The use of a VHF radio isn’t mandatory for operations in most Class G airspace. However powered aircraft operating in Class G airspace above 5,000’ are required fly at the correct “cruising altitude” for their heading, and they are “recommended” to adhere to the correct “cruising altitude” when below 5,000’. Most aircraft operating in Class G airspace fly VFR so we as PG and HG pilots should hopefully be seen by any other aircraft even without making VHF calls.
But it's a different story in Class E airspace. There are many powered aircraft who choose to fly IFR in Class E airspace for a number of reasons. And when flying IFR, these aircraft don’t necessarily keep a good lookout for other traffic. So if you as a PG or HG pilot is flying at a “cruising altitude” and there is an aircraft operating IFR at that same altitude, then there’s a chance that you may not be seen. This is particularly true if you choose to disregard the legal minimum clearance from clouds (which I’m sure you all know).
The chance of any aircraft flying IFR through a cloud while in Class G airspace is “relatively” low, however the chance of an aircraft flying IFR in Class E airspace is relatively high. This means that the cloud you may be flying illegally close to in Class E may suddenly produce a very fast flying aircraft who not only isn’t looking, but is completely unaware of the potential of someone else being there.
I would consider it highly advisable to make occasional VHF calls on the appropriate area frequency stating your position and altitude, when operating in Class E, especially when operating above 8,500’. Class E airspace in our area begins above 8,500’ and this is particularly true above Killarney. All flights above 8500’ in the Killarney can only be conducted by appropriately equipped (carrying a VHF radio) and qualified (holding a VHF airband operators license) HGFA member. And I’d recommend that calls be made, especially if you are flying close to cloud.
By: Phil Hystek
Example: Brisbane Valley: CTAF Watts Bridge
Recommended reading HGFA - VHF Airband Radio Syllabus and Textbook PDF