Degraded Performance of the Japanese Navy Air Force (JNAF)


Pacific Glory, by Nicolas Trudgian (P-38 Lightning vs Mitsubishi Zero)

By 16 June photographs showed that aircraft at Rabaul had increased to 245; the subsidiary ‘ring’ airfields were also full of planes. There followed the single largest air battle of the entire Solomon Islands Campaign; 120 Japanese aircraft went up against 104 defenders in a dogfight over Savo Island, Tulagi and Cape Esperance. The Allies scored a remarkable one-sided victory with 49 Zeros and 32 dive-bombers, 81 planes in aggregate, downed for the loss of just 6 aircraft. While the Japanese were still able to commit large forces to the battle, the victory on 16 June continued the pattern of an increasingly one-sided battle for air supremacy. From April to early June 1943 the ratio of the Allies’ kills-to-losses averaged about 3:1; on 12 June the Allies scored a 5:1 victory and ten days later the win ratio jumped yet again to 13:1. What was happening?

A 3:1 win:loss ratio for the Allies was already a substantial advantage that spoke volumes about the advances made by Allied equipment as well as the quality of their pilots in the first half of 1943. By comparison at the start of the war Japanese Naval and Military Air Forces had overwhelmed the Allies throughout the Asia-Pacific Region, often winning air battles by ratios of 10:1 or more. In the first half of 1943 the Commander of Air Forces in the Solomons (COMAIRSOL) had already achieved a startling turnaround in performance. From the middle of June 1943 there was another huge leg up in comparative performance of Allied fighter forces. As with Lieutenant-General Kenney’s remarkable victory at the Battle of the Bismarck Sea, it seems that a number of disparate factors had led to a tipping point moment. The gradual erosion of the Guadalcanal Campaign was putting increasing pressure, not so much on the availability of aircraft, but on the availability of trained pilots. It was systematic of the entire structure of the Imperial Japanese General Staff that war was planned as a short-term project with the emphasis on attack. The Japanese Navy, even more than the Imperial Japanese Army, was particularly unprepared for a war of attrition; their psychology, inherited from their great victory at the Battle of Tsushima, was to focus energy and resources on the winning of a single transformative engagement rather than planning for a long war.

The Japanese Navy was not only failing to train enough pilots, it was also failing to protect them. It is instructive to consider that very few US pilots died when their planes were shot down. In part it was because, unlike their Japanese counterparts, US fighters had better armored cockpits. Moreover without self-sealing fuel lines, Japanese Zero frequently blew up when hit by tracer bullets, killing the pilot instantly. When US pilots ditched or parachuted into the sea, the US Navy had a well-organized search and recovery capability. The Japanese Navy did not. Advantageously most of the dogfights in the April–June 1943 period took place closer to US held areas. US pilots were also better conditioned, with rotation and rest and recreation (R&R) built into the whole logistic framework of the various forces operating under COMAIRSOL.

New Japanese fighters also had to face a multiplicity of challenges given the diversity in capability of the six types of Allied fighter planes with which they were likely to engage. By contrast US pilots in the South Pacific only had to develop tactics to combat the Zero. On 28 March 1944, the US Flight Test Engineering Branch concluded after testing a captured Mitsubishi Zero, “The airplane is highly maneuverable, has a fair rate of climb, and good visibility; however, its speed in level flight is low, it is lightly armed, has no armor protection for the pilot, and the fuel tanks are not self sealing. The cockpit layout is fair, leg-room is insufficient for an average sized man …” The Zero had abundant good qualities; it was reliable, had an extraordinarily long range, and was, above all, maneuverable and easy to fly. Even with the swathe of more advanced US fighters now arriving in the South Pacific, it was not wise to get into a prolonged dogfight with a Zero.

