Re: Not a design flaw...
Since this vehicle is up in the air, I'd assume that radio was not obstructed, but merely out of range.
If this is the case, I would think that the craft should report with a low signal condition before a complete loss occurs.
If not, it might even be a viable precaution to deliberately turn down the signal so that it enters no signal mode before being truly out of range. The operator could then boost the signal to give it instructions to come home.
I'm a little surprised this military gadget doesn't have a satellite transponder for this sort of thing.