Airline alliances

For travelers, the most obvious effect of airline alliances is codesharing whereby one airline will sell a seat on a flight with its own flight number, but the flight is performed by a different airline. (Note that not all airlines are part of an airline alliance, and not even all airlines within the same alliance do codeshares with each other.)

Although many airlines in an alliance have subsidiaries, the subsidiaries are often not members of the alliance which the parents are part of.

Oneworld is the smallest alliance counting by the number of airlines. The member airlines are spread evenly around the world, so it is a workable option when planning a long multi-point trip such as for a round the world flight. It was the first alliance to introduce interlining e-tickets.

SkyTeam is the latest large-scale alliance to be formed. It has a particularly strong network in Europe.

Star Alliance is the world's largest airline alliance.

Cooperation includes seamless code share flights and baggage interlining and, as a new trend, an increased degree of co-location in airport terminals.

Members of any Star Alliance frequent traveler program (FT) can credit miles or points flown in many booking classes on any Star Alliance operated aircraft.

"Gold" Star Alliance FT members get an extra 20 kg or "piece" of baggage; reciprocal access to most Star Alliance members' lounges; priority boarding and priority wait listing.

Value Alliance is an alliance of low-cost Asia-Pacific carriers.

Vanilla Alliance (French: Alliance Vanille) was created to improve air connectivity within the Indian Ocean region.

In some countries (especially those with extensive high speed rail networks) there are also cooperation agreements between airlines and railway operators, offering trains as a code-shared "flight" or other benefits to travelers. For more on the topic see rail air alliances.

Main article: Frequent flyer programmes

You should choose your Frequent Flyer airline in an alliance carefully. Although you may think it is intuitive to join the airline you fly most, you should be aware that privileges offered are often different and frequent flyer points may be more generous under a different airline in the same alliance.

By way of example, to reach Star Alliance Gold status (affording you priority wait listing and boarding, extra checked baggage allowance and use of lounges even when flying on any Star Alliance economy flight) requires only 20,000 miles in one year with Aegean Airlines' Miles&Bonus program, but some other member programs require 50,000 or even 100,000 miles in a year to be flown before awarding Gold status.