Hi There After going through your query I understand your concern. I would like to tell you that peripheral artery disease is a common circulatory condition in which narrowed arteries reduces the blood flow to limb which can cause claudication ( pain on walking) in some patients. Sitting immobile on long plane flights can slightly increase the risk blood clots in the legs. But your Father s flight is approximately of two hours that will not be an issue. Must tell him to get up and walk a little bit inside the plane whenever possible. You can also consult with his treating physician regarding this if any perticular precautions are required in his case. Hope to have been helpful. Kind Regards Dr. Navneet Bansal