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I am going on 6th Aug to Gainesville, FLorida, USA. My flight itinerary is as follows: Mumbai to Heathrow - Jet Airways, Heathrow to Miami - American and Miami to Gainesville - American. Transit time at Heathrow is 3 hours. I will be arriving at Terminal 4 and will be departing at Terminal 3. Since Jet and American have a codeshare I guess my baggage will continue checked in and i dont think I have to recheck it. I have a valid F1 visa. Do I need a transit visa? PLs help.