Backup audio feeds are excellent if one can afford them. Unfortunately, sometimes one can't.
Moreover, backups have to be regularly tested to make sure they'll work when they're needed.
This is an excellent point. Although we're getting a little into thread drift, it's worth mentioning that over the last 20-odd years there has been a subtle but definite shift in the concept of "reliability" when it comes to telecommunications as a whole. It used to be that reliability was paramount above all. For example, remember in the 1980's when if your phone...which was almost invariably a landline with no wireless component at all...went out it was a big deal? And it almost always signified that a tree had fallen and taken a telephone pole with it, or some similar issue. I distinctly remember being a kid during Hurricane
Gloria in 1985 and marveling that although our neighborhood lacked AC power for nearly a week, the phone worked just fine the entire time.
Cellphones, among other things, changed all that. Now convenience trumps reliability, and we think nothing of having a phone that often will not work well, or at all. I'm not saying this is bad or good, per se. I am saying that mindset extends to ALL telco so it's damn hard to have a truly foolproof backup system. A "redundant" T1 or ISDN...or even a "landline" phone...is all too frequently carried on the same circuits as the mainline...and thus just as susceptible to problems as the mainline is. Anything wireless...licensed or unlicensed...might work fine in normal times, but in an emergency it can croak as the overall situation changes. (think
Katrina when, at first, the cell networks were technically functioning but were totally overwhelmed) Even satellite, an expensive "backup", can die on you if your dish is blown away in a storm.
Used to be that the old DACBUC calculation (Dead Air Cost vs Back Up Cost) was pretty straightforward. If being off-air cost you X dollars in advertising make-goods and lost audience, then you paid Y dollars to have a backup. And usually if you did things right and spent the money appropriately, you could get a truly redundant backup that you could feel solid about. Otherwise your DACBUC calculation would show that it wasn't worth enough money to do it right, and made do without. A lot of college stations are like that, for example...it costs them little to be off the air, even for days, so they don't spend much on backups.
Nowadays, even if you spend a lot of money that's justified under DACBUC, it's still something of a crapshoot that your backup will be there when you need it. And, conversely, you can spend comparatively little money and get at least
some functionality in a backup. This makes things harder, especially when the boss is looking at a backup solution that costs $500 and thinking it'll work just as well as a solution that costs $50,000. And the hell of it is, he might be right...but not because the $500 is that good, but rather because the $50,000 solution is that unreliable!