Britain’s Shackleton Radar Plane Was Born As An Already Antiquated Cold War Dinosaur

The British Royal Air Force announced recently that its forthcoming E-7 Wedgetail airborne early warning and control aircraft will be based at RAF Lossiemouth in Scotland. This is a move that will see the new aircraft operate alongside another 737-derived platform, the Royal Air Force P-8 Poseidon, but it’s also a base with its own unique airborne early warning history. Up until the end of the Cold War, Lossiemouth was home to an extraordinary, almost Rube Goldberg-esque radar plane, the Avro Shackleton AEW2, which ended up defending British airspace for far longer than was reasonable.

The airborne early warning (AEW) version of the Mk 2 variant of the Shackleton maritime patrol aircraft, hence the designation AEW2, only began to be fielded in 1973, a full 24 years after the aircraft had made its first flight. The underlying airframe of all Shackletons traced its DNA all the way back to the Avro Lincoln four-engine bomber, first flown during World War II, and which was itself a further development of the iconic Avro Lancaster heavy bomber. 

A Shackleton AEW2 at RAF Alconbury in 1988., Mike Freer/Wikimedia Commons

The Shackleton inherited the wings and undercarriage of the Lincoln bomber, but got a new, roomier fuselage and replaced the previous Merlin engines with more powerful Griffon engines, driving six-bladed contra-rotating propellers. When the decision was made to use the platform for the aerial early warning role, production of the aircraft had long come to an end, so a dozen Shackleton MR2 maritime patrollers were instead modified for the surveillance role, gaining a “guppy” radome below the forward fuselage. Another three Shackleton MR2 aircraft were prepared to serve as crew trainers, without the radar fitted.

The first iteration of the Shackleton to enter service was the MR1, seen in RAF Coastal Command service in 1953., RuthAS/Wikimedia Commons

The radar inside that radome was the AN/APS-20, which had originally entered U.S. Navy service onboard adapted Grumman Avengers way back in the final months of World War II. The radar and radome both were taken from the Royal Navy’s Gannet AEW3s, carrier-based airborne early warning and control aircraft that had entered service in 1960, but began being withdrawn at the end of that decade after the United Kingdom decided to get rid of its conventional catapult-configured aircraft carriers. 

The Royal Navy Gannet AEW3 was the source of the APS-20 radar used on the Shackleton AEW2., Mike Freer/Wikimedia Commons

While the airborne early warning role was considered vital to the defense of the United Kingdom, the AN/APS-20 was antiquated even when the Shackleton AEW2 entered service and it lacked a height-finding capability. Its performance overall was variable and depended on factors including altitude, weather, sea state, as well as the skills of the operators. Ultimately, the radar had been selected as the cheapest solution, although they were at least rebuilt and updated before being installed in the Shackletons. A number of former Royal Navy Gannet AEW3 radar operators were also transferred to the RAF, to build up skills.

Other equipment on the converted Shackletons included the Orange Harvest broadband electronic countermeasures receiver — a passive detection device originally installed to locate surface ships or submarines — as well the AN/APX-7 identification friend or foe (IFF) interrogator.

A Shackleton AEW2 at RAF Lossiemouth. The radar was mounted directly below the flight deck., Mike Freer/Wikimedia Commons

The crew itself typically comprised of two pilots, two navigators, an engineer, and four radar operators. The way these airmen went about their tasks also had much in common with a previous era, the radar requiring constant “knob-turning,” while grease pencils stood in for computer screens.

One of the first pilots assigned to No 8 Squadron, the Shackleton AEW2 unit, was Bill Howard, who describes the unusual crew composition in Ian Shaw and Sérgio Santana’s Beyond the Horizon, The History of Airborne Early Warning:

The front-end crews were hairy old Coastal Command/maritime types — pilots, flight engineers, and navigators — who would rather have been chasing submarines or doing a rewarding SAR [search and rescue] job, while the rear-end chaps were a mix of Royal Navy/RAF radar operators, sorely piqued at the loss of their beloved aircraft carriers, and who were appalled at the prospect of spending up to 10 hours in a cold, noisy Shackleton. Somehow, however, we managed to get it all together.

A Shackleton AEW2 taxiing for departure from RAF Fairford., Mike Freer/Wikimedia Commons

The primary role of the Shackleton AEW2 was to keep watch over the airspace off the northern coasts of the United Kingdom, where Soviet bombers and maritime patrol aircraft were expected to launch their potential attacks against the country. Since ground-based radars provided only a limited detection capability, especially against low-altitude intruders, the Shackletons were expected to fill the gaps, working alongside RAF interceptors. At the height of operations, the Shackletons were managing the interception of at least six Soviet aircraft per week. In response, a quick reaction alert (QRA) system was set up, under which a Shackleton had to get airborne as rapidly as possible after the first detection of a Soviet aircraft by ground-based radar, or by another NATO asset.

