Originally Posted by PhlyingRPh
Your parents as Indian citizens will require a Direct Airside Transit Visa to transit through a U.K. airport. This will allow them to either remain on a plane that is enroute to the U.S. or connect to another flight while remaining airside.
Sorry, but that is 100% incorrect for the scenario posted by the OP!
See:
http://www.ukvisas.gov.uk/servlet/UK...location=India
You asked if a national of India needs a visa to pass through the UK in transit.
Yes, you need a Direct Airside Transit (DAT) visa, unless you qualify for exemption because you hold one of the following:
- a valid visa for entry to Australia, Canada, New Zealand or the United States of America and a valid airline ticket for travel via the United Kingdom as part of a journey from another country or territory to the country in respect of which the visa is held;
- a valid visa for entry to Australia, Canada, New Zealand or the United States of America and a valid airline ticket for travel via the United Kingdom as part of a journey from the country in respect of which the visa is held to another country or territory;