Question:
Is an air unit assigned to a naval patrol mission susceptible to being damaged from an airbase tactical bombing attack, or are they flying (that is, on a mission)?

Answer:
Air units assigned to naval patrol missions remain at their airbase until they fly a mission, so yes, they can be bombed on the ground. They might not fly any mission at all that player turn, so it would be a sick trick to allow air units to avoid being bombed at base simply by having them declare that they were on naval patrol.

Source:
TEM 53