The warning is nearly useless. There's the sound indicating something, and then somewhere one of 100 fields starts flashing. Lack of information about incoming attacks helps to attack in a way that requires no fight.
idea 1) Flash bases when an enemy carrier is near. Ground observers would surely spot it and report it.
idea 2) Flash bases differently (different pattern) depending on the kind of attack. Planes/GVs within flashing range, flash as today. Ack damaged, 2 short flashes; town damaged 3 short flashes.