Air Canada has codeshare partnerships with several airlines, including United, Lufthansa, Singapore Airlines and Swiss Air. The list of interline partnerships is even longer and consists of carriers that belong to the Star Alliance network and some independent airlines. Examples include Air China, Air New Zealand and Aer Lingus.
Codeshare partners allow Air Canada to ticket passengers using its airline-designation code, AC, on flights operated by the codeshare airline. For example, if a person is flying from Toronto, Canada, to a smaller airport in Germany, the itinerary might have three flight segments. The first two are Air Canada flights but the last connection is to a Lufthansa flight. In this situation, all segments show the flight numbers with the AC designation. The passenger itinerary shows that the last segment is a Lufthansa flight.
Interline partners allow each airline to issue tickets on the other's carriers, but the flight segments carry the designation code of the airline operating the flight. Looking at an itinerary from Canada to Asia, the segments on Air Canada planes are coded AC, while another may be operated by Cathay Pacific and be coded CX.
The Star Alliance network represents airlines that allow passengers to collect and use air miles for all carriers in the group. The interline designations work the same as for non-participating airlines, but the Star Alliance symbol is noted next to the partner airline segment.