Bearfoil, "JD-EE, For purposes of this discussion, and a proposed fit of enhanced Comm over areas of low likelihood of FDR/CVR recovery, wouldn't ice be considered a similar deck as land?"
Ice is going to be very pure water, which is an insulator. It will have a different dielectric constant. So there will be some reflection. It also is not a very good insulator so there will be dissipation. I do know that you can speak by radio, sometimes. from Antarctica to the US on amateur radio. But that's using techniques for low angle radiation rather than NVIS, which has a design range of a couple hundred miles. In practice it works fairly well from ONT up towards Portland, Or. and Seattle at night. In the day time other modes with far longer ranges seem to predominate. But there will always be a workable frequency for NVIS modes if you have enough freqeuencies available. (And ALE is a good tool for passively discovering this based on control station's beacon transmissions. If you hear something like turkey gobbling on HF when listening for SSB that's ALE.)
My sticking point is that I have absolutely no idea how NVIS works very near the poles. But at those locations working via longer range modes might be workable with several master stations in strategic locations around the world. The South Pole would be miserable to setup. The North pole has a good land ring around it that could support 1000 mile single hop communications in a pseudo-NVIS mode.
I'm not advocating scrapping the idea over the South Pole. I've not heard of any planes having difficulties let alone dropping down there on flights from Oz to South America. So it would be a lot of expense for modest reward. The plane would leave quite a splash on the white surface, I'd imagine. Surveying for it would not be nearly as difficult as the AF447 case.