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Graphical area forecasts (GAF)

Graphical area forecasts (GAF) for operations surface to 10,000 ft AIP GEN 3.5

These domestic forecasts are issued for aircraft operations at or below 10,000 ft. They comprise of an image and supporting text detailing the meteorological conditions. GAFs are prepared and issued for the 10 areas as detailed on AUS PCA.

A flight forecast (text based forecasts) may be issued for any part of a flight for which a routine GAF is not prepared.

These forecasts are available from the ATS automated briefing systems, and briefing offices listed in ERSA GEN.

GAF areas

2___meteorology___area-forecasts___ARFOR_areas

Preparation and issue times

  • GAFs are issued with the 6 hour validity periods 2300Z to 0500Z, 0500Z to 1100Z, 1100Z to 1700Z and 1700Z to 2300Z
  • At each issue time two GAFs will be issued covering a 12 hour period, for example at 2200Z, both 2300Z to 0500Z and 0500Z to 1100Z GAFs will be issued
  • GAFs will be issued no later than 30min before the commencement of the validity period of the first GAF
  • the issuance of a new GAF replaces the previously issued GAF for the same validity period.

 

Approved abbreviations used in graphical area forecasts (GAF)

Abbreviation

Clouds

CU, TCU, SC, CB, ST, AS, AC, NS or combinations of these

Weather

CAVOK, MTW, NIL, TURB, and other abbreviations

Cloud amounts or descriptors

FEW, SCT, BKN, OVC and for CB, ISOL, OCNL, FRQ, EMBD, BASE, CLD ON GND

Qualifiers

MOD, SEV, +, –

Units

KT, KM, M, FT

Time

Z.
Variations

TEMPO and INTER are only used for critical locations. FM, TL, BECMG

Heights

ABV, BLW, LYR, SFC

Directions N, NE, E, SE, S, SW, W, NW
Corrections COR (correction), IMPR (improvement to conditions), TRANS ERR (transmission error), TYPO
(typographical error).
General FZLVL, FZLYR, WDSPR, WI, VAL, STNR, BTN and other abbreviations listed in AIP GEN 2.2 section 2.

Sections of the graphical area forecast (GAF)

The GAF shall comprise of:

  • a header giving details of issue time and validity times. It will also contain the word “CORRECTED” for a GAF correction
  • an image depicting weather areas labelled with an alpha character, e.g. A. Weather areas may be subdivided further with addition of a numerical character, e.g. A1. The weather in A1 will be the same as A with a minor differentiation, such as lower visibility in showers
  • a table providing detailed meteorological information for the areas shown on the image divided into four columns:
    • AREA gives the alpha character corresponding to areas in the image
    • SURFACE VIS and WX gives details of weather and associated visibility
    • CLOUD, ICING and TURB gives the cloud, icing and turbulence in the area or associated with the weather in the SURFACE VIS and WX column
    • FZLVL gives the height of the freezing level, or ABV 10,000ft where the freezing level is above 10,000ft AMSL
  • a legend explaining information important to the interpretation of the product
  • a remarks box for additional information including forecasts for critical locations and reason for correction for a corrected GAF.

Changes to GAFs and corrected GAF

GAFs are not amended. Advice of deteriorating conditions will be in the form of an AIRMET or SIGMET. A corrected GAF will be issued between standard issue times to notify of:

  • Typographical error (TYPO)
  • Errors such as transmitting before completion (TRANS ERR) and
  • Improvement in conditions (IMPR) – e.g. removal of fog, thunderstorms, etc.

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