Even if that is true, Dick, when I am in a place where it is true:
- the 'high level airlines' will hear my beacon on 121.5
- anyone else within range at lower levels will hear my MAYDAY on Area, and
- those MEOSAR satellites will hear my beacon on 406 and relay the GPS position info.
We are really into risk mitigation / planning here rather than following some blind CASA mnemonic.
With the low GA traffic density that we have - the chances that someone GA will hear you on area frequency anywhere that you won't force land near a house is tattslotto territory.
With the poor coverage our ATC VHF system has at low levels (below 10,000ft), frankly I don't want to bet my life on a call on area frequency being heard.
If you go down in the metropolitan or farming areas of Australia, frankly this is all redundant because someone will see you.
The objective is not to declare an emergency or tell someone what happened. The objective is solely to have someone come to your aid on the ground. A farmer seeing you and calling 000 will do it.
In terms of a radio call, the highest probability that someone will hear you is an airline on 121.5.
ELT's are fine in theory, and psychologically comforting, but frankly the evidence overwhelming that they don't go off reliably in a crash. I might add that despite knowing this, we installed a 406 MHz ELT as part of our ADS-B upgrade.
If your aircraft still has an old 121.5 ELT, its batteries by now are very suspect. And beacon broadcasts on 121.5 are very difficult to locate. 121.5 has very marginal benefit for beacon transmission. If you don't have a 406 MHz ELT with GPS interlink, you're better off with an EPIRB.
Which brings us to a PLB or EPIRB. Where is yours? In the bottom of a flight bag? When will you trigger it? In flight, will you have time or be busy flying the aircraft and dealing with the emergency? On the ground, will you be conscious? Do your passengers know how to set it off? Have you briefed them? Do they know where to find it?
Frankly, I think the logic is inescapable that you should be monitoring 121.5 and that using it for an emergency call should be part of your emergency protocol