Ativan. Of the three choices available it's the one best suited to treat anxiety. Ambien is a sedative. Flexeril is a muscle relaxant/anti-spasmodic. Because the flight is short you might consider half of your usual dose.
Ignore the recommendations about mediation, soothing music, ear plugs, talking to your neighbour and the other new-age solutions being offered here.
Pharmaceutical companies invest billions of dollars developing products for situations such as yours. Use as directed and only when necessary.