Helicopters get bombarded with Mexico traffic in So Calif. If all ground units at least Tx the PL, the helos can actually monitor the channel instead of turn it down. BK radios (if programmed with CSQ on the Rx side) will actually DISABLE the Tx PL tone if switched to talk-around mode which is why my agency went with Rx and Tx.
The aircraft receive issue (interference from Mexico) I knew about but the BK radio behavior I was unaware of.
In any case, I think it's obvious that putting receive CTCSS protection on most if not all such frequencies is ideally desirable and necessary and likely ultimately inevitable. The problem is, well, the real world is not "ideal" - how do we ensure full and perfect compliance across the board especially during the period of transition? It's easy to say it's simply a matter of adding only one more element to the channel programming per radio but I can see the point of view of the folks in charge of such efforts and their fear of getting blamed for the "system failing" when just one or a few radios in the field don't get their tones set right and they happen to be involved in a major incident even if those effected units were not their responsibility in the first place.
Frequent training between and among disparate groups of users with radios programmed by their respective radio services can weed out some of it, I suppose. But, no matter how hard you try to prevent them, problems will creep in and failures occur. Special use mutual aid inter-agency channels are probably the most prone to this kind of problem in the sense that they are less frequently used during normal operation so problems in programming might not show up until extreme circumstances are already in play.
-Mike
