If we assume that the HQ represents a country's Command and Control, and that sector bars represent tactical intelligence distributed from the HQ, then destroying the HQ SHOULD disable the sector bars for the entire country. If we assume that inflight radar dots are information from ground controllers also distributed from the HQ, then killing HQ should also disable inflight radar.
So far, the current system is correct IMO.
The only change I would make, would be to make LOCAL radar for a particular field available in that field's tower, even when HQ is destroyed. With the HQ destroyed, there would be no country-wide inflight information, but there would be local, ground -based information from WORKING radar towers.