Avro Shackleton: Bombers used to save the environment during an oil spill
In 1971, just off the coast of South Africa, one of the worst environmental disasters at sea shocked the world. Hundreds of thousands of barrels of crude oil-contaminated waters and beaches close to the site before efforts were made to move the stricken ship out of harm's way.
However, in what might be the only recorded case of the use of bombers to save lives, Cold War bombers were used to help stop the developing ecological disaster.
Want to know more? Then join us as we discover the fate of the infamous SS Wafra disaster.
What was the SS Wafra oil spill?
On the 27th of February 1971, the oil tanker SS Wafra ran aground while under tow near Cape Agulhas, South Africa. Cape Agulhas is, in case you are unaware, roughly situated where the Indian and Atlantic Oceans meet.
Laden with hundreds of thousands of barrels of crude oil in her fuel tanks, she quickly floundered. Her hull and fuel tanks were ruptured, and an estimated 200,000 to 470,000 barrels of crude oil leaked into the sea, causing a very serious environmental disaster for the surrounding region.
The SS Wafra had left Saudi Arabia around two weeks earlier in order to deliver her cargo of 472,513 barrels (63,174 tons) of Arabian crude oil to Cape Town, South Africa. She was a single-screw, single-engine steam turbine ship with an empty displacement of around 36,700 tons. Built in Japan, she first entered service as an oil tanker in 1956.
As she rounded the Cape of Good Hope when she suffered a serious engine fault that effectively knocked out her propulsion.
The cause was later discovered to be faulty water feed pipes from the sea to the steam turbines, which ultimately led to the engine room becoming flooded. Adrift at sea with no power, she was taken under tow by a Russian steam tanker called the SS Gdynia.
Initially, the rescue mission went well, but it soon became apparent that the Gdynia lacked the power to tow the oil-laden SS Wafra to her final destination. To this end, another ship, the SS Pongola, took over the job just off the coast of Cape Agulhas.
The journey was going as planned until, incredibly, the tow cable actually failed, leaving the Wafra to her fate. Drifting and still lacking her own power, the SS Wafra grounded on a reef near Cape Agulhas at about 5:30 pm on the 28th of February.
This collision resulted in the rupture of all six of her port cargo tanks and two of the six center tanks, releasing large amounts of crude oil in short order. Of the approximately 26,000 tons of oil that escaped, around six thousand tons washed up at Cape Agulhas.
Beaches from Gansbaai to Cape Agulhas were affected by the slick too, and media of the day reported that the slick was up to 35 miles (56 km) long.
What was the environmental impact of the SS Wafra disaster?
Soon after its beaching, attempts were made to clean up the oil slick, including the use of almost 4,000 US gallons (15,000 liters) of detergent. The detergent was deployed from a mixture of helicopters and specialist marine vessels under the direction of the South African Division of Sea Fisheries.
This was sprayed onto the slick in an effort to break it up and prevent it from washing ashore or harming marine life, but it had little effect.
Dead oiled birds and fish would later litter the beaches of Cape Alghulas and Struisbaai.
The SS Wafra was partially refloated and pulled from the reef in early March by the German salvage tug Oceanic. However, with her hull severely weakened by accident, she quickly began to break apart during the operation, risking the further release of the remaining crude oil in her holds.
In order to reduce the potential environmental impact of the disaster on the shoreline, the larger parts of her hull were towed to a distance of around 200 miles (320 km) out to sea to the edge of the continental shelf. This effort, however, resulted in the formation of a 100-mile (160km) slick in her wake.
With the remainder of the ship now safely out at sea, the next step was to scuttle her to prevent any further environmental damage from the ship. The first attempt involved the use of South African Buccaneer maritime strike aircraft to deal the ship the killing blow.
Despite the use of air-to-ground ordinance, all this attack managed to do was start a series of intense fires on board the stricken ship. These fires burned uncontrollably for several days before a second attempt was made to finish the ship off once and for all.
Where the Buccaneers failed, the Cold War-era descendants of the much more famous Avro Lancaster were brought in to show how this kind of job is done.
