more permanent, were established in December 1938. Two of these were established before the Pacific War: the 11th was organized in December 1938, and the 12th was formed in 1939. Until the very end of the 1930s most kōkutai were composed of a mix of aircraft types, with seaplanes predominating initially, but with carrier-type fighters, dive bombers, and torpedo bombers increasing in numbers, along with land-based twin engined medium bombers. However, by 1941 the IJN's land-based air groups were almost always composed of one type of aircraft, the exception was the Chitose air group which was based in Micronesia and was composed of both medium bombers and fighters. On November 1, 1942, all land-based identified with base names were given numerical designations. As the war in the Pacific progressed, this structure lacked flexibility and hampered front-line operations, consequently, in March 1944 the IJN's land-based air forces were restructured, and certain hikōtai were given independent numerical designations and an identity of their own outside the parent Kōkūtai. Hikōtai Hikōtai was a flight echelon of a carrier or a land-based kōkūtai. It was commanded by a Hikōtaichō and consisted of all flight personnel of kōkūtai (the rest of kōkūtai was composed of ground echelons that provided aircraft maintenance and air base service functions). Hikōtai was divided into several smaller divisions, called buntai. Buntai Buntai was the smallest administrative unit of aviation personnel, as opposed to tactical or operational formations of aircraft. It was commanded by a Buntaichō and was made up of the required number of personnel necessary to fly and maintain one chutai, which typically consisted nine aircraft. The number of personnel in a buntai would vary, depending on the mission or role of the unit and type of aircraft that it operated. Although the terms buntai and chutai were used interchangeably by naval aviators, buntai referred to the personnel while chuntai referred to the aircraft or tactical formation in the air. Tactical and Operational Formations Hikōkitai Hikōkitai, (flying units) were a flight echelon of a carrier that took the name of the carrier on which it was on, i.e. Hikōkitai. Daitai, Chūtai, Shōtai A Daitai consisted of 18 aircraft. A Chūtai consisted of 9 aircraft while a Shōtai has 3 aircraft Naval Air Group identification And before 31 October 1942 Place name; Standing air group (常設航空隊, Jōsetsu-Kōkūtai). Numbered name; Special setting air group (特設航空隊, Tokusetsu-Kōkūtai). And after 1 November 1942