What I don't get is why airlines insist on bundling emergency telematics along with position tracking. It massively complicates what otherwise is a pretty simple problem. It feels like that description of the Bradley Fighting Vehicle out of the Pentagon Wars movie.
With a box the size of a Big Mac, at <$1k per unit and about $100/month in data costs, you could deploy an off-the-shelf industrial grade tracking unit that would transmit location/speed/altitude every 10 seconds whenever the unit is powered. All it would need would be a power supply. This would neatly solve the "where the heck is the plane" problem, globally, for a fairly trivial cost.
I realize that finding a spot on the plane to mount it, verifying aerodynamics, figuring out how to wire it in, testing, doing the work across a fleet and managing all that data all end up costing a lot more than the equipment, but given the costs being quoted for some solutions in the articles that have been coming up, it really seems like the airlines could have a big PR win by paying for it with petty cash out of their marketing/advertising budget.