The first working submarine appears to have been invented as long ago as 1620 by Cornelius Van Drebbel whose demonstration of his creation on the Thames was recorded by Constantijn Huygens (below). The first manned flight took place under a balloon of the Montgolfier brothers just outside Paris in 1783. Despite 133 years of opportunity though the history of airborne anti-submarine warfare doesn’t really get going until September of 1916 when two aircraft of the Austro-Hungarian Navy sunk a French submarine, not bad considering the Austro-Hungarian Naval Air Service had only formed that August.

Anti-submarine aircraft spend their time hunting something that might not be there. Those of you who’ve read your Clancy will be familiar with the basics of modern Anti-Submarine Warfare (ASW), dipping sonar, bistatic sonobuoys, caterpillar drives and what have you. All of which are mostly irrelevant to this article as bar about four exceptions every submarine sinking by an aircraft took place in WW2 before such things were invented. The contents of the list is also massively skewed by the efforts of the Kreigsmarine who managed to lose 287 U-Boats to aircraft, more than the total number of submarines lost by the Royal, US, and Imperial Japanese Navies combined. [1]

Consequently, no German or Japanese aircraft appear, the former apparently only sinking two submarines from the air, both by Do-17. The Imperial Japanese Army do however deserve a special mention for equipping one of their Aircraft Carriers, the Akitsu Maru,with Kokusai Ki-76 observation aircraft to provide anti-submarine protection for their convoys. On November 15^th, 1944, these may  have spotted the USS Queenfish shortly before she fired the torpedoes which sank the carrier. This more or less finished the IJA’s involvement with anti-submarine warfare (ASW), despite some pioneering research into the use of auto gyros. The Imperial Japanese Navy in the meantime had commissioned the Kyushu Q1W1, probably the first aircraft in the world designed from the outset to find and attack submarines. Featuring either a magnetic anomaly detector or radar set, panoramic cockpit loosely based on that of the Ju-88, and an optional 20mm cannon fit, the 901^st Kokutai claimed to have sunk seven enemy submarines while operating the Lorna. Post war records indicate this is probably over-claiming by at least seven.

It’s worth noting that all kill numbers listed here are at best provisional due to the difficulty of confirming a) if you’ve really sunk a submarine and b) which one it was. It was only as recently as May 2021 that the fate of HMS/M Urge was confirmed when her wreck was found just off Malta remarkably free of damage from Italian fighters, but with a big hole where the bow should be, just like you’d get if you hit a mine. [2]

Around 30 types have been involved in sinking submarines, the third of them in this run-down aren’t necessarily the top scorers but do have a certain je ne c’est pas that lifts them above the rest.

[1] 79, 52, and 128 to all causes respectively.

[2] Malta Sub Dives Sink Conspiracy Theory

Wessex/Lynx/Wasp – Joint placing for the only aircraft to sink a submarine post-WW2.

Only one submarine has been sunk by aircraft since the end of World War 2. This unfortunate vessel was the ARA Santa Fe, whose origin as the USS Catfish in 1944 means no post-war submarine has been sunk by enemy action. [3]

On the morning of 25 April 1982, the Santa Fe was departing Grytviken in South Georgia, having landed supplies for the Argentinian forces occupying the island. The captain planned to hide in deep water off the coast before returning that night to an isolated bay to fully recharge the vessel’s batteries for the journey back to the mainland. Unfortunately for the Santa Fe she was detected on radar by the Wessex HAS3 from HMS Antrim before she was in an area to submerge. Approaching from the stern the Wessex was almost overhead before the crew saw it, moments later two depth charges fell towards the submarine. The damage from this first strike was sufficient to prevent the Santa Fe diving, if only because it was unlikely she’d ever surface if she did.

A running battle would now ensue as the Argentinians attempted to return to Grytviken while the Lynx from HMS Brilliant made strafing runs and Wasps from HMS Endurance and Plymouth fired multiple AS.12 missiles. Although the Santa Fe managed to return to the dock her war was over, and she remained there until 1985 when she was towed out to sea and scuttled.

At a stroke the Argentine active submarine force had been reduced by half, which in percentage terms places the Wessex, Lynx, Wasp combination in first place for effect on an enemy force. Meanwhile the ARA’s other active submarine, the San Luis, spent most of the conflict loitering around East Falkland as the most advanced ASW force in NATO failed to pick it out from the myriad wrecks in the area. Which is why the Sea King isn’t on this list.

[3] The North Koreans appear to have lost a submarine to a fishing boat in 1998. It probably wasn’t deliberate.

