An aerodrome forecast (TAF) issued every 3 hours.

Satellite based augmentation system (SBAS)

No SBAS system should be used for navigation until the Australian SBAS system known as the Southern Positioning Augmentation Network (SPAN) is fully operational (expected 2024).

Closely spaced runways

Runways that are parallel or near parallel and spaced less than 1525m but not less than 1035m apart.


The combination of the two words, air and proximity. An occurrence in which aircraft come into such close proximity that a threat to the safety of the aircraft exists or may exist, in airspace where the aircraft are not subject to an air traffic separation standard, or where separation is a pilot responsibility.

Standard pressure

The pressure of 1013.2 HPa which, if set up on the pressure sub-scale of a sensitive altimeter, will cause the latter to read zero when at mean sea level in a standard atmosphere.

No-transgression zone (NTZ)

A corridor of airspace of defined dimensions located centrally between the two extended runway centre lines where controller intervention is required to manoeuvre aircraft when this airspace is penetrated by an aircraft conducting a simultaneous approach to a parallel instrument runway.


Notice to airmen: a notice distributed by means of telecommunication containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operations.