The Mitsubishi A6M "Zero" is a long-range carrier-based fighter aircraft formerly manufactured by Mitsubishi Aircraft Company, a part of Mitsubishi Heavy Industries, and was operated by the Imperial Japanese Navy from 1940 to 1945. The A6M was designated as the Mitsubishi Navy Type 0 carrier fighter (零式艦上戦闘機, rei-shiki-kanjō-sentōki), or the Mitsubishi A6M Rei-sen. The A6M was usually referred to by its pilots as the Reisen (零戦, zero fighter), "0" being the last digit of the imperial year 2600 (1940) when it entered service with the Imperial Navy. The official Allied reporting name was "Zeke", although the name "Zero" (from Type 0) was used colloquially as well.

The Zero is considered to have been the most capable carrier-based fighter in the world when it was introduced early in World War II, combining excellent maneuverability and very long range.[1] The Imperial Japanese Navy Air Service (IJNAS) also frequently used it as a land-based fighter.

In early combat operations, the Zero gained a reputation as a dogfighter,[2] achieving an outstanding kill ratio of 12 to 1,[3] but by mid-1942 a combination of new tactics and the introduction of better equipment enabled Allied pilots to engage the Zero on generally equal terms.[4] By 1943, the Zero was less effective against newer Allied fighters due to design limitations. It lacked hydraulic boosting for its ailerons and rudder, rendering it extremely difficult to maneuver at high speeds. By 1944, with Allied fighters approaching the A6M levels of maneuverability and consistently exceeding its firepower, armor, and speed, the A6M had largely become outdated as a fighter aircraft. However, as design delays and production difficulties hampered the introduction of newer Japanese aircraft models, the Zero continued to serve in a front-line role until the end of the war in the Pacific. During the final phases, it was also adapted for use in kamikaze operations.[5] Japan produced more Zeros than any other model of combat aircraft during the war.

The first Zeros (pre-series of 15 A6M2) went into operation with the 12th Rengo Kōkūtai in July 1940.[13] On 13 September 1940, the Zeros scored their first air-to-air victories when 13 A6M2s led by Lieutenant Saburo Shindo, escorting 27 G3M "Nell" medium-heavy bombers on a raid of Chunking, attacked 34 Soviet-built Polikarpov I-15s and I-16s of the Chinese Nationalist Air Force, claimed "all 27" of the Chinese fighters shot down without loss to themselves, however Major Louie Yim-qun had in fact nursed his I-15 riddled with 48 bullet holes back to base, and Lieutenant Gao Youxin claimed to have shot down one of Lt. Shindo's Zeroes, but at most 4 Zeroes sustained some damage in the 1/2 hour-long dogfight over Chunking.[14][15] By the time they were redeployed a year later, the Zeros had shot down 99 Chinese aircraft[16] (up to 266 according to other sources).[13]

At the time of the attack on Pearl Harbor, 521 Zeros were active in the Pacific, 328 in first-line units.[17] The carrier-borne Model 21 was the type encountered by the Americans. Its tremendous range of over 2,600 kilometres (1,600 mi) allowed it to range farther from its carrier than expected, appearing over distant battlefronts and giving Allied commanders the impression that there were several times as many Zeros as actually existed.[18]

The Zero quickly gained a fearsome reputation.[2] Thanks to a combination of unsurpassed maneuverability – compared to contemporary Axis fighters – and excellent firepower, it easily disposed of Allied aircraft sent against it in the Pacific in 1941.[19][20] It proved a difficult opponent even for the Supermarine Spitfire. "The RAF pilots were trained in methods that were excellent against German and Italian equipment but suicide against the acrobatic Japs", as Lt.Gen. Claire Lee Chennault had to notice.[21] Although not as fast as the British fighter, the Mitsubishi fighter could out-turn the Spitfire with ease, sustain a climb at a very steep angle, and stay in the air for three times as long.[22]

Allied pilots soon developed tactics to cope with the Zero. Due to its extreme agility, engaging a Zero in a traditional, turning dogfight was likely to be fatal.[23] It was better to swoop down from above in a high-speed pass, fire a quick burst, then climb quickly back up to altitude. A short burst of fire from heavy machine guns or cannon was often enough to bring down the fragile Zero. These tactics were regularly employed by Grumman F4F Wildcat fighters during Guadalcanal defense through high-altitude ambush, which was possible due to an early warning system consisting of Coastwatchers and radar.[24] Such "boom-and-zoom" tactics were also successfully used in the China Burma India Theater (CBI) by the "Flying Tigers" of the American Volunteer Group (AVG) against similarly maneuverable Japanese Army aircraft such as the Nakajima Ki-27 "Nate" and Nakajima Ki-43 "Oscar". AVG pilots were trained by their commander Claire Chennault to exploit the advantages of their P-40s, which were very sturdy, heavily armed, generally faster in a dive and level flight at low altitude, with a good rate of roll.[25]

