decoy force to draw the main American fleet away from Leyte. The remnants of Japanese naval aviation were then limited to land-based operations, increasingly characterized by kamikaze attacks on American invasion fleets. From 16 December 1941 to 20 March 1945 IJN aviation casualties killed were 14,242 aircrew and 1,579 officers. Aircraft strength 1941 The IJNAS had over 3,089 aircraft in 1941 and 370 trainers. 1,830 first-line aircraft including: 660 fighters, including 350 Mitsubishi Zeros 330 carrier-based strike aircraft 240 land-based, twin-engined bombers 520 seaplanes (includes fighters and reconnaissance) and flying boats. Organization The elite of the pilots were the carrier-based air groups (Kōkūtai, later called koku sentai) whose size (from a handful to 80 or 90 aircraft) was dependent on both the mission and type of aircraft carrier that they were on. Fleet carriers had three types of aircraft: fighters, level/torpedo planes, and dive bombers. Smaller carriers tended to have only two types, fighters and level/torpedo planes. The carrier-based Kōkūtai numbered over 1,500 pilots and just as many aircraft at the beginning of the Pacific War. The IJN also maintained a shore-based system of naval air fleets called Koku Kantai and area air fleets called homen kantai containing mostly twin-engine bombers and seaplanes. The senior command was the Eleventh Naval Air Fleet, commanded by Vice Admiral Nishizō Tsukahara. Land based aircraft provided the bulk of Japan's naval aviation up to the eve of World War II. Each naval air fleet contained one or more naval air flotillas (commanded by Rear Admirals) each with two or more naval air groups. Each naval air group consisted of a base unit and 12 to 36 aircraft, plus four to 12 aircraft in reserve. Each naval air group consisted of several of nine, 12 or 16 aircraft; this was the main IJN Air Service combat unit and was equivalent to a in the Imperial Japanese Army Air Service. Each hikotai was commanded by a Lieutenant (j.g.), Warrant Officer, or experienced Chief Petty Officer, while most pilots were non-commissioned officers. There were usually four sections in each hikotai, each with three or four aircraft; by mid-1944 it was common for a shotai to have four aircraft. There were over 90 naval air groups at the start of the Pacific War, each assigned either a name or a number. The named naval air groups were usually linked to a particular navy air command or a navy