Nonetheless, Allied pilots learned to exploit the Zero’s weaknesses. Allied fighters with a superior ‘ceiling’ capability would look to swoop down on a Zero and then skedaddle before the enemy fighter could make his better maneuverability count. By shooting and then diving, US pilots realized that their Japanese counterparts could not follow because of poorer diving speeds. Moreover by working in teams US pilots learned to thwart the Zero’s superior maneuverability in dogfights.

In Tokyo the developing catastrophe in the air was being hidden from senior commanders. Although losses were heavy, Japanese crews were reporting massively inflated results for transport ships sunk and enemy ‘kills’. On 14 April 1943 Yamamoto ordered a two-pronged force, codenamed Y-1 and Y-2, consisting of 75 fighters and 23 dive-bombers from the Third Fleet (Y-1) along with the 11th Air Fleet’s 54 fighters and 44 medium bombers (Y-2), to make a major attack on Milne Bay, which had become an important logistical center for the Allied advance in New Guinea and the Solomons.

Japanese pilots claimed to have shot down forty-four Allied aircraft. In fact Allied losses amounted to a single P-40 and its pilot killed; four others were shot up and a P-38 crash-landed. Similarly exaggerated claims were made for ships sunk. Supposedly four transports had been sunk and six others heavily damaged. The reality was that only one ship was heavily damaged out of the three that received hits. Admiral Ugaki noted happily in his diary, “Today’s operations of Y-1 and Y-2 a great success. Congratulations! But at the same time our losses gradually increased too. This was natural.” On this occasion the loss of eight Japanese aircraft was far from a disaster but the action reports of Japanese crews were far from ‘natural.’ Ultimately the gross misinformation provided by both Army and Navy aircrews prevented their commanders from taking realistic action to change tactics, attempt to upgrade equipment and training, or take other measures to improve results.

Japan’s senior commanders were not the only ones deluded in the performance of their aircrews. The Naval General Staff, after briefing Emperor Hirohito on the superb performance of Operations Y-1 and Y-2, sent Admiral Ugaki a message from His Majesty with the pleasing words then recorded in his diary, “… convey my satisfaction to the Commander in Chief, Combined Fleet, and tell him to enlarge the war result more than ever.”

By October 1943 it had become clear that the air battle over the Solomon Islands was taking its toll on the Japanese Navy Air Force (JNAF). An American intelligence report written in that month noted that Japanese pilots made glaring tactical mistakes, unnecessarily exposed themselves to gunfire, got separated and lost mutual support, and at times seemed to be completely bewildered. Both bomber and fighter pilots ceased to display the aggressiveness that marked their earlier combat. Bombers ceased to penetrate to their targets in the face of heavy fire, as they had formerly done; they jettisoned bombs, attacked outlying destroyers, gave up attempts on massed transports in the center of a formation. Fighters broke off their attacks on Allied heavy and medium bombers before getting within effective range, and often showed a marked distaste for close-in contest with Allied fighters.

Some Japanese officers were also becoming aware of deficiencies in the performance of the JNAF. Commander Ryosuke Nomura, who took over the role of air operations officer at Rabaul in 1943, became acutely aware of a decline in pilots performance. He attributed this to America’s better aircraft, an inability to sustain a high level of maintenance of their own equipment, and a decline in the experience and quality of available pilots. By the beginning of 1943 the number of experienced pilots, normally defined as having more than 600 hours flying, had fallen by 25 percent from its peak and in February the tipping point was reached, which saw pilots with between 300 to 600 hours outnumbering experienced pilots for the first time.

Within several months the JNAF would be sending pilots into battle with less than 200 hours flying time. These new pilots were not only disadvantaged in combat but also in the seeming basic task of preserving their equipment. In February 1943, operational losses of aircraft began to significantly exceed combat losses; 161 were lost on take-off, flight or landing mishaps while 104 were shot down by enemy action. The high command of the JNAF either seemed unaware of the need for rotational relief or simply did not have the resources to provide it. Combat flying is an exhausting and high stress activity and many experienced Japanese pilots must have perished because their levels of concentration collapsed. In the JNAF, pilots literally flew until they dropped.

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