance surpassed many front-line fighter aircraft of the day and it quickly became obvious that the airframe could easily be adapted to create a highly effective reconnaissance platform. Even before the Canberra PR3, a dedicated reconnaissance aircraft, entered service in 1952, 540 Sqn were using a number of specially adapted Canberra B2 medium bombers, equipped with a variety of cameras, to undertake a number of overflights of the Warsaw Pact countries. One 540 Sqn aircraft, WH726, was flown to the USA and fitted with a highly advanced 240” LOROP compact camera mounted in the bomb bay and then conducted a whole series of peripheral border flights along the borders of the Warsaw Pact, known as Operation Robin.
The PR3 had quickly proved the superb capability of a dedicated reconnaissance version of the Canberra. Consequently, the aircraft was subsequently developed into an even more capable version, known as the PR7, and this aircraft gave many years of valuable service in many RAF squadrons, as well as being sold overseas to a number of airforces. Building on the experience gained with the PR3 and PR7, the RAF decided that it wanted a new high-altitude reconnaissance Canberra for strategic reconnaissance. The new Canberra PR9 married the same fuselage used by the PR3 and PR7, with an enlarged wing and more powerful Rolls Royce Avon 206 (RA24) engines. A PR7 (WH793) was modified by Napier to this configuration and served as the prototype for all future PR9s. The bigger wing and powerful engines improved the all ready excellent high altitude performance of the PR7 and the new PR9 soon demonstrated an operational ceiling in excess of 60,000ft. Production PR9s were modified even more and featured a new off-set fighter cockpit based on the Canberra B(1)8, but with a hinged nose section that allowed access for the navigator, who sat in a forward facing ejection seat, in front of and below the pilot. The new off-set canopy, which could be opened on the ground to improve ventilation, was particularly popular with pilots, as it finally addressed one of the weaknesses of the PR3 and PR7 – the poor visibility from the cockpit. However, burying the navigator in the nose was not the ideal solution and in retrospect the Martin B-57 tandem cockpit would have been a much better solution.
English Electric sub-contracted Shorts Brothers in Belfast to build the production aircraft and eventually a total of 23 PR9’s were built between 1958 and 1962. However, only 21 were actually delivered to the RAF, one aircraft (XH129) was written off before it was even delivered and another (XH132) was only used for missile trials. In Jan 1960 the Canberra PR9 entered service with 58 Sqn at RAF Wyton and the first operational sortie was flow three months later. However, the RAF decided that the PR9s would be better deployed to the Mediterranean and 58 Sqn handed over the aircraft to 13 Sqn and then 39 Sqn, both based at RAF Luqa in Malta – 58 Sqn were then re-equipped with the older PR7. Eventually, 13 Sqn were re-equipped with PR7s and returned to RAF Wyton, together with 39 Sqn who by Aug 1976 became the sole operator of the PR9.
By the mid 1970s it was decided to upgrade 12 of the remaining 16 aircraft to enhance their low-level and tactical reconnaissance capability. Between 1976 and 1980 the aircraft were upgraded with a Decca TANS (Tactical Air Navigation System) and improved Doppler as well as a new Sperry Master Reference Gyro. An improved AN/ARI 18228/6 RWR was fitted into the tail unit, resulting in two ‘acorn’ fairings – one on the leading edge of the fin and the other on the tailcone. The withdrawal from service of the expensive and unreliable Phantom reconnaissance pod also allowed the Texas Instruments ARI 5969/3 Infra-Red Line Scan (IRLS) used in the pod to be made available for the PR9 and provision was made for this equipment to be installed in the former flare bay. The flare bay could also carry System III, this was a 36” focal length camera that was derived from the Hycon B camera carried by the U-2R. The System III was a wet film camera fitted with an articulated ‘pointing’ mirror lens unit that could point either vertically down or to three oblique positions either side of the centreline. To obtain the optimum images from the System III, the PR9 had to fly around 50,000ft agl and from this height the camera could produce pin sharp 18 inch prints, with sufficient overlap to allow a stereoscopic image to be created.
Both the IRLS and System III have now been retired, together with the 36” F96 camera that was carried in the forward camera bay. When GPS eventually became available, a Trimble GPS was linked to the TANS and this was later upgraded to a very accurate GPS/INS system to enable the most effective use to be made of the new EO sensor. The new EO sensor is a version of the Senior Year Electro-Optical Relay System (SYERS) that is also carried by the Lockheed U-2S, however, the RAF sensor is known as the Rapid Deployment Electro-Optical System (RADEOS) and is also manufactured by the Goodrich Corporation in the USA.
