I first heard about it because of this story: https://www.latimes.com/local/lanow/la-me-ln-kaufman-sailing-voyage-20140410-story.html https://www.latimes.com/l

I first heard about it because of this story: https://www.latimes.com/local/lanow/la-me-ln-kaufman-sailing-voyage-20140410-story.html https://www.latimes.com/local/lanow/la-me-ln-kaufman-sailing... I don't think it's a commercial system, but there is great cost in diverting a US Navy vessel for a search and rescue operation, though I suppose that is ideally the reason that they're out there in some sense. After just a touch more reading, it looks like the rescue locator beacon system is piggybacking on GPS and Galileo satellites for some functionality, but includes other satellite and ground based systems too. Pretty cool.