Changes to AIRMET, SIGMETs and ARFORs from the 10th November 2016

The Bureau's Aviation Weather Services is changing the format of some aviation products, namely, low level area forecasts (ARFORs), AIRMETs and SIGMETs on the 10th November 2016.

Changes to AIRMETs and ARFORs

AIRMET advices are issued to provide pilots with information on the occurrence and/or expected occurrence of certain hazardous meteorological phenomena for low level flights that are not included within the valid ARFOR. AIRMET advices provide the relevant details of the hazard in a concise format and are complimentary to the routine issue and amendment of the ARFOR. AIRMET information is passed on to pilots by Air Traffic Control (ATC) by way of a Hazard Alert

The current format of the Australian AIRMET advice does not fully comply with ICAO Annex 3 requirements. Therefore, the Bureau will be introducing changes to its AIRMET format on the 10th November 2016 to align the AIRMET with the ICAO Annex 3 specifications. The new AIRMET will follow a very similar format to the existing SIGMET format.

From the 10th November 2016, the vertical extent of ARFORs and AIRMETs will be reduced to 10,000 feet above mean sea level (currently FL200). Weather information for airspace above 10,000 feet can be obtained from Medium and High Level Significant Weather (SIGWX) charts, Grid Point Wind and Temperature (GPWT) charts and the NAIPS Wind/Temperature Profile.

For more information, please refer to the following documents on AIRMET and ARFOR changes.

Changes to SIGMETs

In addition, the format of the Australian SIGMET will change slightly from 10 November.

Changes will be made to Australian SIGMET sequence numbers and the remarks line (RMK) as below:

Sequence numbers
The Australian SIGMET sequence numbers will no longer reset at 0001UTC, and instead the sequence numbering will continue until the SIGMET for the event is cancelled. Should more than 99 SIGMETs be issued for a particular event, the number portion of the sequence number will go from 99 to 02. Sequence number 01 will be reserved for new SIGMETs.

Remarks line
The status information (NEW, EXTD, CNL) will be removed from the remark line of Australian SIGMETs as this information can be determined from other sections as follows:

  • NEW – any SIGMET with a sequence number of one, such as X01, will always be a new SIGMET;
  • EXTD – any SIGMET with a sequence number greater than one, such as X02, will be an extension or a cancellation of a current SIGMET; and
  • CNL – Cancel information is contained in the body of the SIGMET.

For more information, please refer to the following documents on SIGMET changes.

Contact details

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