Originally Posted by
XSBaggage
But then why do they still insist on mixing their fleets? For example BA have both 787-8s and 787-9s, but they have an A350 order coming soon too? I always thought the sensible thing was to have as few types to allow crew commonality.
Fleet commonality is a cost driver, that's true.
But so are lots of other things, including the ability to put a squeeze on manufacturers' prices by also ordering some of the competition's product.