When a PR9 is tasked for a mission that requires the RADEOS, the bomb-bay doors are removed and the RADEOS, which is mounted on a gimballed crate assembly, is winched up into the flare bay. A pair of deployable 20ft cabins houses the RADEOS ground station and reconnaissance data is either sent direct to the stations via a data link or stored on board until landing. Although the RADEOS produces a very high quality image at long slant range, the image area is quite narrow. To overcome this problem, the PR9 is fitted with a Recon/Optical KA-93 panoramic camera in the forward camera bay; the camera uses a 24” lens to provide high resolution wide angle coverage from the horizon to the vertical either side of the flight path.
It is still a matter of conjecture whether RAF Canberra PR9s were involved in the 1982 Falklands conflict. Some reports have claimed that up to seven PR9s were flown from Wyton to Belize in mid-Apr 82, where they were repainted in Chilean Air Force markings before being flown onto Punta Arenas, the Chilean Air Force base at the extreme end of South America. From Punta Arenas RAF crews allegedly flew the PR9s over mainland Argentina and the South Atlantic, gathering valuable intelligence about the Argentinean forces. It is even rumoured that four of the even older PR7s from 100 Sqn might also have operated from Chile during the conflict. Another unconfirmed rumour is that two RAF Hercules C1s (XV192 and XV292), painted in Chilean Air Force markings, also operated from Punta Arenas during the conflict, presumably to support the RAF detachment; these aircraft were apparently seen after the conflict at RAF Lyneham, still bearing faint traces of Chilean markings. One day the full story of the RAF’s involvement in the Falklands conflict will eventually emerge and until this happens the involvement of the Canberra PR9 and other aircraft just remains conjecture. It is a fact that, after the conflict had ended, the UK government either sold or donated three PR9s to Chile, along with 12 Hawker Hunters – if the aircraft were actually donated, quite why the UK felt that indebted to Chile has never been satisfactorily explained. The Chilean PR9s have now all been retired.
An indication of just how cost-effective the Canberra PR9s have been was given in a parliamentary answer when it was revealed that the total cost of running the five PR9s in FY 20001/2 was only £15.5M. In recent years the aircraft have been used in operations over Afghanistan, Iraq, Bosnia and Somalia and the ability of the RADEOS to interface with the U-2S SYERS ground stations has made the aircraft a particularly valued asset by US commanders and is often right at the top of their ‘wish list’. The problem that the RAF now faces is how to replace such a long-lived and hugely successful aircraft. Originally it was planned to fit the RADEOS in the new Sentinel R1 ASTOR, housed in an extended ventral canoe, however, for various reasons, mainly financial, together with the ever increasing all-up weight of the aircraft, the RADEOS option was deleted. Whilst a dedicated reconnaissance version of the Bombardier Global Express, equipped with the RADEOS and other sensors, would be an idea solution, in the current financial climate it seems highly unlikely that the UK MOD will find sufficient money to fund the purchase and conversion of additional aircraft. Under current plans the remaining five PR9s will finally be retired in 2006. To investigate the various PR9 replacement options, the UK MOD currently have a study underway that is known as Project Dabinett. At present this requirement is ‘aspirational’ and ‘unfunded’ and it is widely recognised that, when the aircraft are no longer available, there will be a ‘capability gap’ and it could well be the end of the decade before this gap is closed – a strange situation for an organisation that recognises the need for increased ISTAR assets, particularly when such aircraft can add additional value to the proposed MOD Network Enabled Capability.
Earlier this year, in co-operation with the US Air Force, the RAF began operating a number of MQ-1/RQ-1 Predators over Iraq in support of UK forces. The benefits of the RAF operating this proven, well developed and advanced Medium Altitude Endurance (MAE) UAV are obvious, but it has recently been reported that the outcome of Project Dabinett will result in the UK not directly replacing the Canberra PR9 on a one-for-one basis. Instead the RAF will rely on current systems for the short term at least. I suspect that the purchase of the Predator and associated support facilities may well have already have happened and that these UAVs will help to plug the gap.
Despite every one of the five remaining 39 Sqn Canberra PR9s being at least 44 years old, thanks to the various upgrades they have undergone over the years, they still offer the UK MOD a unique capability at relatively low cost and are in high demand all around the world. With each passing year, those involved in operating, supporting or just benefiting from the intelligence gathered from the PR9’s sensors have known how difficult these aircraft will be to replace. Whatever the eventual replacement, I very much doubt that it will have either the same capability, longevity or be held in such affection as the venerable Canberra PR9.