So the pico cell has to re-format the data so the delay through the satellite link doesn't screw up the GSM timing?
Makes me remember what the acronym ISDN really meant - I Smell Dollars Now!
But there's no reason if you spend enough money on the aircraft equipment, you can't fix the problem. You can then CHARGE - how much before the use dropped off too much would be interesting, but something between €1 to €1.5 a minute would probably fairly rapidly recoup costs. However, when you use a satellite, latency is a problem, which is why overseas telephone calls use fibre optic undersea cables. That's why you want a direct connection to a ground network.