Airports are fascinating places. Many are simply launching points for travelers to fly near and far while others are major hubs of connectivity bridging cities in a network of global pairs that can boggle the mind. With new aircraft like the Boeing 787 Dreamliner and double-decker Airbus A380 offering flights between cities that once required connections, this is a great time for airport planners looking to secure new flights.

The size and scope of airports can be a subject of curiosity for many, which is why we want to explore some popular questions that circulate around these meccas of transportation. Some of the information just might surprise you.

1. What makes an airport “international”?

Even if your favored runway does not host regularly scheduled flights to foreign lands, it can still be dubbed an “international airport.” An international airport has customs and immigration facilities that accommodate commercial or private flights. Even small airports might have these facilities because they accept international cargo or private aircraft coming from other countries. The next time you pass through a small airport that is listed as an international facility, you’ll know why!

2. How do airports get their codes?

Surely you’ve heard jokes about airport codes like FAT (Fresno, California) and HEL (Helsinki, Finland). Airports don’t get to pick their codes, and they are hard to change, too. This can be a source of annoyance for airports that are labeled as serving multiple cities (especially when taxpayer funds go toward supporting a facility), but the code does not reflect that (for example, PHX serves Phoenix/Scottsdale and GSO officially serves three cities (Greensboro/High Point/Winston-Salem). The International Air Transport Association (IATA) is responsible for assigning the codes, and they can vary from being common sense to quite creative, as you can see. Chicago’s ORD is named for what was once known as Orchard Field, and MCO (Orlando) was formerly the site of McCoy Air Force Base. There’s also CVG, which is the code for Cincinnati; the airport is actually located in Covington, Kentucky (get it, CVG?).

3. What really qualifies as the world’s busiest airport?

There are two ways to measure the world’s busiest airports drafted by Airports Council International: passenger movements (the number of passengers who depart from a specific airport) and aircraft movements (the number of planes that take off from a specific airport). Atlanta Hartsfield Jackson International Airport has taken the top prize for having the most passengers each year since 2000. When it comes to aircraft movements, both Chicago O’Hare and Atlanta seem to compete for that title each year.

4. Why are there sometimes multiple flashing lights going off across the roof of an entire airport terminal?

We are not referring to lights used to guide planes into the gate. Occasionally, there are additional lights (colors can vary between airports) that flash for a short time, indicating lightning in the area. When the tower notices lightning, it is common for the ramp area to be closed, meaning ground crew must seek shelter inside for their safety. It is also necessary for fuel trucks to be repositioned to avoid lightning strikes. These flashing lights are an indication to ground crew that the ramp has been closed; they also can be an indication of impending delayed flights because aircraft cannot me marshaled into the gate and bags cannot be loaded or unloaded.

5. Why is the person next to me at the gate drinking a beer? Isn’t that illegal?

You might be surprised to learn that some airports have property-wide liquor licenses—meaning it is legal for someone to walk around the terminal with a drink purchased at the airport bar. Both Memphis and Nashville airports currently offer this; others are looking into it as a way to boost sales. Don’t try it on your own unless you know the airport offers it!

6. What is an amnesty box?

These are often found before the customs exit for travelers to discard things like fresh fruit, meat, plants, and vegetables that traditionally are not permitted to cross international borders. Many island airports have these because transporting an infected item could cause harm to the island’s ecosystem. Auckland, Honolulu, and Sydney are just a few that have them. But for as many airports that do have them, there are many that do not. This creates a catch-22 for international travelers who may have forgotten a spare apple in their bag with nowhere to discard it before hitting the inspection line (garbage cans and warning signs are not universal in arrival areas). Beware the hefty fines that unflinchingly harsh border patrol agents (and their roving canines) can throw at you for accidentally bringing in a piece of fruit. And it’s not always about food. Colorado Springs has an amnesty box for travelers to discard marijuana before leaving the state.

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