Unusual as it is for me to do more thanone post a week, I had a question come in that I wanted to answer in this forum as I suspect others may be interested also.
As I am going to give some specific postural suggestions in this post, this is important: If you have specific health issues, or injuries, please do not start doing a yoga practice until you have talked to your health practitioner.
The question was what kind of yoga asanas can be done during a 5 hour airplane flight. My feeling though was that I would like to respond with some general thoughts on yoga while traveling, as well as some specific postures. In a way, the specific postures are easier.... you can find lots of pictures and photos and clips online. In a way though it is like stress reduction.... you can relieve stress during a stressful episode for example by going for a bike ride and decreasing circulating catacholamines, and resetting the balance between the parasympathetic and sympathetic nervous systems, but you could also learn techniques to block that imbalance at other points in its course, for example by developing cognative strategies to use when confronted with a stressor.
This is by no means an exhaustive list, but just some off the cuff ideas.
When planning a trip consider what your options will be for physical activity, as well as down time when you get there. If you are going for a walking tour of Napa wine country you will probably have good opportunity for physical activity, but will probably want to think about leaving some free time just to sit with a book. It is a bigger part of yoga to balance your life, than necessarily having to make yourself crazy about getting to the mat. If, however, you have the time, and actual yoga is a big priority for you, look before you go for local places you can do yoga. It should not be too hard to do when you are there, but knowing in advance, for example that there is a Kripalu studio in the area, and you do not have one near you, and have always wanted to try that style, knowing they offer classes at a certain day and time might help you to plan. And find out whether they provide mats, as you may not be bringing one. But if the plan gets ditched when you get there, don't sweat it. Being flexible in yoga is not just being able to do a deep back bend.
If you are leaving in the evening try to do a walk, or a workout, or a yoga session earlier in the day. If you are leaving in the morning do it the day before if at all possible. If you are an anxious traveller it will help, and if you are travelling by plane in coach it will also help.
One pose I recommend to do at least the day before travel is viparita karani. You lay on the floor with your legs up the wall. You can keep a small bend in the knees, you can pad under the hips. If you have balance issues, or osteoporoses please take care getting up and down. If you are pregnant past the first trimester you should consult the current ACOG guidelines for exercise, and I would advise modifying this position with cushions, so that you are almost sitting upright, and your feet are raised to a comfortable level. This pose helps with venous return. I have chronic lymphademia in one leg, so I find if I do this before and after travel it helps with the swelling I otherwise see with enforced sitting.
You might like to try a seated, or chair yoga class. Some of the work done in these classes are very good for modifying for use in a plane, or as a passanger in a car. (do I need to say do not do yoga while driving?)
You might like to have some yoga appropriate music on your ipod. Great for doing a pranayama practice, or meditating. I am very fond of Anugma, and of Steven Halpern. There is also a quite wonderful CD called 'Spa Dreams', but ITunes, or your ap store, or Amazon, or wherever you buy your music should have a listen before you buy function.
Also, try not heading out dehydrated. You can dehydrate over the course of days, so taking enough water (The mayo clinic suggests roughly 13 cups of total fluid (including water) for men, and 9 cups of total fluid (including water) for women, each day, keeping in mind that this will vary with different individuals, and with different activity levels, and with different climates. Caffeinated beverages will dry you out, so try to push the balance toward a bit more water if you like your coffee.
I would also suggest if you can you wear clothing that is not too restrictive. Clearly business travellers do not have as many options in this area, but if you are going to try to do some stretching, or yoga you will have more range of motion if you wear something comfortable. At least, if possible, wear shoes that easily slip on and off. If you can at least get your shoes off you can wiggle your toes, and rest your feet.
My next post will give you some specific ideas on what you can do while you are on your flight. (for my friend with the question, I will try to get back to the computer to post tonight, but if I do not stop now my family will not have dinner and my son is playing in a clarinet recital at our Philharmonic school... you can perhaps see why I do not post daily. That and I try to think clearly rather than just rush through.)