Do they know for sure it stopped transmitting? The problem with ADS-B is that it is lost over large ranges, like oceans. A space-based system to track aircraf

Do they know for sure it stopped transmitting? The problem with ADS-B is that it is lost over large ranges, like oceans. A space-based system to track aircraft globally is currently in the works. http://www.aireon.com/Solutions/TheGlobalAdvantage http://www.aireon.com/Solutions/TheGlobalAdvantage edit: Here is an informative ADS-B coverage map I found: http://uk.flightaware.com/adsb/coverage http://uk.flightaware.com/adsb/coverage