Lohner L – First aircraft to sink a submarine

Someone has to be first, and despite what the RAF Museum’s website may say, in the case of airborne ASW it wasn’t the UK. Confusingly it was the Austro-Hungarian Navy. Despite now being two medium sized land-locked European countries in 1914 their combined empire included most of what is now Yugoslavia Slovenia, Bosnia, and Croatia. Which gave them an extensive Adriatic coast. As such they had a substantial navy with 13 battleships, 18 destroyers, 6 submarines, an Air Service, and one Lt von Trapp who’d later gain fame for escaping Nazi Austria with a singing nun. [4]

On 15 September 1916 the French Navy’s Foucault was patrolling near the entrance to the naval base at Cattaro (now Kotor in Montenegro). Enter two Lohner L flying boats of the Austro-Hungarian Naval Air Service, which despite in many ways looking like what would happen if an engineer took the phrase ‘flying boat’ literally and just added a couple of wings to a rowing skiff, could carry a few hundred kg of bombs at ‘speeds’ of 57 knots. Although submerged the clear waters of the Adriatic allowed the crew of the two aircraft to spot the Foucault easily and, presumably after checking it wasn’t one of their submarines, attack it. Four bombs were dropped at least one hitting the submarine causing it to lose power and start sinking. Realising they’d broken the first rule of submarining, [5] and with a fire adding to their woes the French somehow managed to get to the surface. Facing an untenable situation, the Captain ordered the powerless submarine scuttled. To add insult to injury the crew were then rescued by their attackers who landed on the water to look after them until a torpedo boat could come to take them into captivity.

Almost definitely the slowest aircraft on this list the Lohner L does have the distinction of proving aircraft have a part to play in sinking submarines.

[4] Not totally relevant but he also married the granddaughter of the inventor of the torpedo.

[5] Don’t let water into the people tank.

Potez-CAMS 141

Although a relatively obscure type the Potez-CAMS 141 has the highest ratio of submarines sunk per airframes built of all time. Admittedly this is because only one of them was built, but it did at least manage to sink U-105 on 2 June 1943.

The Potez-CAMS 141, also known as the Antarès, was designed and built to a 1935 French Admiralty specification for a long-range maritime reconnaissance flying boat. Essentially a gallic Sunderland, Saint-Nazaire if you will. Oddly for a French inter-war aircraft it was very nearly aesthetically pleasing. Really only marred by the placing of a conservatory on either side of the fuselage just aft of the cockpit, presumably so the crew had somewhere to smoke Gauloises and discuss Sartre during long sorties.

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With the prototype flying in 1938 the programme showed the kind of urgency that the Tempest project manager has nightmares about with orders for an additional 19 airframes being placed by September 1939. However, with the factory coming under new management in June of 1940 no further airframes were actually completed. The sole example led a somewhat nomadic existence initially operating out of Morocco, by September of 1940 it was patrolling from Dakar as part of the Vichy French forces. With the Allied landings in North Africa in late 1942 the Antares changed sides again, paving the way for its successful prosecution of the U-105 just south of Dakar seven months later.

Alas being from a production batch of one and with few spares available by the beginning of 1944 she was nearing the end of her operational life, having flown around 1800 hours. Disappointingly the airframe appears to have been scrapped in Africa meaning there are few if any remains of what by at least one measure was the most successful anti-submarine aircraft of all time.

Curtiss H-12 – Responsible for both U-boats sunk by the RNAS.

The Royal Navy tried a variety of tactics to counter U-Boats during the First World War, before grudgingly accepting that, despite not being particularly Nelsonian, escorting merchant ships in convoys might be a more effective way of stopping them being sunk than trying to find a submarine to sink. Which to be fair was still a World War quicker than the US Navy took to come round to the idea. Around the same time convoys were being introduced in early 1917 the Admiralty were also receiving the first examples of the aircraft that would allow it to attack U-Boats from the air. The Curtiss H-12. These started a long tradition of the UK buying an American aircraft and improving it by changing the engine, think Mustang with the Merlin, think Boeing 707 with Conways, think Phantom with err… Speys? In the case of the H-12 the original 160hp Curtiss VX were replaced with Rolls-Royce Eagles with 375hp, more than doubling the installed power. This at least made the H-12, also known as the Large America by the Royal Naval Air Service (RNAS), able to take-off from the water. Something the VX powered versions had difficulty with.

On 27 May 1917 Large America 8656 operating from the Isles of Scilly sighted UC-66 on the surface to the north of the archipelago. The pilot dropped the payload of 100lb bombs two of which seemed to have hit the U-Boat as it soon sank by the stern not to be seen again until 2009. Inconveniently in her dying moments UC-66 had managed to get a few rounds off at 8656, which then flew back to its base on Tresco with the Mechanic holding rags over a resultant leak in the starboard radiator.

