How do I convince my parents to let me fly alone to see my aunt ?

After my semester ends, I would like to fly up to San Francisco from Orange County to see my aunt. I will have to fly alone for a flight that lasts 1.5 hours. I am 21 years old and I have the money to afford the plane ticket no problem. My aunt is a trusted adult. The only real issue is the actual flight. My aunt will pick me up and my parents will drop me off. I can't drive there because I do not have a car and there is no direct train route there.