This is an airspace of defined dimensions established around an aerodrome for the protection of aerodrome traffic.
The ATZ is intended to protect the aerodrome traffic, i.e. the traffic on the manoeuvring area and the traffic in the immediate vicinity of an aerodrome. This includes, but is not limited to, the aircraft in the aerodrome traffic circuit.
There are no worldwide-accepted definitions about the size of ATZs in terms of lateral or vertical limits. Generally, the ATZ is considered to be a “small-volume” airspace, usually a cylinder extending from the surface up to a few thousand feet with a radius of a few miles. The centre of the ATZ may be the aerodrome reference point (ARP), the centre of the (longest) runway, or another suitable point.
The airspace within the ATZ may be either controlled (and served by an aerodrome control tower) or uncontrolled (in which case e.g. aerodrome flight information service (AFIS) is offered).
References
- ICAO Annex 2