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Aviation Meteorology

Acquiring aviation weather reports and forecasts

Rev. 10 — page content was last changed 26 January 2013
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13.1 The Bureau of Meteorology's Aviation Weather Service

The Australian Government's Bureau of Meteorology (BoM) is required to support civil and military aviation by the provision of aviation weather services in the form of weather observations, forecasts and warning or advisory material. The BoM also supplies selected aviation products to Airservices Australia for their online pilot briefing system — the NAIPS Internet Service [NIS].

The following aviation products can be accessed from the BoM Aviation Weather Services page — select the product category from those listed in the left-hand frame of the page.
Aviation forecasts
  • Low-level Area Forecasts [ARFOR] are a coded statement of the general weather situation for the lower levels of the atmosphere (up to 18 500 feet) and the expected conditions for a particular forecast area — the latter as detailed on the PCA or as indicated on the clickable map of Australia. The forecast period is not less than 9 hours or greater than 15 hours. The forecast is available at least one hour before commencement of the validity period. Pilots should regard forecasts as the best possible predictions from professional meteorologists supported with extensive computer modelling. However, meteorologists and computer modelling may not predict local micrometeorological events.

  • Terminal Aerodrome Forecasts [TAF] are a statement of the most likely meteorological conditions expected, for a specified period, in the airspace within the vicinity of the aerodrome. TAFs are issued for about one third of Australian aerodromes, at not less than six hourly intervals, and are usually valid for 12 hours. Most of the weather reports and forecasts are encoded using the World Meteorological Organization/International Civil Aviation Organization international weather code.

  • Area QNH

  • (Terminal) Trend Forecasts [TTF] are only issued for the 20 or so major airports and military bases. TTFs are an aerodrome actual weather report combined with a forecast of changes to conditions during the next three hours. The TTF was introduced to overcome the time-span deficiencies of the TAF.
Instructions on how to read the ARFORs, TAFs and METARS are available online at the BoM's 'Knowledge Centre', accessible from the right hand side of the Aviation Weather Services page. The older aviation eHelp section still exists on the BoM website. (If a user name is requested use 'bomw0007' and the password 'aviation'.) You may find other useful material via the 'Educational and reference' box.
Aviation observations
  • Aerodrome routine meteorological reports [METARs] are routine observations of weather conditions at an aerodrome issued on the hour or half hour, often through automatic weather stations. SPECI are special reports issued when conditions meet specified criteria.

  • Aerological diagrams and low level wind profiles are useful information for glider pilots.
Aviation weather packages
Click the 'Charts only' button from the options provided to display all of the following:
  • The latest Australian mean sea level pressure analysis
  • The latest Australian mean sea level pressure forecasts
  • The latest satellite image
The aerodrome weather information service [AWIS]
Automatic weather stations [AWS] are located at about 190 airfields. All the stations are accessible by telephone and about 70 are also accessible by VHF NAV/COMM radio. The access telephone numbers and the VHF frequencies of the AWS can be found by entering the 'Location information' page and downloading the pdf for the relevant state. For an example of the service from an AWS call 08 8091 5549 to hear the current automatic weather information broadcast at Wilcannia, NSW.
'Plain English' area forecasts, terminal aerodrome forecasts and meteorological observations
Ian Boag has produced an excellent, freely available, online, well-tested, plain language meteorological translator [PLMT] available on his 'pemet' site, providing current ARFOR, METAR and TAF within all Australian ARFOR areas decoded into 'plain English'. However, pilots must still get the NOTAM from the Airservices site.

