An initial hit with a 2000 lb LGB causes a mere 2.8% damage.
'Tis but a scratch! says the Black Knight!
And it is, except for the fire...
... that burns for the next four hours and ten minutes, consuming another third of the runway before it finally goes out.
Who knew vast flat slabs of concrete were so vulnerable to flame? Good thing it isn't normally exposed to heat sources like afterburner plumes! [:D]
I'd suggest making runways, taxiways, etc. unable to burn. I've had several scenarios where I've burned out enemy airfields, without needing a follow-up raid, and that really shouldn't happen.
