London Heathrow Airport

Code-sharing: Seams are showing

If you buy a ticket on British Airways flight 1541 from Chicago to London, you might decide to show up for your departure at O'Hare's international terminal 5, where BA operates its Chicago flights. If so, you might miss your plane, because BA flight 1541 is actually operated by American Airlines and leaves from American's area in terminal 3, some distance away. And if someone tries to meet you at BA's terminal 5 in Heathrow, you'll be standing there at American's baggage claim in terminal 3 wondering where your host is. It works the same way for American, too; its flight 6194 is actually on BA flight 294.

Welcome to the wonderful world of code-sharing, a system in which one...