Originally Posted by TravellingChris

What I find equally fascinating is "unfaithfulness"--where an alliance member pursues a codeshare relationship with a non-alliance carrier in order to serve destinations that the former doesn't. The problem arises when those same destinations are already served by a fellow member of the first airline's alliance. The whole idea behind international alliances is to partner with carriers across the globe in order to serve most destinations that a traveler could want to fly to, and to feed traffic to and from alliance partners for mutual benefit, rather than that of a third party.

A good example was the codeshare agreement with Cathay Pacific that Air Canada reached a few years ago--AC placed its code on onward CX flights from Hong Kong to destinations such as Manila, Bangkok, Saigon and Kuala Lumpur. However, each of these cities was already served by a Star Alliance carrier. For example, AC should have been feeding Bangkok-bound passengers to THAI at either HKG or NRT rather than Cathay Pacific. (The agreement was reached before AC started non-stop flights to BKK itself.) Manila-bound passengers should have been placed on ANA flights from NRT rather than CX ones via HKG. Indeed, the whole idea of an alliance is to give your fellow member airlines preference when routing your passengers to destinations you don't serve directly.

We see this again with AC's relationship with Emirates. There are plenty of onward destinations that Emirates serves (such as in the Middle East and Subcontinent) that AC doesn't. However, most of those cities are already served by Star Alliance carriers such as Turkish Airlines and Air India. Shouldn't AC be directing onward traffic onto their flights instead of those of non-member Emirates?