Back up radio systems and redundant engineering. You have thought that this would have been started as a severly overt plan since the 60's, but I guess not.
Airborne relays, repater systems would not be a plausable explanation to a national catastrophy. The need for aircraft would be to significant, as well as needing antennas for multiple radio systems and radio bands / frequenys and ecetra.
Civilan and radio hobbiet, ham radio operators could mroe than well enough handle esential tasks as far as radio relay in most locations. The exception would be large metrolpolitian agencys like Detroit, Los Angelas and others.
Radio and communication administrators for Public Safety agencys need to look at this and look hard. Planning, devoloping, and fabrication of back up radio systems for their agencys concerned. Receiving input and ideas from subordiantes, agency heads( Fire& L/E ) , and radio service folks. A national emergency, catastrophic event, or an act of terrorism. Me. If I was a Department Administrator and had the funds, I would set one up for my agency. Somehow, but I would do my best to make it happen. I would take care of my own folks instead of depending wholly on county / state radios repeaters.
Can you have a rural backup repeater station, where the only thing you have to do is raise a portable antenna system, or have a winch / motor system to raise a moderately tall antenna system? The antenna hidden, or lowered to prevent damage? How about a backup repeater system, antenna and all, where all you have to do is turn on the repeater?
Is a company, or corporate entity willing to allow you to use their high rise, elevate building as a repeater location? Install the repeaters, keep the antennas hidden, raise them when needed. Gee whiz, how tall does the repeater antenna have to be on a high rise, or elevated building / structure?
Aircraft would be costly, and could not cover an entire area, and many would be needed in a multi-jurisdiction Multi-Casualty event / national disaster.. Weather could play a hazzard, and might hamper Public Safety communications due to lighting, clouds , rain - or other radio signal barrier. Public Safety agencys are not the military. Radio signals from portable radios might night reach the aircraft, whom is at at altitude to cover a large area, or at an altitude to prevent mountainous terrain from being a barrier for teh area they are covering.
Leave it to the Government and Homeland Security to screw up radio communications.
FF - Medic !!!