WA Radio Scanner Users' Group

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Ground control channels are usually chosen by the Incident Controller based on local knowlegde and SOP. They are sometimes changed by ComCen or an ICV if signal quality or usage conflicts occur. The ground channel will almost always be one of the 8 simplex channels (46,47,48,49 or 96,97,98,99) to enable direct radio-to-radio communications. As the simplex channels do not use a repeater (unlike the duplex channels) they only transmit/receive within a few kilometres, depending on terrain and weather conditions. Therefore you will usually only hear ground control channels when fairly close to a fire ground.
Command channels, on the other hand, are normally duplex (repeater) channels chosen usually based on regional channel allocations, and can be heard over greater distance depending on your receive distance from the chosen repeater site.

This should really be in the FESA forum, and furthermore if you haven't already seen the thread the channels mentioned are listed here: http://vk6hgr.echidna.id.au/warsug/freq ... /FESA.html