There are a few things to untangle in this question. First, there is a difference between carrier-qualified personnel and naval aviators. Now the IJN like other navies could and did transfer carrier-based units for land-based operations. The IJN famously did this in November 1943 where it temporally transferred 170 carrier aircraft to Rabaul for operations against the Americans. The Fifth Air Force immediately noted that the quality of Japanese pilots improved over what had been the norm. This was a reflection that carrier-qualified personnel tended to have higher training than land-based pilots, even if they flew the same type of aircraft. Carrier-qualifications was an extra level of training for most naval aviators and the carrier training programs tended to choose among the more promising pilots. So when talking about the adjustments to Japanese training and replacement strategies, carrier crews was a part of this larger trend, but also had special needs that were different than their land-based counterparts.

Secondly, the losses of trained pilots and aircrew at Midway were really not that severe. The notion that an entire air strike was waiting to take off before the SBDs destroyed the three carriers has been proved as a postwar fabrication by historians like Jonathan Parshall and Antony Tully. The claim of catastrophic losses in pilots at Midway was absent in many of the immediate postwar debriefings of key IJN personnel and only first appeared with Mitsu Fuchida's account of the battle. Using Japanese records, Tully and Parshall estimated that of the 480 total aircrew of Kido Butai, only 110 perished in the battle with the bulk of them coming from Hiryu, whose pilots fought out the remainder of the battle after the fatal dive bomber attacks. Midway inflicted severe losses in trained maintenance personnel and aircraft, but it did not break the back of the Japanese carrier aviators. There were reserve squadrons available and many of the surviving Kido Butai pilots and aircrew transferred to either shore units or the surviving and new carriers and it was these pilots that were fed into the carrier battles around Guadalcanal. It was the high level of attrition in battles like Santa Cruz that denuded the IJN of its post-Midway veteran carrier aircrew. Both Midway and the Coral Sea battles contributed to this larger trend of whittling down experienced carrier aviators, but they did not create it. Contrary to the popular image of Axis pilots never being rotated home, most of the surviving carrier veterans were rotated back to the Home Islands at the end of 1942 for rest and training, but were forced back into the fray in the latter part of 1943.

On the whole, this collective picture was indicative of a training and replacement establishment that was ill-suited for the needs of a protracted war. The IJN's went to war in 1941 with a training regimen and structure that was designed to meet prewar needs. The washout rate for prewar IJN pilots hovered around 40% and memoirs of many pilots and aircrew describe a curriculum that at times was more about hazing out soft recruits than determining actual skill in the air. Most prewar pilots averaged about 500 hours flight time training with carrier-qualified personnel having even more hours. This was not a curriculum that could produce replacements quickly or efficiently. The prewar classes for aircrew lasted from anywhere between eight months to over a year with carrier crews sometimes having a total of two to three years training.

To be fair to the IJN, a number of officers within the service did recognize that the training regime needed to be revamped and streamlined. There was a merging of instructional classes over the course of 1940/41 that shaved some two months off of training and the IJN began to drop a number of its prerequisites to enter into flight training. The advent of the Pacific War also witnessed the IJN funneling in personnel into combat units before they had completed their training. While the carrier forces still remained highly-trained, a number of the land-based units at the time Pearl Harbor, especially the Eleventh Air Fleet, had a number of undertrained aviators among their ranks.

This policy of shortening training and cutting corners wholesale only accelerated with wartime pressures. The IJN telescoped a number of its training classes to feed more pilots into the frontlines. Additionally, shortages of fuel, engines, and aircraft meant the IJN prioritized the production and fueling of frontline combat aircraft over trainers. New IJN pilots in the 1943/44 were lucky to log over a hundred hours of flight time, which was a far cry from the averages of five hundred flight hours of the Pearl Harbor aviators. The losses of carrier pilots in 1942 had forced the IJN to revamp the structure of its carrier airwings, but the replacements trained over the course of 1943 were a far cry from the capabilities of earlier cohorts. The lack of training showed during the Battle of the Philippine Sea in which IJN carrier pilots had difficulty making coordinated attacks over long-range. On paper, the IJN possessed a balanced force that was numerically stronger than before; Ozawa's nine carriers fielded slightly more aircraft than Nagumo's in 1941 and the IJN also had considerable shore-based airpower. The IJN training classes also peaked in August 1944 with some 4000 trainees. But these numbers were deceptive in that Japanese airpower was fracturing. The pilots and aircrew only possessed a modicum of skills needed to do their duties and they were coming up against an enemy that was both qualitatively and quantitatively superior. The aptly-named Marianas Turkey Shoot was a natural end-result of these policies.

Japanese carrier-based airpower died in the Marianas although it took a few months for the IJN to realize this. There were attempts to enfold the surviving carrier pilots into new carrier air groups along with trainees in September 1944 with the hopes of having enough in training to be carrier-capable by January 1945 using both surviving carriers and new construction like the carrier Shinano for a new mobile fleet. But events superseded these plans. The premature triggering of the air component of the Sho plan over Taiwan led to yet more IJN air losses, including those shore-based pilots earmarked for eventual use in the carriers. The IJN then elected to use its surviving operational carriers and their skeleton air groups as bait for the Leyte operation. The result of the losses of carriers at Cape Engaño was that the IJN lost most of its operational flattops and its new construction such as Unryu were only barely operational at best. The IJN quietly abandoned carrier-based airpower in the first quarter of 1945 as losses of carriers mounted and fuel shortages not only prevented personnel from becoming carrier-qualified, but also kept the few surviving or barely-completed carriers in port.

All of this does lead to the question of whether or not the Japanese could have done anything differently. There really was not much in hindsight that the Japanese could have done to alter the course of the war. The 1942 attrition battles around the Solomons were destructive and had the Japanese elected not to fight them, that would have ceded the initiative to the Americans. The IJN carrier fleet might have been in a stronger position in 1943 to challenge the Americans in the Gilberts, but the qualitative gap had already opened up between the two forces. The American Essex-classes were entering service while the IJN fielded no new fleet carriers in 1943. The training program was already cutting corners even as the war started and persistent shortages of material placed a ceiling on the numbers of qualified aircrew the Japanese could field. In such a scenario, a more husbanded IJN carrier fleet might have performed better in 1943 than they did in 1944, but the odds were still very much stacked against the Japanese.

Sources

Peattie, Mark R. Sunburst: The Rise of Japanese Naval Air Power, 1909-1941. Annapolis, Md: Naval Institute Press, 2001.

Parshall, Jonathan, Anthony Tully, and John B. Lundstrom. Shattered Sword The Untold Story of the Battle of Midway. Herndon: Potomac Books, 2011

Prados, John. Storm Over Leyte: The Philippine Invasion and the Destruction of the Japanese Navy. New York: New American Library, 2016.

Tagaya, Osamu. Imperial Japanese Naval Aviator 1937-45. London: Osprey Pub, 2014.