> a status report every two minutes or so would be technically feasible and not terribly expensive?
...but also not very useful. Two minutes is a long time when you're traveling at 570 MPH - in the event of a catastrophic explosion a plane could be on a perfectly normal flight path one minute and then gone the next, and you still have a vast radius to cover when looking for the wreckage.
Then do the update every 5s. You don't even need to do a full update, just coordinates, heading, altitude and speed. Still technically feasible, still not terribly expensive (seriously, ~80 bytes every 5 seconds) yet potentially very useful since you can pinpoint an aircraft's location to within less than 1/2 mile at any point during its flight.
...but also not very useful. Two minutes is a long time when you're traveling at 570 MPH - in the event of a catastrophic explosion a plane could be on a perfectly normal flight path one minute and then gone the next, and you still have a vast radius to cover when looking for the wreckage.