World Wide Aviation VOLMET HF

Last Update: May 26, 2004. Subject: Aviation HF Worldwide

Aviation Automatic VOLMET Weather Information HF Broadcast System

The VOLMET (A French word which means “flying weather”) system broadcasts Meteorological Bulletins at prescribed times for specified durations, repeating individual reports as required to fill the broadcast time slot These reports can be tuned into by pilots all over the world that are equipped with HF frequencies. In a way, they are a HF (high frequency for long distances) version of the ATIS (Automatic Terminal Information Service) provided at most airports on the VHF air band.. See the Table of Frequencies, Times & Locations below and you too can listen in with your scanner, HF Comms Receiver or Short Wave radio with SSB capabilities. VOLMET Broadcasts can be heard on Aviation HF frequencies, using USB mode (as are all aviation HF communications).

Note: 3.1765MHz= 3176KHz 1278KHz=1.278MHz etc etc

*Broadcast Station*	*Frequencies (MHz) USB*	*Time Of Broadcast*
Antofogasta VOLMET	3.1765, 7.4655	Continuous
Auckland VOLMET	2.8630 6.6790, 8.8280, 13.2820	20 & 50 minutes
Bangkok VOLMET	2.9650, 6.6760, 11.3870	10 & 40 minutes
Beirut VOLMET	3.0010, 5.5610, 8.8190	15 & 45 minutes
Bombay VOLMET	2.9650, 6.6760, 11.3870	25 & 55 minutes
Australia VOLMET	2.9650, 6.6760, 11.3870	00 & 30 minutes
Calcutta VOLMET	2.9650, 6.6760, 11.3870	05 & 35 minutes
Edmonton VOLMET	6.7530, 15.0350 (Military)	20 & 22 minutes
Gander VOLMET	3.4850 6.6040, 10.0510, 13.2700	20 & 30 minutes 50 & 60 minutes
Hong Kong VOLMET	2.8630, 6.6790, 8.8280, 13.2820	15 & 45 minutes
Honolulu VOLMET	2.8630, 6.6790, 8.8280, 13.2820	00, 10, 30 & 40 minutes
Johannesburg VOLMET	3.0470, 6.7160, 9.0260,	0400hrs to 2100hrs UTC
Karachi VOLMET	2.9650, 6.6760, 11.3870,	15 & 45 minutes
Lahr VOLMET	5.6900, 13.3210	Continuous
New York City VOLMET	3.8850, 6.6040, 10.0510, 13.2700	10, 15, 40 & 45 minutes
Puerto Montt VOLMET	5.2800	Continuous
Rio De Janeiro VOLMET	2.8810, 10.0870	Continuous
Shannon VOLMET	3.4130, 5.5050, 8.9570, 13.2640	00, 25, 30 & 55 minutes
Singapore VOLMET	6.6760, 11.3870	20 & 50 minutes
St Johns VOLMET	6.7530, 15.0350	40 & 50 minutes
Trenton VOLMET	6.7530, 15.0650 (Military)	30 & 35 minutes
West Drayton VOLMET	4.7220, 11.2000 (RAF)	Continuous

Key To Table: 15 & 45 minutes means that at every hour at 15 and 45 minutes past the hour (1015, 1345, 1715, 0345) these stations transmit their scheduled program. From Australia, Auckland, Brisbane, Singapore are most commonly heard VOLMETS. The others can be received with good antennas and right atmospheric conditions, “skip”.

The VOLMET Operating System (How they make what we’re listening to):

Although designed to run completely unattended, a simple graphical interface is provided for an operator to set up and modify VOLMET Bulletin content and Schedule. This takes the form of an Area map of the FIR (Flight Information Region) or FIRs that contain the locations for which Meteorological reports are expected. To define the report content of a VOLMET, the operator depresses the buttons for each report to be included, in the order required, and ‘Assigns’ this selected set to a Bulletin. Up to 50 different Bulletins can be pre-defined in this way.

Any defined bulletin can be ‘Assigned’ to a schedule entry specifying the start time and playing duration. A schedule entry can be made to repeat each hour or play only once each day. The Scheduler can accept multiple entries.

In normal operational mode, new reports are received from the AFTN or OPMET database in either WMO code or plain text. As each report is received it is decoded and an audio voice file prepared using a library of pre-recorded words and phrases. This audio file is linked to a specific button on the Map corresponding to the reports geographic location. The button colour is set to Yellow when a current report exists. An operator may audibly check any report (or set of reports) or by clicking the buttons and the clicking play on the Audio Control Panel. When the scheduled time arrives, all the reports that comprise the scheduled bulletin are broadcast, repeating if necessary to fill the specified duration using the most recent report for each location.

Two operator override options can be enabled.

1) Operator keyboard entry, using a text window, of report data which is subsequently translated to an audio file using the Text To Speech module.

2) Operator direct recording of a report using a microphone.

Up to 8 VOLMET systems can be networked giving a single operator control over all 8 systems.

A transmitter control relay simulates ‘push to talk’ for the duration of the broadcast.

Audio output is via a 600-ohm line isolating transformer providing a balanced signal adjustable for -10dbm to +5dbm suitable for direct connection to a two wire telephone circuit.

Natural Voice Broadcast Option.

This option provides the repetitive broadcast of bulletins of unspecified report types, such as flight arrivals and departures, where the individual items are recorded direct via a microphone. In all other respects it is the same as the VOLMET system.

Download this file as an: Excel XLS, Works DB or AOR MEM File from the files section of the Australian Scanning Group

Brought to you by Ashley Geelan & Mike Smith.

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The information contained on this page is International Public Domain Information available to any Australian via the ICAO web site or the Air Services Australia Web site.