Hi ChandraPrakash1: I did initiate such kinda thread in sajha, couple of weeks ago, asking assistance for flying via London. To my knowledge, you will be exempt if you are a green-card holder, or already had a valid US Visa (entry). If not, then, you have to apply for transit UK Visa, which you will either apply online or go personally in British Consulate (depends on where you located). The total cost for getting Transit Visa only is $78.00 from United States of America. I was planning via London, and applied online. Unfortunately, I have not gotten any reply. So, I called the British Embassy, and they want me to visit their place and apply personally. Since, it is a time consuming and not to mention an additional charge for my trip to back home, so I decided, why not just save that bucks and look for some other better options. Fortunately, I did find the nicest offer, which is via Paris. That was a piece of cake for me. Well, if there are other better option, so why should we waste our time and energy. Hope this information will assist you to some extend. Have a safe trip..... SuvaChintak Quest