Another important maneuver was Lieutenant Commander John S. "Jimmy" Thach's "Thach Weave", in which two fighters would fly about 60 m (200 ft) apart. If a Zero latched onto the tail of one of the fighters, the two aircraft would turn toward each other. If the Zero followed his original target through the turn, he would come into a position to be fired on by the target's wingman. This tactic was first used to good effect during the Battle of Midway and later over the Solomon Islands.

Many highly experienced Japanese aviators were lost in combat, resulting in a progressive decline in quality, which became a significant factor in Allied successes. Unexpected heavy losses of pilots at the Battles of the Coral Sea and Midway dealt the Japanese carrier air force a blow from which it never fully recovered.[26][27]

19:57

Short film Recognition of the Japanese Zero Fighter (1943), intended to help U.S. airmen quickly distinguish the Zero from friendly aircraft, with Ronald Reagan as pilot Saunders.

Throughout the Battle of Midway Allied pilots expressed a high level of dissatisfaction with the F4F Wildcat. The Commanding Officer of USS Yorktown noted:

The fighter pilots are very disappointed with the performance and length of sustained fire power of the F4F-4 airplanes. The Zero fighters could easily outmaneuver and out-climb the F4F-3, and the consensus of fighter pilot opinion is that the F4F-4 is even more sluggish and slow than the F4F-3. It is also felt that it was a mistake to put 6 guns on the F4F-4 and thus to reduce the rounds per gun. Many of our fighters ran out of ammunition even before the Jap dive bombers arrived over our forces; these were experienced pilots, not novices.[28]

They were astounded by the Zero's superiority:[29]

In the Coral Sea, they made all their approaches from the rear or high side and did relatively little damage because of our armor. It also is desired to call attention to the fact that there was an absence of the fancy stunting during pull outs or approaches for attacks. In this battle, the Japs dove in, made the attack and then immediately pulled out, taking advantage of their superior climb and maneuverability. In attacking fighters, the Zeros usually attacked from above rear at high speed and recovered by climbing vertically until they lost some speed and then pulled on through to complete a small loop of high wing over which placed them out of reach and in position for another attack. By reversing the turn sharply after each attack the leader may get a shot at the enemy while he is climbing away or head on into a scissor if the Jap turns to meet it.[28]

In contrast, Allied fighters were designed with ruggedness and pilot protection in mind.[30] The Japanese ace Saburō Sakai described how the toughness of early Grumman aircraft was a factor in preventing the Zero from attaining total domination:

I had full confidence in my ability to destroy the Grumman and decided to finish off the enemy fighter with only my 7.7 mm machine guns. I turned the 20mm cannon switch to the 'off' position, and closed in. For some strange reason, even after I had poured about five or six hundred rounds of ammunition directly into the Grumman, the airplane did not fall, but kept on flying! I thought this very odd—it had never happened before—and closed the distance between the two airplanes until I could almost reach out and touch the Grumman. To my surprise, the Grumman's rudder and tail were torn to shreds, looking like an old torn piece of rag. With his plane in such condition, no wonder the pilot was unable to continue fighting! A Zero which had taken that many bullets would have been a ball of fire by now.[31]

When the powerfully armed Lockheed P-38 Lightning, armed with four "light barrel" AN/M2 .50 cal. Browning machine guns and one 20 mm autocannon, and the Grumman F6F Hellcat and Vought F4U Corsair, each with six AN/M2 .50 calibre Browning guns, appeared in the Pacific theater, the A6M, with its low-powered engine and lighter armament, was hard-pressed to remain competitive. In combat with an F6F or F4U, the only positive thing that could be said of the Zero at this stage of the war was that, in the hands of a skillful pilot, it could maneuver as well as most of its opponents.[18] Nonetheless, in competent hands, the Zero could still be deadly.

Due to shortages of high-powered aviation engines and problems with planned successor models, namely the superior Mitsubishi A7M2 Reppū, the Zero remained in production until 1945, with over 10,000 of all variants produced.