At the other end of the English Channel on 22 Sep 1917 H-12 8695, escorted by two Camel fighters, attacked a surfaced submarine in the vicinity of West Hinder Light Vessel, about 20 miles off Ostend. After also being hit by two bombs it was seen to heel over and sink, leaving wreckage and oil on the surface. Initially identified as UC-72, its having been sunk by mines a month earlier rules it out as the actual victim. It’s now thought 8695 sank UB-32.

As an indicator of the effectiveness of the RNAS’ patrols only five merchant ships were sunk when in convoys with a combined air sea escort. Despite the paucity of actual sinkings by aircraft their presence was sufficient to warn off the U-Boats. On top of probably being responsible for 2/3rds of submarines sunk by aircraft in the First World War, Curtiss H-12s were also responsible for shooting down several Zeppelins. Which given its top speed of 87kts must have made for some of the most slowing moving dog-fights in history.

Wildcat

Grumman’s stubby first fighter on a list of submarine killers? What next the Hellcat in the top 10 of mine hunting aircraft? [6]

Although the Wildcat doesn’t appear to be solely responsible for the sinking of any submarines it was involved in the destruction of 27 of them. It kicked this streak off while operating with 802 NAS from HMS Audacity, along with one Lt Winkle Brown. In this case aircraft patrolling from Audacity to intercept German reconnaissance aircraft spotted U-131 on the surface near Madeira and carried out strafing runs while a group of destroyers and sloops closed to deliver the coup de grace with gunfire and depth charges.

More typically, and because it’s not clear you could get enough 0.5” ammunition into a Martlet for it to sink a submarine on its own they were more normally paired with either a Swordfish or Avenger. The vast majority of their assisted kills being while operating from the decks of a USN Escort Carrier alongside its Grumman stable mate. The Wildcat carrying out strafing runs while the Avenger positioned for a depth charge or torpedo attack. The torpedoes in question being code named Fido, were the first homing torpedoes and sought out the noise from the submarine’s propellers. Although a technical marvel it suffered slightly from having a top speed of 15 knots, slightly slower than the surfaced speed of most U-boats. The continual harassment from the Wildcat playing no small part in slowing them down or causing them to dive at which point they struggled to make 8 knots and became easy prey for Fido.

The Wildcat then wasn’t an out and out submarine killer, but it would happily kick them in the gentleman’s parts before its bigger friends delivered the knock-out blow. Like Mini-Me to the Avenger’s Dr Evil.

[6] Yes, yes it is. Didn’t attack many submarines though.

Swordfish

Confusingly for the layperson the main aim of anti-submarine warfare isn’t necessarily sinking submarines. Although it’s always nice if you can. The primary goal is generally to stop the submarine sinking your ships. This is especially true if your ships are carrying supplies that are keeping the country alive. So during the Battle of the Atlantic escorts that managed to sink five U-boats while their convoy was decimated could be viewed less favourably than ones who managed to bring their charges across without loss to either side. This was an area where aircraft could excel merely by flying around and causing the submarine to remain submerged for fear of being spotted. Unlike modern nuclear-powered vessels, which are faster submerged than on the surface, the diesel-electric craft of the first half of the 20^th century were much slower underwater. A typical U-boat could manage 17 knots surfaced but only around 7 knots submerged, and then only for a limited time 5 knots being more sustainable. With a typical convoy progressing at around 10 knots, it became impossible for the submarine to catch its prey while underwater unless it was inside an area in its path the extents of which are known as the Limiting Lines of Approach (LLA). These also apply to nuclear powered submarines although in their case the limit is defined by the speed above which the propellers start to cavitate and create enough noise for Evelyn Glennie to detect them while headlining Wembley.

With this in mind Fairey’s better contribution to the art of naval warfare deserves a special place on this list. In total the Swordfish is credited with 25 submarine kills, which places it 9^th overall on pure numbers. [7] However, its ability to operate not just from Escort Carriers but the even smaller flight decks on Merchant Aircraft Carriers (MACs) enabled them to provide an almost continuous aerial escort across the Atlantic.  MACs were as the name suggests merchant ships with a wooden flight deck just 410’ x 62’ built over the holds, as such they had a limited top speed of around 12kts and carried at most four Swordfish. Despite their limited capability their presence forced the opposition underwater keeping the LLA as favourable as possible. Which goes someway to explaining why in the 207 convoys escorted by Swordfish operating MACs only 9 ships were lost to U-boats despite none having been sunk by the embarked aircraft.

