Standard notice is 2 weeks. Don’t ever turn down a job because you were worried about staffing the airplane. I quit a job on the spot one time and immediately took position in a new job. Not your typical situation but we were both done with each other and it was best to call it quits.
Take care of you first. Do you think if the flight department were to downsize and needed to cut your position, they would honestly be worried about giving you enough time to find a new job?