How do humanitarian flights arrange special permissions to fly when ATC isn't available? In natural disasters, transportation infrastructure is often among the first and most critical of public services to be disrupted. Not coincidentally, it's also a time that tends to see small airports become vital intake for international support.

If aircraft acting on humanitarian concerns, say a commercial airliner loaded with doctors and medicine, wants to land in a major city affected by a natural disaster where radar is destroyed, ATC is non-functional, and runways are... surprisingly clear, what is the procedure for arranging landing?

In practice, do humanitarian support just approach, land, and deal with the consequences later?
In the U.S. at least, HADR doesn't launch aircraft until a crisis aka disaster has been identified, even if at launch they don't yet know if the problem is lack of potable water or civil unrest over rigged elections.

An already flying commercial airliner won't have a glut of doctors and medicine unless it's been chartered for an already identified crisis, so it's unlikely to divert to this one.

If, after an identified disaster, an aircraft flies there to assist:


A helicopter doesn't need ATC support to land in an off-airport parking lot, of which a major city would have many.
A fixed-wing aircraft, needing an approach path, lacking ATC response, would revert to non-ATC protocols, just like at a small Midwestern grass strip or an Alaskan inlet.  VFR.


Non-aero analogy:  fire trucks and ambulances don't fret over parking tickets.