[7] 22 U-boats, 1 Italian sub torpedoed off Libya, 1 Vichy French submarine off Madagascar, and an unfortunate incident with the Free French Submarine Perle.

At 7 knots U1 can’t intercept the merchant ship, after 1 hour she’s in the same position relative to it that U2 was at the beginning of the hour. U2 at 7 knots has meanwhile just fallen further behind the merchant ship.

Sunderland or Catalina

In a world where runways are everywhere it’s easy to forget that before the rapid increase in their numbers during the Second World War water was considered a suitable surface for large aircraft to take-off and land on. Thus, interwar long-distance travel saw the use of the Boeing Clipper and Shorts C-Class Empire flying boat. It’s not surprising then that long-range patrol aircraft would use the same format in the early stages of the war. For ASW the best of these was undoubtedly the Consolidated Catalina. Able to carry out a two-hour patrol at 800 miles from base, two hundred more than the Shorts Sunderland, taking the fight far out into the Atlantic. Despite only having half the engines of the Sunderland the Catalina could carry almost the same weapons load and had the advantage of also being able to use torpedoes, something it used in anger against Japanese shipping around Guadacanal.

In terms of anti-submarine activity, the Catalina sank 40 submarines, 14 more than the Sunderland and equal second overall with the Avenger.

On top of its exploits in the North Atlantic, a Catalina sank two IJN submarines in the Pacific, and for fans of long-range air travel instigated the Double Sunrise service from Ceylon to Western Australia, the usual stop offs in Rangoon and Singapore having issues with take-off and landing rights. The stripped-down aircraft on this service carried three passengers, 152lbs of essential mail, and 1988 gallons of fuel to give it a range of 3600nm for the 3500nm route. Taking between 27 and 33 hours to complete, and with no choice of in-flight movie, this was a test of endurance for both the aircrew and the passengers. Even Ryan Air’s worst flight presumably not having to contend with the threat of being intercepted by the Japanese Air Force over the dark waters of the Indian Ocean.

Wellington

World War II saw the RAF sticking to their pre-war doctrine that strategic bombing would solve everything.  If bombing land locked towns in Germany wasn’t stopping U-boats from attacking convoys, then the answer must be to bomb them harder. This plan didn’t prioritise aircraft for Coastal Command, the defence of merchant shipping apparently being incidental to ensuring the Air Force had the supplies and fuel it needed to wage war. Even by 1941 the best they could hope for were cast offs that Bomber Command didn’t want. Enter the Wellington.

Initially operating a handful of Wellington Mk1Cs with a limited anti-U-boat capability in 1942 the better equipped GR MkVIII became available. As well as the ASV II radar that some Mk1s had had fitted for detecting surfaced submarines it also featured the first use of the Leigh Light a powerful spotlight, and a radar altimeter to allow them to descend safely over the sea at night. After detecting a U-Boat using radar the Wellington would descend to 250’ to make its attack run, as the contact disappeared into the clutter at the bottom of the radar display the Leigh Light would be turned on illuminating the target and allowing the pilot to complete the attack visually. On 4 June 1942 the first such attack was made by a Wellington of 172 Squadron against the Italian submarine Luigi Torelli which was transiting the Bay of Biscay and suddenly found itself lit up like Elvis headlining Vegas. Shortly after that it found itself surrounded by four depth charges. Although the submarine survived the attack it was sufficiently damaged to force a return to port. More was to follow with another three boats forced back to base that June. From being relatively safe waters, the Bay of Biscay now had to be transited submerged, reducing the time that could be spent in the operational areas of the Mid-Atlantic by five days. In July worse was to come for the Kreigsmarine as the first U-boat was sunk by a Wellington as it was returning to France from the Caribbean.

From sinking no U-Boats in the first half of 1942 Coastal Command found itself responsible for 13 and a half in the period from August to December. At a time when ‘Bomber’ Harris was telling Churchill that Coastal Command was ‘merely an obstacle to victory’ this was fortunate indeed. Although the Wellington didn’t have the range to protect convoys in the mid-Atlantic gap, generally managing around 2 hours 500 miles from base, it made the waters around the U-boats’ French bases far more dangerous and pioneered tactics that would be used by Coastal Command to turn the tide in the Battle of the Atlantic from 1943 onwards.

Avenger

While the Swordfish was a good carrier borne ASW aircraft it suffered in a few areas, mainly speed and crew comfort. And contrary to popular opinion it wasn’t as sturdy as you might want when landing on a deck that’s moving up and down by 20 or 30 feet, even if it was easy to repair. If you really wanted to kill submarines while operating off a ship the Grumman Avenger on the other hand suffered none of these issues.

