777236ER From , joined Dec 1969, posts, RR: Reply 3, posted (12 years 4 months 3 days 15 hours ago) and read 1773 times:
At BA it's 4, 1, 2, 3. Engine 4 powers the primary braking source, that's why it's started first. Engine 1 powers the secondary braking source and engine 2 powers the reserve braking source. Engine 3 doesn't power a braking souce, that's why it's ofter shutdown after landing.