Wind shear warning service
General AIP GEN 3.5
Aircraft reports of wind shear encountered during climb and descent are the primary means of detecting wind shear. When possible, the MET forecasting office provides advice on the likely duration of the event and forecast low-level winds.
When wind shear has been reported or the meteorological situation has been assessed as a risk, then a wind shear warning is issued.
Wind Shear Warnings for an event will specify a validity period and sequence numbers will be assigned to each warning associated with an event. A wind shear warning will be cancelled when wind shear is no longer expected.
This service is provided at Cairns, Brisbane, Sydney, Melbourne, Adelaide, Darwin, Perth, Hobart and some defence locations.
When windshear is forecast, or reported by pilots at an intensity greater than ‘light’, this information, together with a forecast low-level wind, will be included on the ATIS at any of the above aerodromes.
Aerodrome weather reports are observations of meteorological conditions at an aerodrome. The reports are generated by electronic recording devices called automated weather stations (AWS) and may also have manual input by approved observers.
Routine reports (METAR) are issued at fixed times, hourly or half-hourly, and are made available at pre-flight briefing or on request to aircraft in flight.
Special reports (SPECI) are aerodrome weather reports issued whenever weather conditions fluctuate about, or are below, specified criteria.
Take-off and landing reports are provided at aerodromes with a control tower.
This service may also be provided by a CA/GRS or UNICOM, details of which can be obtained in ERSA.
Take-off and landing reports are included on ATIS, where available, or passed to aircraft reporting taxiing or inbound. Take-off and landing reports contain, as available, the following:
- wind velocity, with direction in degrees magnetic
- altimeter setting
- air temperature (if appropriate to the type of aircraft)
- low cloud, if significant
- visibility, if significant – in metres up to and including 5000 m; above this value, in km (a visibility greater than 10 km is given as ‘visibility greater than 10 km’)
- additional items, that is extent of cloud below the main ceiling, disposition and intensity of rain, reported turbulence area, presence of freezing fog etc and
- CAVOK – when the following conditions are observed to occur simultaneously:
- visibility of 10 km or more
- nil significant cloud that is no cloud below 5000 ft, or below the highest 25 nm minimum sector altitude, whichever is the greater, and no CB or TBU at any height; and
- nil significant weather, that is none of the weather phenomena listed on page 2.36.
When the term CAVOK is used, low cloud, visibility and additional items will not be advised.
The meteorological information provided by air traffic controllers may be obtained by observation of the whole horizon, or only of the probable flight path of an aircraft. Reports based on AWS data will be limited to wind direction and velocity, QNH and temperature, except when a qualified observer at the aerodrome provides visually observed information.
Approved observers are officers of the BoM, air traffic controllers, and other persons on the ground approved for the purpose by the BoM and/or CASA.
For the purpose of observing visibility for take-off and landing at an aerodrome, the pilot in command shall be deemed an approved observer for that flight.
The location of the observing point for the aerodrome weather reports is such that the meteorological conditions observed within visual range, or interpreted from instruments at that point, are representative of conditions at the aerodrome.
Aircraft weather reports
The pilot in command of an aircraft is required to observe and report en-route meteorological conditions as prescribed in AIP GEN 3.5 (regarding AIREP) (see page 2.63). For this purpose, they are deemed an approved observer.
In addition to requirements for special AIREP reports concerning MET conditions likely to affect the safety of other aircraft, pilots in areas where ground meteorological reports are scanty are encouraged to report observations of MET conditions which they consider will assist in the provision of meteorological services.