Definitions — Page 11, Lesson 11

I want to walk you through the definitions that form the foundation of your communications knowledge. These are terms you must learn precisely, and I'll explain each one as we go. Let's start with aerodrome control service. This is the air traffic control service provided specifically to aerodrome traffic. So what is aerodrome traffic? It's all traffic on the manoeuvring area of an aerodrome — that means the runways, taxiways, and aprons where aircraft move under their own power — and all aircraft flying in the vicinity of an aerodrome. A note clarifies that an aircraft is considered in the vicinity of an aerodrome when it is on, entering, or leaving a traffic circuit. That brings us to the aerodrome traffic circuit. This is the specified path to be flown by aircraft operating in the vicinity of an aerodrome. It's the standard rectangular pattern you fly around the airfield — upwind, crosswind, downwind, base, and final. Next, the Aeronautical Fixed Telecommunication Network, which you'll hear called AFTN. This is a network of fixed, land-based stations used to send information such as NOTAMs — that's Notices to Airmen — weather, flight plans, departure and arrival information, and so on. Formerly this was mostly teleprinter information, but now it's increasingly a digital computer network, usually called AFTN. Now, the aeronautical mobile service. This is the service you will use whenever you use your radio. It includes all stations on the ground or in the air involved in the day-to-day operations of the aircraft. The formal definition is: a mobile service between aeronautical stations and aircraft stations, or between aircraft stations, in which survival craft stations may participate. Emergency position-indicating radio beacon stations — ELTs or EPIRBs — may also participate in this service on designated distress and emergency frequencies. An aeronautical station is a land station in the aeronautical mobile service. In certain instances, an aeronautical station may be located on board a ship or on a platform at sea. Air-ground communication is simply two-way communication between aircraft and stations or locations on the surface of the earth. Air-ground control clearance is the authorization for an aircraft to proceed under conditions specified by air traffic control service. When ATC says "cleared to..." that's the clearance. Air traffic service is a generic term that covers, variously: air traffic control unit, flight information service, alerting service, air traffic advisory service, air traffic control service, approach control service, or aerodrome control service. So it's the umbrella term for all these related services. Similarly, air traffic services unit is a generic term meaning, variously, air traffic control unit, flight information centre, or air traffic services reporting office. An airway is a control area, or portion thereof, established in the form of a corridor equipped with radio navigational aids. So it's like a highway in the sky, with defined boundaries and navigation aids to keep you on track. Altitude is the vertical distance of a level, a point, or an object considered as a point, measured from mean sea level. That's your height above sea level, not above the ground — that would be height, which is a different term. Finally, approach control service is the air traffic control service for arriving and departing controlled flights. This is the service that sequences you into the aerodrome and hands you off to the aerodrome control tower. These definitions are the building blocks. Learn them precisely, because every communication procedure you'll use is built on these exact meanings.