Sciatica Nerve Pain

I have had sciatica nerve pain which goes from my butt to my leg. I've been doing exercises to make it feel better. It's been workings and as long as I'm active it doesn't hurt. But when I sit on the couch it gets pretty bad. In a week I'm about to go on a 15 hr plane ride and not sure how I'm going to make it. Anyone had this before? Are there any tips or tricks to get it feeling better before or during the flight?