| 01 | Aerodynamics | Flight characteristics and problems of full-scale or model aircraft and their components as they are affected by the dynamics of air; Flight testing and wind tunnel testing. Includes theoretical and experimental aerodynamics as applied to missiles, See 16/02/01, Guided Missile Dynamics, Configurations and Control Surfaces. For the behavior of spacecraft in air, see 22/03, Spacecraft Trajectories and Reentry. For the aerodynamics of ground structures, see 13/13, Structural Engineering and Building Technology |
| 02 | Military Aircraft Operations | Military aircraft operations such as takeoff Operations and landing, air traffic, all weather and night flight, taxiing, approach, and inflight refueling; Flight safety; Ground safety; Aviation accident studies; Aircraft simulators and training devices. For missile operations, see Field 16, Guided Missile Technology. For spacecraft operations, See Field 22, Space Technology. For navigation and air traffic control, see 17/07/03, Air Navigation and Guidance. |
| 03 | Aircraft | Design, production, and maintenance of aircraft, aircraft components, and aircraft equipment; Structural studies of complete aircraft components such as airframes, bodies, and wings. Airworthiness; Crashworthiness; Aircraft damage assessment and vulnerability studies; effects of gunfire and blast on aircraft and flight equipment. For civilian aircraft, See 01/03/09, Civilian Aircraft. For specific types of aircraft, See subgroups 01/03/01 - 01/03/12. See also Field 16, Guided Missile Technology and Field 22, Space Technology. |
| 03/01 | Helicopters | Includes attack helicopters. For civilian helicopters, See 01/03/09, Civilian Aircraft. |
| 03/02 | Bombers | |
| 03/03 | Attack and Fighter Aircraft | |
| 03/04 | Patrol and Reconnaissance Aircraft | Includes observation aircraft. |
| 03/05 | Transport Aircraft | Includes tanker aircraft. |
| 03/06 | Training Aircraft | |
| 03/07 | V/STOL | |
| 03/08 | Gliders and Parachutes | Includes paragliders and kites, for both military and civilian applications. |
| 03/09 | Civilian Aircraft | Does not include aircraft modified for military use. |
| 03/10 | Pilotless Aircraft R.P.V.; Drones. | Includes full size aircraft when configured as drones. |
| 03/11 | Lighter-than-air Aircraft | Airships, blimps, dirigibles, balloons, for both civilian and military applications. |
| 03/12 | Research and Experimental Aircraft | Includes aerospace aircraft. |
| 04 | Flight Control and Instrumentation | Instruments, sensors, displays and recorders necessary for control and monitoring the flight of an aircraft; Cockpit and cabin display devices and onboard checkout systems; Onboard navigation display devices; Automatic pilots; Stability and control systems; Boundary layer control systems; Dynamic and static control devices. If the application of a flight control system is apparent, see the field where the application is treated. For devices used to compute flight times and headings, See 17/07/03, Air Navigation and Guidance. |
| 05 | Terminal Flight Facilities | Airports; Military air bases; Runways; Hangars; Ground refueling systems; Heliports; Aircraft handling and maintenance equipment; Taxiways; Parking aprons; Crash and fire facilities. For air traffic control systems, See 17/07/03, Air Navigation and Guidance. |
| 06 | Commercial and General Aviation | Civil aircraft operations, as described in 01/02. Also includes civil airport passenger and vehicle traffic studies. |