Bear in mind that CAR 120 imposes penalties for use of forecasts that were not made with the authority of the Director of Meteorology, or by a person approved for the purpose by CASA, and it may be that plain English conversions are not authorised by the Director, but as the original section of code is presented under the decoded text, it is most likely that there is no problem with Ian Boag's excellent facility; it could be conceived as an learning tool for student pilots. Student pilots should be aware that the ability to decode BoM aviation reports and forecasts will be tested in some of the aviation examinations.
General weather observations, forecasts and radar images
Access to the latest general rather than aviation specific weather observations and forecasts plus satellite imagery (visible and infrared) are obtained via the BoM home page. Weather radar images (precipitation location and intensity), from about 50 weather watch radars, are updated at 10 minute intervals. The images from individual radars cover an area of 256 km radius but may be combined into a larger mosaic. The last four snapshots from each radar can be looped to provide a good indication of current storm development, intensity plus the direction and rate of movement. Lightning tracker websites such as Weatherzone provide useful information on current storm location and movement.

13.2 Airservices Australia's NAIPS Internet Service

The most convenient way to download the coded ARFOR, TAF and METAR plus the NOTAM is from Airservices Australia's NAIPS Internet Service [NIS], 'a multi-function, computerised, aeronautical information system. It processes and stores meteorological and NOTAM information as well as enabling the provision of briefing products and services to pilots and the Australian Air Traffic Control platform'.

NIS is accessed through the internet with any web browser or access may be integrated within flight planning software. The Bureau of Meteorology provides all the weather products to the NIS.

You must register with AsA before you can access the NIS. You are required to create a 'user name' and a password. If you don't have an ARN or Pilot Licence Number leave that field blank, don't use your RA-Aus or other sport and recreational organisation membership/Pilot Certificate number, it may conflict with someone's Aviation Reference Number. Download the NIS user manual (1.6 MB).

When registered, you can log in; enter user name and password, and then click the required link. If you choose 'Area Briefing' you can select up to five briefing areas by clicking on the map or by entering the required areas in the entry boxes, and then click on the 'Submit Request' button. The ARFOR plus TAFs and METARs and NOTAM for the aerodromes in that area will be presented in the form of a pre-flight briefing. See an actual briefing with explanatory notes added. For further information read the weather check section of the Flight Planning and Navigation Guide.

13.3 Acquiring weather information in flight

There are several means of obtaining a limited amount of weather information while airborne:
  • AERIS — the Automatic Enroute Information Service network
  • ATIS — the Automatic Terminal Information Service at some aerodromes
  • AWIS — the Aerodrome Weather Information Service at all automatic weather stations can be accessed by telephone and about 70 of them also provide VHF access.
  • FLIGHTWATCH — the on-request service provided by Airservices Australia.
For further information read the acquiring weather information section of the VHF Radiocommunications Guide.
Inflight weather warning broadcasts by Air Traffic Services
  • SIGMETs report the occurrence or expectation of significant meteorological events such as widespread duststorms, a severe line squall or heavy hail. SIGMETs are issued by the BoM but broadcast by the Air Traffic Service for the affected area as a hazard alert; see AIP GEN section 5.1.

  • AIRMETs report the occurrence or expectation of less severe meteorological events and applies only to aircraft operating below 10 000 feet. AIRMETs are issued by the BoM but broadcast by the Air Traffic Service as a hazard alert for the affected area; see AIP GEN section 5.3.

13.4 AIP Book and ERSA

Airservices Australia publishes online versions of the AIP Book and ERSA at www.airservicesaustralia.com/publications/aip.asp. You must click the 'I agree' button to gain entry. For further information about the meteorological service reports and forecasts, read the section AIP GEN 3.5 (about 50 pages). To find a particular section of AIP or ERSA you have to click through a number of index pages. The section/sub-section/paragraph numbering system is designed for an amendable loose leaf print document and you may find it a little confusing as an on-line document.

This concludes the Aviation Meteorology Guide — which I hope you have found useful — and an email is always appreciated.

I have written six other tutorials which should be useful and informative. These cover:
    •   Flight theory
    •   VHF radiocommunications
    •   Flight planning and navigation
    •   Coping with emergencies
    •   Decreasing your exposure to risk
    •   and a Builders guide to safe aircraft materials.

... John Brandon

Copyright © 2000–2013 John Brandon     [contact information]