The aviation industry is quite fascinating. There are codes and secrets that only flight attendants and pilots know about, and random facts that are only familiar to those who are in or work for the industry.

But, there are more important things to know, including terms that can help you as a traveler, even if you don’t fly that often. Let’s take a look at each one.

Legacy Carrier

Legacy carriers are airlines that provide better in-flight service, features, and rewards that low-cost carriers do not. For instance, Singapore Airlines, British Airways, United and Qantas are considered legacy carriers. However, in order to be considered a legacy carrier, the airline has to have been established before the 1978 Airline Deregulation Act.

Interline Agreement

Airlines have interline agreements that allow them to manage passengers traveling on itineraries consisting of more than one flight on different airlines. This allows travelers to travel easier with their luggage. Without it, you would have to pick up luggage at every destination (even if it’s just a transfer) and re-check it back in. Interline agreements are only between non-low-cost airlines (i.e. United, Qantas, Emirates, etc.).

Open-jaw Ticket

There are three different types of open-jaw tickets. The first is a destination open-jaw, where a traveler goes to one city and flies back to the same city from another city. An example of a destination open-jaw ticket is flying Chicago to Paris one way, and then back to Chicago from Dublin (instead of Paris). The second type is an origin open-jaw ticket, where the return trip is to a different city. An example of this is flying from Chicago to Paris one way, and then the return is Paris to New York. The third type is called a double open-jaw ticket, where the destination and origin cities are completely different going there and coming back. An example of a double open-jaw trip is Chicago to Paris one way, and the return is Dublin to New York.

Ancillary Charge

An ancillary charge is just a fancy name for additional ticket add-ons that are not included in the base price. This can include baggage fees, drinks and snacks, seat selection, etc. Low-cost carriers rely on these ancillary fees to help them profit off the cheap airfare. Even airlines such as United and Delta, for instance, have ancillary fees for meals purchased in-flight, entertainment and baggage check-in.

Pink-eye Flight

There’s a red-eye flight, and there’s also a pink-eye flight, which is almost the same. A pink-eye flight is a flight that lands right around the time the clock strikes 12am. If a flight is scheduled to land around 1am, it is red-eye.