One of the best ways to establish that you are in a relationship or interested in a relationship is to drive her to the airport. If she has a trip planned and you can’t go or weren’t invited, then simply offer to take her to the airport.
Driving someone to the airport is one of life’s major pains. If you do it with a smile on your face then she will really understand your feelings for her. Don’t complain about traffic on the way up either, complaining, not that attractive.
Unload her bags for her also. You don’t have to walk her all the way to the terminal. You can say your goodbyes on the curb, just as long as you got her there is what counts. When she arrives back you can have a nice date and talk to her about the trip.