It looks like AA 174 (RDU-LHR) moves to 8:05 PM starting the end of march permanently. The inbound AA 173 is still on the same schedule, so the 763 will just sit longer at RDU as it flies no other routes from RDU.

Does anyone know the reason for this? As an RDU traveler, this makes it harder to catch early connections in LHR. It's possible they are trying to route people from PIT/DCA to LHR (you pick up an extra flight for each by moving the flight out two hours). But you can route PIT/DCA traffic through PHL/JFK, and this seems counter to their cornerstone strategy. There must be another reason... Maybe something with timing 763's at LHR...

CORRECTION: AA174 moves back next Nov. So the changes is from late March - early Nov. Basically, it maps to British Summer Time (BST).