are they? I was unwrapping a couple for some airborne work this summer and the paperwork made it clear they weren't certified for airborne operation.
I wasn't sure whether this meant they could be used in the air or not? I asked a colleague and the consensus was that it is tolerated, mainly as it's for backup rather than routine.
Regarding the situation described above, I think that while it would be tempting to call ATC or advise the aircraft directly...due to potentially being taken for a pirate transmission or interference it's probably best to telephone emergency services or ATC and explain. While it might take a relatively long time, by the time you got through on RT and they actually took any notice etc I think it'd probably be quicker and more certain (and they would have gotten it from a source they wouldn't question).
CTG