Terminal Map - London Heathrow International Airport

Check to see if you're on a codeshare flight
Even if you have a connecting boarding pass issued by American Airlines with an AA flight number, your connecting flight may be on a oneworld® or codeshare partner. To find out if you're on a partner carrier, look for the words, "Operated by…" on your ticket. For connections, just follow the purple "Flight Connections" signs for the free bus which operates every five minutes.
Admirals Club