California Code, Revenue and Taxation Code - RTC § 1155

(a) If the aircraft takes off in one taxing agency which is entitled to tax (within the meaning of the preceding sentence) and lands in another agency which is entitled to tax, the flight time between such taxing agencies shall be allocated one-half to each such agency.

(b) If the aircraft arrives from out of state or leaves the state, the flight time from or to the state boundary shall be allocated to the taxing agency entitled to tax in which the aircraft first lands or last takes off, as the case may be.