8/15/19 1/30/20  Pilot/Controller Glossary Pilot/Controller Glossary  AIR CARRIER DISTRICT OFFICE- An FAA field  office serving an assigned geographical area, staffed  with Flight Standards personnel serving the aviation  industry and the general public on matters related to  the certification and operation of scheduled air  carriers and other large aircraft operations.  AIR DEFENSE EMERGENCY- A military emer- gency condition declared by a designated authority.  This condition exists when an attack upon the  continental U.S., Alaska, Canada, or U.S. installa- tions in Greenland by hostile aircraft or missiles is  considered probable, is imminent, or is taking place.  (Refer to AIM.)  AIR DEFENSE IDENTIFICATION ZONE (ADIZ)- An area of airspace over land or water in which the  ready identification, location, and control of all  aircraft (except for Department of Defense and law  enforcement aircraft) is required in the interest of  national security.  Note: ADIZ locations and operating and flight plan  requirements for civil aircraft operations are  specified in 14 CFR Part 99.  (Refer to AIM.)  AIR NAVIGATION FACILITY- Any facility used  in, available for use in, or designed for use in, aid of  air navigation, including landing areas, lights, any  apparatus or equipment for disseminating weather  information, for signaling, for radio-directional  finding, or for radio or other electrical communica- tion, and any other structure or mechanism having a  similar purpose for guiding or controlling flight in the  air or the landing and takeoff of aircraft.  (See NAVIGATIONAL AID.)  AIR ROUTE SURVEILLANCE RADAR- Air route  traffic control center (ARTCC) radar used primarily  to detect and display an aircraft's position while en  route between terminal areas. The ARSR enables  controllers to provide radar air traffic control service  when aircraft are within the ARSR coverage. In some  instances, ARSR may enable an ARTCC to provide  terminal radar services similar to but usually more  limited than those provided by a radar approach  control.  AIR ROUTE TRAFFIC CONTROL CENTER  (ARTCC)- A facility established to provide air traffic  control service to aircraft operating on IFR flight  plans within controlled airspace and principally  during the en route phase of flight. When equipment  capabilities and controller workload permit, certain  advisory/assistance services may be provided to VFR  aircraft.  (See EN ROUTE AIR TRAFFIC CONTROL  SERVICES.)  (Refer to AIM.)  AIR TAXI- Used to describe a helicopter/VTOL  aircraft movement conducted above the surface but  normally not above 100 feet AGL. The aircraft may  proceed either via hover taxi or flight at speeds more  than 20 knots. The pilot is solely responsible for  selecting a safe airspeed/altitude for the operation  being conducted.  (See HOVER TAXI.)  (Refer to AIM.)  AIR TRAFFIC- Aircraft operating in the air or on an  airport surface, exclusive of loading ramps and  parking areas.  (See ICAO term AIR TRAFFIC.)  AIR TRAFFIC [ICAO]- All aircraft in flight or  operating on the maneuvering area of an aerodrome.  AIR TRAFFIC CLEARANCE- An authorization by  air traffic control for the purpose of preventing  collision between known aircraft, for an aircraft to  proceed under specified traffic conditions within  controlled airspace. The pilot-in-command of an  aircraft may not deviate from the provisions of a  visual flight rules (VFR) or instrument flight rules  (IFR) air traffic clearance except in an emergency or  unless an amended clearance has been obtained.  Additionally, the pilot may request a different  clearance from that which has been issued by air  traffic control (ATC) if information available to the  pilot makes another course of action more practicable  or if aircraft equipment limitations or company  procedures forbid compliance with the clearance  issued. Pilots may also request clarification or  amendment, as appropriate, any time a clearance is  not fully understood, or considered unacceptable  because of safety of flight. Controllers should, in  such instances and to the extent of operational  practicality and safety, honor the pilot's request.  PCG A-4  AIM- (See AERONAUTICAL INFORMATION  MANUAL.)  AIP [ICAO]- (See ICAO term AERONAUTICAL  INFORMATION PUBLICATION.) 