Bill Howard provides the following account of the QRA mission from Lossiemouth:

We held a QRA capability at ‘Lossie’, with a target of getting airborne within two hours after being activated, depending on the day and the time. If it were a normal working day then the response would be much faster. However, if it was a weekend or out of hours, with crew members off base at home, then nearly two hours would be needed. We would be given a target time to arrive ‘on station’ and would aim to arrive at that time, there being no point in arriving too early and wasting fuel while waiting for ‘trade’. Around the UK, we would work with GCI [ground controlled intercept] controllers from RAF Buchan [also in Scotland]. Before going on task we would normally carry out a gentle climb, continuously recording the outside air temperature, looking particularly for evidence of an inversion, which might affect radar performance. Depending on the height of the target, we would plan to operate the barrier at an appropriate level. Normally the expected target would be high level and hence we would aim to be above any inversion layer, flying a racetrack pattern with straight legs of around 40 nautical miles, generally at right angles to the expected target track. The Mk 9 autopilot was pretty basic and a bit fiddly, requiring constant adjustment. Most pilots preferred to hand-fly the aircraft. As long as you trimmed the aircraft well, it was quite responsive to hand flying. We would cruise and operate in the 5,000 to 10,000 feet bracket as the aircraft was unpressurized.

While working alongside RAF, or occasionally other NATO fighters, was a key part of the Shackleton AEW2 mission, the aircraft could not work as a true fighter controller, like a modern airborne early warning and control platform. Instead, the crew provided only advisory guidance to the interceptors, which they communicated with using discreet frequencies on UHF radios.

The antenna of the AN/APS-20 radar., Hammersfan/Wikimedia Commons

Early on in the life of the Shackleton AEW2, it had been planned that the aircraft would also provide protection for Royal Navy operations, which had been deprived of AEW cover after the drawdown of the Gannet AEW3 fleet. However, this proved overly ambitious and the Royal Navy task force that retook the Falkland Islands in 1982 did so without an AEW component, an omission that has been blamed, at least in part, for the heavy losses the British sustained. 

Nicknamed “Growler” by their crews, on account of its thunderous engines, the Shackleton AEW2 provided a less-than-comfortable working environment for the crew, with noise and vibration adding to their fatigue on long missions, which could last up to 12 hours, ranging far out over the North Sea. In fact, some of the previous soundproofing had been removed from the aircraft to save weight. What is more, the power demands of the radar meant the Griffon engines had to be operated much of the time at almost maximum power, making things even noisier.

A Shackleton AEW2 over RAF Mildenhall., Mike Freer/Wikimedia Commons

As well as noisy and cramped working conditions, the Shackleton AEW2 was seriously limited by its performance — with a ceiling of just 20,000 feet, the maximum line-of-sight radar radius was initially around 80 miles, compared to approximately 250 miles for a high-flying jet. In 1973, an airborne moving-target indication mode was added to the radar.

More reminiscent of a World War II-era bomber, the taildragger landing gear was another of the Shackleton AEW2’s anachronisms, as Bill Howard recalled:

The Mk 2 tailwheel ‘Shack’ was a notoriously tricky beast to land for the uninitiated and even the ‘old hands’ were capable of ‘hairy’ landings from time to time. The important thing was to know how to rescue a bad landing, as failure to take timely corrective action could further exacerbate an already unsettling situation. One such incident of a mishandled landing, during a training sortie, resulted in the write-off of one of our two MR2 training ‘hacks’. The fuselage was salvaged, set on concrete plinths, and ingeniously converted into a static crew-training simulator for the navigation/radar crew.

There were plans to replace the Shackleton AEW2 with an airborne early warning and control version of the jet-powered Nimrod maritime patrol aircraft from 1982, but the failure of the Nimrod AEW3 meant the Shackleton had to soldier on for far longer than anticipated. By this time, the Shackleton AEW2 fleet had been reduced by half due to budget cuts. 

A Nimrod AEW3., Mike Freer/Wikimedia Commons

Ultimately, the United Kingdom ordered the E-3D Sentry AWACS to replace the Shackleton AEW2 and finally provide a modern airborne early warning and control capability. The first of the RAF Sentry aircraft arrived at its base of RAF Waddington, Lincolnshire, in 1990 and the Shackleton AEW2 was finally retired in July 1991, Lossiemouth in the process losing its function as an AEW base.

An RAF Sentry AEW1 as night falls on its RAF Waddington base., Crown Copyright

All said, the fact that the piston-engine Shackleton AEW2 was still patrolling the northern approaches to the United Kingdom as late as 1991 is little short of remarkable.

The last airworthy Shackleton was AEW2 serial number WL970, belonging to the Pima Air & Space Museum, Tucson, Arizona., Mike LaChance/Wikimedia Commons

Now, Lossiemouth is set to receive the RAF’s E-7 Wedgetails, also marking the return to the base of No 8 Squadron, the Shackleton AEW2 unit, after an absence of 30 years. While it is currently uncertain if all five of the planned E-7s will ultimately be purchased, you can read all about the background to the Wedgetail deal here.

With this latest development, the Scottish base will once again take on the vital airborne early warning and control role, with the new Boeing Wedgetail jets continuing in the tradition of the “Growler.”  

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