The relation between Airbase Status vs Sorties Fragging can be describe from either point of view.
Status level of Airbase is driven by the status of its Features* (Runway, Tower, Fuel Depot, Buildings, ...)
The more buildings (Features) are destroyed, the less is the status.
Once sufficient features are destroyed
status will be 0% and the Airbase will "shutdown"
HQ will not frag new Sorties, but planned sorties will continue
unless Runways are destroyed
If the Runways are destroyed
the Airbase will "close"
all planned Sorties will be canceled
no new Sorties planned until Runways are repaired & Airbase Status become higher than 0%
Status level of AirBase drives the Sorties Fragging :
When it comes to 0%, the AI HQ stop Fragging new Sorties, except for Interception Flight (if the runway itself is not destroyed).
But you can still manually plan Flights/Packages if there is sufficient Aircraft in the Squadrons (if the runway itself is not destroyed).
All Fragged Sorties will be launched :
Regardless of the actual reported Aircraft remaining in Squadrons.
Until the Runways are destroyed.
When Runways are destroyed
All Fragged Sortie are deleted.
Manual planning is no longer possible.
The more buildings destroyed, the more resources are needed for reconstruction
Sources : https://forum.falcon-bms.com/post/370651 (@Atze 0, @tiag, @CheckPoint)
* See Objectives & Features for more details