Australian Flying — November-December 2017

58 Graphical Weather Forecasts

AUSTRALIAN FLYING November – December 2017

Briefings and

Area QNH

Many pilots use the area briefing

function of NAIPS to access a pre-

defined set of briefing products.

A NAIPS Area Briefing will

currently return the forecast

Area QNH, ARFOR, TAF

for locations within that area,

SIGMET, AIRMET, AIREP

and NOTAM. The Specific

Pre-Flight Information Bulletin

(SPFIB), used extensively for

route f lying, provides similar (but

not the same) information.

These familiar Area Briefings

will continue to be available,

must obtain AIRMETs to

ensure they have the current area

forecast information. Although

AIRMETs have been available for

some time, some pilots don’t seem

to be using them.

Distributing the GAF

Thanks to EFB technology the

way pilots obtain and use weather

forecasts and other briefing

materials has changed markedly in

the last five years.

Many GA pilots now use

CASA-approved EFB tablet

apps, which assimilate a pilot’s

f light plan with NAIPS briefing

information, enroute and approach

charts, navigation, live weather and

traffic data. More than a few of

us are now f lying with no printed

briefing materials, and a GAF that

could only be printed on paper

would be of limited practical use.

The Working Group made contact

with the major EFB and f light

planning software developers,

from which technical requirements

were defined to ensure the new

forecast could be used with those

systems.

Nevertheless, it is also essential

that f light briefing materials are

accessible without an EFB. An

additional complication is that

forecasts for operational use must

be distributed by Airservices

Australia, and not the Bureau of

Meteorology.

with GAF and GPWT replacing

the corresponding ARFORs.

Forecast Area QNH, which

historically has been mapped to

the ARFOR boundaries, will also

still be included.

For clarity, these areas are being

renamed Briefing/QNH Areas,

and will be shown along with the

new GAF boundaries, on PCA

and ERSA charts.

GAF Validity and

Amendment

GAFs will be issued every six

hours, but two at a time, with

each valid for six hours. They will

typically be available from about

one hour, but no less than 30

minutes, before becoming effective.

This means that even briefings

obtained right before the cutover

time will still contain a forecast

valid for more than six hours.

Because the GAF is in graphical

form, it’s not possible to reliably

amend it in words. So, when a

forecaster expects conditions

to change, to worse than those

forecast in the GAF, an AIRMET

will be issued. An AIRMET is a

statement of the expected change

to the forecast conditions, and

unlike a GAF, can be readily

communicated in words, including

over the radio if required.

When AIRMETs are issued

ATC will broadcast their

availability on relevant area

frequencies and a pilot can request

the details as necessary.

When conditions are expected

to be better than forecast there

is no immediate safety issue and

a corrected GAF will be issued

instead.

It’s vital, as part of this

changeover, that pilots understand

that GAFs will not be amended

like ARFORs, and that they

LEFT: ARFORs to be replaced

by GAF and GPWT from 9

November 2017.

RIGHT: Features of the new

GAF and GPWT, compared

with previous ARFOR.

BELOW LEFT: EFB Products

will be able to display GAFs,

integrated with other flight-

critical information

Example of an AIRMET.

BUREAU OF METEOROLOGY

INDICATIVE SAMPLE, COURTESY AVPLAN EFB