"milesh" wrote in message
...

Does the tube stop first at Heathrow's Terminal 4? Or do I have to
transfer to another tube from Terminal 1,2 or 3 across to Terminal 4?

After Hatton Cross the Piccadilly line does a loop, first to Terminal 4,
then to Terminals 1,2,3 and then back to Hatton Cross heading into London.
If you want to transfer from 4 to 1,2,3 it's easy; if you want to do it the
other way around then you either have to change at Hatton Cross and double
back or, alternatively, take the Heathrow Express from Heathrow Central
(T1,2,3) to Terminal 4. Transfers are free within the airport boundaries.

HTH