Originally Posted by
kappa
Such flight following position information can be provided by an automatic, un-interruptible upload, once per minute, of GPS-derived latitude/longitude, altitude, heading and speed data, on a persistent VHF link when over-land and via a persistent satellite link when out of VHF range, over water. That is not a lot of data, even for what are 30,000 daily overwater airline flights worldwide.
Saying 'that's not a lot of data' is rather like saying you can stick a $200 SSD in the CVR and record for years. It's not a lot of data on your home broadband, but it's a lot of data for a legacy SATCOM system designed decades ago.