Airline Employees
The wages of nonresident flight personnel (e.g.pilot, copilot, flight attendant) are not taxable by California unless more than 50% of the individual’s scheduled flight time is in California.
If more than 50% of the scheduled flight time is in California, wages are apportioned to California based on the ratio of time spent in California to the total scheduled flight time.
Flight personnel who are California residents are taxed on all wages received regardless of where the flight time is spent.
https://www.ftb.ca.gov/forms/2013/13_1031.pdf