The extra speed not only allowed it to cover a greater search area in a given time, but also meant that during an attack run it would be exposed to the U-boats gunfire for a shorter period. About half in fact. On top of this it made it much easier for other Avengers to make follow up attacks as they’d have a chance to get to the scene of the action before contact with the submarine was lost. Most U-boats being sunk due to a continued aggressive attack rather than a single killer blow. U-118 for instance being attacked with depth charges from 8 Avengers from the USS Bogue before submerging for the final time, which appears to be the record for attacks by a single aircraft type.

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The Grumman Ironworks approach to aircraft construction meanwhile meant the Avenger suffered far less damage during carrier operations. Analysis by the RN not only showed the American aircraft suffered 1/7^th the rate of damage the Swordfish did, but that the lower risk of damage meant carriers were more likely to actually fly them. [8] Which is very much the first stage in detecting a submarine with an aircraft. Having done the analysis, the Fleet Air Arm prioritised its Avengers for anti-submarine warfare, until everyone realised it was better at most things than the Barracuda and they went to the Pacific to be used as bombers.

These advantages, together with being with the convoys the submarines were trying to find, place the Avenger at number two on the all-time list of submarine killing aircraft, with 35 U-boats and at least 5 IJN submarines falling to it.

[8] Directorate of Naval Operational Studies. ‘Achievements of British and US Escort Carriers’. Admiralty, 12 February 1944. ADM 219/95. The National Archives, Kew, United Kingdom.

Liberator

The Kreigsmarine lost 287 U-Boats to aircraft, a quarter of these were lost to the Liberator. Which by all accounts makes it the most submarine killingest aircraft of all time.

The first Liberators delivered to the RAF were considered unsuitable for combat over Europe, Bomber Command therefore magnanimously gave them to Coastal Command who received 20 ex-USAAF B-24As in 1941. These gained the relatively basic ASV Mk II radar, and a less basic semi-retractable pack of four 20mm cannon in the forward bomb bay to attack ships and U-boats with. They could also make a more traditional attack with up to six depth charges while some would receive fittings to carry 60lb rocket projectiles either side of the forward fuselage.

The later Liberator GR Mk III was based on the B-24D as used by Air Forces various, however for the anti-submarine role certain changes were made. The self-sealing liners to the fuel tanks and most of the armour was removed. The turbo-superchargers for the engines that maintained performance at high altitude were deleted, relatively few U-Boats being found above 5,000’. The ventral gun turret was also removed ultimately providing a location for a more advanced centimetric radar. Having undergone the kind of diet that gets you a shot at being the face of Weight Watchers the spare capacity was taken up with over two thousand gallons of fuel and a payload of eight depth charges. As an example of what this allowed on 17 March 1943 a Liberator of 86 Squadron left Aldergrove for an eight-hour fifty-minute flight to join convoy SC122, attacking U-439 on the way causing it to remain submerged for the rest of the day. On reaching SC122 the aircraft came under the orders of the Escort Group Commander and proceeded to sweep the convoy’s route, during which she attacked U-338, again forcing it to submerge. After 11 hours airborne she then returned to base finally landing at Eglinton, short of fuel, 18 hours and 20 minutes after taking off.

In this later Very Long Range (VLR) configuration the Liberator, together with aircraft from Escort Carriers which came into their own around the same time, solved the Mid-Atlantic Gap where U-boats had previously operated without fear of attack from aircraft. The majority of kills were made by aircraft of Coastal Command, however the USAAF’s anti-submarine squadrons were responsible for at least 7 sinkings before they handed over responsibility to the USN’s PB4Y Liberator squadrons. To give some idea of the scale of the Battle of the Atlantic the Liberator was also the second most successful submarine killer in the Pacific. Where it appears to have sunk three IJN submarines.

With endurance, a range of armaments, and able to be modified as new sensors became available the Liberator is the most successful anti-submarine aircraft of all time. Its capabilities again beating housewives’ favourite the B-17 and its paltry 11 sinkings.

Bibliography

A Submariners’ War, The Indian Ocean 1939-45, Michael Wilson

Business in Great Waters, John Terraine

Japanese Anti-Submarine Aircraft in the Pacific War, Ishiguro and Januszewski

https://www.history.navy.mil

The Royal Navy’s Air Service in the Great War, David Hobbs

Uboat.net

Bing Chandler is a former Lynx Observer and current Wildcat Air Safety Officer. If you want a Sea Vixen t-shirt he can fix you up.