When turbulence hits, let your shoulders drop, relax tight muscles, and release facial tension. Remind yourself to breathe slowly, and focus your attention on your beath. Make the out-breath two times longer than the in-breath. This will immediately calm you. Repeat this mantra: "I am calm."
Travel Yoga: Stretches for Planes, Trains, Automobiles and more!, Darrin Zeer, pg 50