On Aug 8, 7:08*am, "
wrote:
What is the pattern and which service is better to take to terminal 3?

From the central area it's as follows :-

Every 10 minutes - Hatton Cross - T123 - T5
Every 10 minutes - Hatton Cross - T4 - T123.

The trains serving T4 pause for 8 minutes at T4 before heading back to
London via the loop and T123. Depending on how pressed for time you
are then it is probably best to take a train for T5 and it will go
direct to T123. If you can tolerate an 8 minute wait at T4 then any
train showing Heathrow as a destination is fine. If you are in a
hurry and catch a train serving T4 then get off at Hatton Cross and
wait for the T5 train that should be following 5 minutes behind.

--
Paul Corfield
via Google