How many of the world's major airlines operate mixed fleets of Airbus and Boeing aircraft and why? Wouldn't it be much easier to consolidate to one brand of aircraft rather than operating such a diverse fleet as let's say NW does?
Also, I know US operates A330s and 767s. Do they have plans to retire or sell off their 767s? It seems that these aircraft are at least similar in performance, so why have airplanes of similar use. US seems to be the strangest fleet, with 737s, 319s, 320s, 757s, 321s, 767s and 330s.
What other airlines in the world have such diversity and are there plans for the airlines I've mentioned above, as well as any others, to retire these rather new planes? Are they headed somewhere else and what are you ideas on where....