Usually tasked with search and rescue missions at this time, a series of Avro Shackletons were armed with depth charges and sent to attack the SS Wafra. Using depth charges, the crews of the bombers were able to finally sink the defiant hulk, preventing further large-scale ecological impacts from the disaster.
Following the Wafra's sinking, the South African Department of Transport quickly realized that despite many Very Large Crude Carriers (VLCCs) using the Cape sea route each year, they were woefully unprepared for another similar incident. Notably, the relevant authorities did not have ocean-going tugs that we're able to assist VLCCs should they get into trouble. What ships they did have, also lacked the necessary equipment to protect sensitive marine areas by breaking up oil spills with chemical dispersants,
In response, they commissioned two new salvage tugs, John Ross and Wolraad Woltemade. These vessels each had 26,200 horsepower (19,500 kW) engines and held the record as the world's largest salvage tugs at the time of delivery.
What was the Avro Shackleton?
Originally developed in the 1940s, the Avro Shackelton was a British long-range maritime patrol aircraft (MPA for short). A refinement of the Avro Lincoln bomber, both these aircraft were the direct descendants of their much more famous ancestor the Avro Lancaster bomber.
This aircraft was conceived from the need, at the time, for a long-range patrol craft to search and destroy potential Soviet maritime threats like submarines. First flown in March of 1949, the prototype "696" was piloted by Chief Test Pilot JH ‘Jimmy’ Orrell.
The prototype Avro "696" Shackleton G.R.1 (VW126) was later re-designated as a Marine Reconnaissance MR.1 and differed from the later production variants in so far as it featured gun turrets and the capability for air-to-air refueling.
Production models incorporated some features of its closely related cousin, the Avro Lincoln, as well as, the Avro Tudor.
The Avro 696 MR.1 featured a chin-mounted search radar and was armed with two 20mm cannons in the nose. Two more cannons were sited in a mid-upper dorsal turret, and it was also armed with twin 0.5in machine guns in the tail.
The Avro 696 was powered by a pair of Rolls-Royce Griffon 57A engines (inboard) and a pair of Rolls-Royce Griffon 57 engines (outboard). After some further testing, the aircraft (now officially dubbed the Shackleton after the polar explorer Sir Ernest Shackleton) officially entered service in the early 1950s.
Production statistics comprised three prototypes, followed by 29 Avro Shackleton MR.1 and 48 Avro 696 Shackleton MR.1A, the latter fitted with four Griffon 57A engines (and wider outboard nacelles).
Initially deployed by the Royal Air Force Coastal Command, its role frequently involved search and rescue missions rather than antisubmarine warfare and picket actions - a role she was well suited to. The aircraft would undergo a series of modifications and variants over its service life, culminating in the Mark 3.
After several years of successful operation, the South African Air Force elected to procure some Mark 3 Shackletons for their own maritime patrol operations, a task they performed well into the mid-1980s.
In all, eight Mark 3 Shackletons were commissioned and built for the South African Air Force.
The Avro Shackleton was eventually replaced by the RAF with the much more capable, jet-powered Hawker Siddeley Nimrod.
During its later life, a small number of the RAF's existing Shackletons received extensive modifications in order to adapt them to perform an airborne early warning (AEW) role. The type continued to be used in this support capacity until 1991 when it was replaced by the Boeing E-3 Sentry AEW aircraft. These were the last examples of the type remaining in active service.
How was the SS Wafra actually sunk?
As we've previously mentioned, it took the might of several Avro Shackleton aircraft to finally put the ship out of its misery. This was done using a series of well-placed depth charges.
However, since depth charges are usually designed to take out submarines, you might be wondering how this was actually possible?
Depth charges (or depth bombs) consist of some form of a canister filled with high explosives. These can be deployed by them rolling off a ship, or, as in the case of the SS Wafra, they can be modified for aerial deployment using parachutes.
For shipborne depth charges, the explosive will typically have a mechanism to detonate at a set depth using a hydrostatic valve. While this is also theoretically possible for aircraft-deployed depth charges, most modern types utilize magnetic contact fuses.
There are even, believe it or not, nuclear depth charges too that have a much greater explosive potential than their chemical explosive siblings. But we digress.
