Ana Forrest, founder of Forrest Yoga Institute in Santa Monica california, is a world traveler. She says that plane travel is one of the most stressful environments and has found some yoga techniques that can be done aloft to reduce that "no room to move, no food to eat, crying baby, dirty lav, rain delay, mile high stress". On her list of recommendations:
Deep breathing exercises and subtle poses you can do while seated. (Can you put your left ankle over your right thigh and bend forward?), The Spinal twist - done by turning and grabbing the back of your seat or the arm rest and take 5 to 6 breaths. For the expert, try bringing your leg over your shoulder in the Krounchasana position. Just be sure to stay in your own personal space, please.
Read more about Ana at her website - Forrest Yoga