A kōkūtai () was a military aviation unit in the Imperial Japanese Navy Air Service (IJNAS), similar to the air groups in other air arms and services of the time. Some comparable units included group in the British Royal Air Force, gruppe in the German Luftwaffe, and groupe in the French Armée de l'Air. A kōkūtai could be based at land or on board aircraft carriers and could contain hundreds of men and aircraft. For example, the famous 343 Kōkūtai was a land-based fighter group while the 652nd Kōkūtai was a carrier-based bomber group. Kōkūtai were divided into smaller units called hikōtai, which were the equivalent of a squadron. Kōkūtai were usually divided into three hikōtai. In general, most pilots and aircrew in the Imperial Japanese Navy Air Service were non-commissioned officers. The word kōkūtai is abbreviated with the suffix "-ku" (空). The term "343 Ku", for example, stands for 343 Kōkūtai. In the Imperial Japanese Army Air Service (IJAAS) the equivalent unit was the sentai. Organisation Kōkūtai (air group) was equivalent to a US group or a RAF wing. A kōkūtai in the broadest terms could comprise a flight and base element of either a carrier or land based air group. In terms of the flight element, it was generally composed of 18 to 27 aircraft and took the name of the carrier or air station where it was originally formed. It could also be either homogeneous or composed of different types of aircraft. The land-based units had larger numbers of aircraft, and could number from approximately 24 to a 100 or more aircraft. They were more homogeneous and came under the command of the naval district where their home naval air station was located in, and later were designated either by a number or by the name of that particular station. The air groups and stations outside those ports were placed under the command of the nearest naval base (chinjufu). From the establishment of the IJN's first land based air unit at Yokosuka Air Group, Yokosuka until the end of the Pacific war, the term kōkūtai meant both a naval air station and the flying unit that was stationed there. The flying unit (hikōtai) operated the aircraft, and the rest of the personnel of any kōkūtai operated and maintained the ground facilities of the station at which the unit was stationed. Just as the aircraft and flight crew