Airport classification has gotten complicated with all the terminology and bureaucratic categories flying around. I got curious about this a while back when someone asked me the difference between the airport I fly out of for work — a big commercial hub — and the tiny airstrip near my uncle’s property where guys fly Cessnas on weekends. Turns out there’s an actual system for this, and it’s more interesting than you’d expect.
The FAA breaks airports down into three main types: Commercial Service Airports, Reliever Airports, and General Aviation Airports. Each one serves a different purpose, handles different kinds of traffic, and operates under different rules. Let me walk through them.
Commercial Service Airports
These are the ones most people think of when they hear the word “airport.” JFK, LAX, O’Hare, Atlanta Hartsfield — the big names. A commercial service airport is defined as any airport that receives scheduled passenger service and boards at least 2,500 passengers per year. That’s the minimum threshold, and obviously the major hubs blow way past that number.
Within this category, there are further breakdowns. You’ve got “primary” airports, which have more than 10,000 annual passenger boardings, and then those get sliced into subcategories — large hubs, medium hubs, small hubs, and nonhub primaries — based on what percentage of total national passenger boardings they handle. A large hub like O’Hare accounts for a huge share of national traffic, while a small hub might serve a mid-size city with a handful of carriers.
Then there are “nonprimary” commercial service airports, which have between 2,500 and 10,000 annual boardings. These are typically smaller regional airports that still offer scheduled service but at a much lower volume. You might find one or two airlines operating out of them, maybe connecting to a nearby hub.
Probably should have led with this, but the reason these categories matter is funding. The FAA distributes money to airports based partly on their classification. Bigger airports with more passengers get different funding formulas than smaller ones. So when an airport crosses from nonprimary to primary status, or moves up a hub category, it can mean a real financial shift. It’s not just labels for the sake of labels.
Commercial service airports also have the most infrastructure — control towers, ILS approaches, multiple runways, full fire and rescue services, the works. If you’ve ever watched those behind-the-scenes airport documentaries, they’re almost always talking about commercial service airports. The logistics of moving thousands of people and hundreds of flights a day are genuinely impressive once you start paying attention to it.
Reliever Airports
This is the category I didn’t know about until I looked into it. Reliever airports exist specifically to reduce congestion at nearby commercial service airports. The FAA designates them in metropolitan areas where the main airport is getting overloaded with general aviation traffic — small private planes, flight training, charter flights, that kind of thing.
The idea is pretty straightforward. If every small Cessna and training flight is trying to use the same runways as commercial airliners, things get backed up fast. So the FAA identifies nearby airports that can absorb that lighter traffic, and designates them as relievers. This frees up the big airport’s runways and airspace for scheduled airline operations.
Reliever airports are usually smaller, with shorter runways and fewer services, but they’re well-maintained and have the facilities that general aviation pilots need — fuel, hangars, sometimes a small FBO (fixed-base operator) with a pilot lounge and basic amenities. Some of them are surprisingly nice. I visited one outside of Dallas with a friend who flies recreationally, and it had a little cafe on the field where you could eat lunch and watch planes take off. Not a bad setup.
There are a few hundred reliever airports across the country, mostly clustered around major metro areas. They don’t get the same level of funding or attention as commercial service airports, but they play a real role in keeping the air traffic system functional. Without them, the big airports would be even more congested than they already are, which — if you’ve flown through O’Hare on a Friday afternoon — is saying something.
General Aviation Airports
This is the biggest category by sheer numbers, and also the most varied. General aviation airports are basically every public-use airport that isn’t a commercial service or reliever airport. There are thousands of them across the U.S., and they range from well-equipped regional fields to tiny grass strips in rural areas.
General aviation covers a lot of ground — private recreational flying, agricultural spraying, flight training, corporate jets, medical transport, aerial surveying. If it’s not a scheduled airline flight, it’s probably general aviation. These airports are the backbone of that activity.
The FAA further classifies general aviation airports into categories like “national,” “regional,” “local,” and “basic,” depending on how much traffic they handle and what kind of activity they support. A “national” general aviation airport might handle corporate jet traffic and have instrument approaches, while a “basic” one might just be a paved strip with a windsock. I’m not exaggerating — I’ve been to one where the “terminal” was a metal shed with a vending machine. It had a certain charm, honestly.
What I find interesting about general aviation airports is how important they are to smaller communities. In rural areas, the local GA airport might be the only air access for a hundred miles. It serves medevac flights, delivers mail and cargo, supports local businesses that depend on air transport, and provides a base for flight schools. Close one down and you can really feel the impact on the surrounding area.
They also don’t get a lot of love in terms of funding or public attention, which is a shame. Most people drive past their local general aviation airport without even realizing it’s there. But those little fields keep a lot of the country connected in ways that aren’t obvious until you start looking into it.
So Why Does Any of This Matter?
Understanding the three types helps you see the aviation system as a whole instead of just thinking “airport equals place I catch a Delta flight.” Each type handles a different layer of air traffic, and they all work together — or at least they’re supposed to. Commercial airports move the masses, relievers keep the small planes from clogging up the big airports, and general aviation fields serve the rest of the country’s flying needs.
I started looking into this out of casual curiosity and ended up finding it genuinely interesting. The system is bigger and more layered than most people realize, and each type of airport has its own character. Next time you drive past a small airfield with a few hangars and a single runway, you’ll know — that’s a general aviation airport, and it’s doing more than you think.