The use of depth charges to take out a surface ship is not unheard of, and they can be quite effective under the right circumstances.
For example, technically speaking, the captured German battleship Ostfriesland, which was sunk by the U.S. Army Air Service’s First Provisional Air Brigade, was led by General William "Billy" Mitchell. The 1921 aerial bombing tests that sunk the ship were a key demonstration of American airpower, which went down due to depth charges. While these were actually more conventional bombs, several of them missed and exploded a few feet away from the battleship's hull.
The resulting explosions punched enormous holes in the side of the ship, eventually sending her to the murky deeps. It is this sort of effect that depth charges are designed to do - detonate in the water column and wreak havoc on any vessel within the blast radius.
Sea mines also do the same thing, except they are usually partially sunken or fixed to the seabed to make navigation of waterways treacherous.
For "true" depth charges to have the best effect, the charges need to detonate a short distance away from the target vessel, and ideally below the hull line. When the charge detonates, it creates a large gas bubble that expands rapidly in an attempt to equalize the pressure of the surrounding water.
This creates a shock wave that lasts until the initial explosive energy is dissipated, and the low-pressure gas bubble rapidly collapses. This expansion and contraction of the water column will cause serious structural damage to any ship close enough to the blast.
In the case of the SS Wafra, since she was already structurally weakened from earlier events, the use of depth charges to hit her below the waterline was deemed sufficient to finally send her to the bottom.
To this end, somewhere in the order of 9 depth, charges were dropped around her hull. These did the job, and she finally sank, with her remaining oil on board, in waters 1.13 miles (1.83km) meters deep. Her wreck remains there to this very day at 36°.57'Sj20°.42'E.
Are there any Avro Shackletons still flying?
According to BAE Systems, a grand total of 181 Avro Shackleton aircraft were built, comprising 3 prototypes, 77 Mark 1s, 59 Mark 2s, 34 Mark 3s, and 8 UK Airborne Early Warning (AEW) variants.
Of these, the vast majority have since been scrapped. However, there are some remaining examples around the world, some of which are still actually airworthy.
Of the individual aircraft that could still, conceivably, take to the air the only real example is SAAF 1722. More commonly known as the "Pelican 22", this aircraft was a Mark 3 variant of the Shackleton that was owned and operated by the South African Air Force.
The "Pelican 22" was one of eight Shackletons operated by the South African Air Force (SAAF) from 1957 to 1984. It was been re-conditioned to flying status and flew as part of the SAAF Historical Flight museum in Cape Town. Although it is technically airworthy, it has more recently been grounded by the Museum for safety and preservation reasons as well as a lack of qualified air and ground crew. Where possible, the engines are run up once a month.
Another Mark 3 Shackleton, "Pelican 16", also operated by the South African Airforce, was restored and deemed airworthy in the mid-1990s. However, this aircraft crash-landed in the Sahara Desert in 1994 while on transit back to the United Kingdom for an appearance at the Fairford Military Air Tattoo that year. No crew or passengers were harmed, but the wreckage still remains in the desert to this day.
Another existing Shackleton is the Mark 2 WR963 (G-SKTN). Currently, in the care of the "Shackleton Preservation Trust", this aircraft is under long-term restoration to flight capability, based at Coventry Airport, England.
Yet another surviving airframe is the Mark 3 WR982, currently on display at the Gatwick Aviation Museum, England. Its engines can be cycled, but the aircraft is not legally airworthy.
Other than that, there are around 16 known examples of surviving Shackletons around the world that are on static display. These are in varying states of repair with some also under active restoration.
The SS Wafra disaster remains one of the worst environmental disasters in living memory. Hundreds of thousands of barrels of oil resulted in serious damage to the local ecosystem and took several years to abate.
Since then, environmental protection agencies and coastal management authorities have seriously beefed up their ability to prevent and tackle disasters as quickly and efficiently as possible. Oil tanker designs have also been overhauled to make them as tough as reasonably practical.
However, until such a time as the need to transport large amounts of liquid oil around the globe are a thing of the past, the next disaster is likely only a matter of time.
While we likely won't be bombing the next wrecked oil tanker in the future, the tale of the SS Wafra is an interesting lesson from history for us all today.