What it takes to be an air traffic controller at the world's busiest airport

• In 2019, air traffic controllers at Atlanta Hartsfield-Jackson International Airport, the world's busiest airport, directed 909,000 flights through takeoff and landing.
• The airport's 58 controllers are responsible for the safety of hundreds of millions of passengers on board those planes.
• Controllers have to contend with weather, tight schedules, and knowing any mistake they make could cause a ripple effect of delays across the country.
• Pre-pandemic, in February 2020, Business Insider went up inside the tallest air traffic control tower in America to see how training, technology, and diligence make this job possible.
• Since Business Insider's visit, the tower has closed to all visitors and implemented social distancing and a mask requirement. The airport has seen just 60% of last year's air traffic volume, with 1,500 takeoffs and landings a day.

Following is a transcription of the video.

Paul Stearns: All right, Delta 2452, continue. Juliet and Mike de Lima. Charlie, monitor the tower, 123.85.

Narrator: 400 feet above Atlanta Hartsfield Airport, air traffic controllers oversee the skies of the world's busiest airport. Firing off commands to pilots...

Stearns: Delta 393, Atlanta ground runway 27R, taxi via Lima, hold short of taxiway Dixie.

Narrator: They juggle 2,600 landings and departures a day, in all kinds of weather.

Rally Caparas: You can go upstairs and you can look out of that window and you can see nothing at all, and still have movement taking place on your airport.

Narrator: But air traffic controllers can't mess up. Not only are lives on the line, but...

Caparas: This is the ultimate in domino effects. If something's going wrong in Atlanta or if there are major delays, it disrupts air travel all throughout the country and parts of the world.

Narrator: Back in February, before COVID was named a pandemic, Rally took us up inside the tallest control tower in the country to see what it really takes to be an air traffic controller. This is Atlanta Hartsfield-Jackson International Airport, and these are its five runways. And here's the control tower. It takes a rotating staff of 58 traffic controllers to keep the airport running. Pre-pandemic, they directed 909,000 flights through takeoff and landing each year. These controllers are responsible for any planes inside Atlanta Hartsfield's airspace, five miles out and 4,000 feet above the airport. Once a plane enters Atlanta's territory, air traffic controllers are in charge of communicating with pilots over radio. They direct pilots in the air through safe landings and pilots on the ground through takeoffs. The goal?

Caparas: Efficiency, efficiency, efficiency. What can you do to help us be more efficient? Well, one thing that we're not gonna do is make sure that you compromise safety in that equation.

Narrator: But the job isn't easy.

Caparas: There's a lot of dynamic decisions. If an aircraft is coming in to land and they have to go around because of an unstable approach, the weather didn't cooperate, they couldn't get the runway in sight, you have to be ready to make a decision.

Narrator: To become a fully qualified controller, it can take up to five years of classroom, simulator, and on-the-job training. But if they make it, the average controller in Georgia makes $145,000 a year. A job in Atlanta's tower is one of the most coveted ATC positions in the US. Candidates go through a rigorous hiring process, which can take...

Caparas: Somewhere just under a year. We're getting closer to six to nine months.

Narrator: Once they've been hired, incoming controllers start on the simulator.

Stearns: So, any new controller that would come here, they would initially come here and do bookwork, and then, following up with the bookwork, they would come into the simulator room.

Narrator: A new controller will do multiple pass-fail scenarios, but on the simulator, they'll have fewer planes to juggle than the real deal in the tower.

Stearns: Then they'll have an evaluation. And then if they pass that evaluation, they can head up to the towers.

Caparas: We have two controllers working there today. One of them is in training. There's never really a slow period to speak of.

Narrator: Though, air traffic always picks up in the summer and days before and after holidays. But whether it's Christmas Eve or just another Tuesday, controllers have to stay focused.

Caparas: I don't know that we want people to be comfortable. We want people to be on edge; we want people to be at the top of their game.

Narrator: Controllers have to remember and monitor up to 30 planes at once. That's a lot to think about, especially since studies show the human brain can only handle seven things in short-term memory at a time.

Stearns: I had about 25 to 30 aircraft all on my frequency at one time. They were all taxiing out for departure. But once I said, "Monitor the tower, 123.85," that's when they got off my frequency. So, you know, at one time you could have a lot. Then, one minute later it could be all gone.

Narrator: The job's so mentally draining that the Federal Aviation Administration allows controllers to work for only two hours before they're required to take a break. To help make their work easier, controllers' jobs in the tower are highly specific. Each runway is assigned either takeoff or landings.

Stearns: That controller is just focused on that runway, that specific runway and that specific runway only.

Narrator: The controller who clears planes for takeoff or landing is called the local controller. There are two or three of them in the tower at once.

Caparas: This gentleman's working what we call local five, and local five is handling, at the moment, all the arrival aircraft coming in from the east.

Narrator: Then there's the ground controller. This guy focuses on directing traffic on the ground, telling planes which runway to taxi to. So in the case of an approach and landing, it might start with the local control saying this to the pilot.

Caparas: It'll be, "Delta 222, runway 8 left, wind calm, clear to land." We'll turn it over to the ground controller. As they exit, "Delta 222, contact ground, 119.2." They'll go over to ground control. Ground control will tell them which direction to taxi to get them over to the ramp.

Narrator: Controllers have universal rules to follow to make sure everyone is safe. First, there's the lingo.

Stearns: All right, 1123, taxi to ramp, keep it moving, traffic behind you, have a good day.

Caparas: The international language for air traffic control is English.

Narrator: They also have special terminology so no two words will get confused.

Stearns: Runway 27 right, follow Southwest.

Caparas: The guys at Chicago O'Hare or PDK or Atlanta tower say the same things for most of our control instructions. It doesn't deviate. And that consistency is what helps us keep communications down to a minimum.

Narrator: Minimal talking is important, because every plane [pilot talking] and every controller [controller talking] share the same radio frequency. [all talking]

Caparas: And they're all on the same telephone call, 15 airplanes here in Atlanta.

Narrator: Short calls aren't the only way controllers ensure efficiency. These strips help the controllers keep track of all the planes moving through that process. Each one represents a plane. It has the flight number, the airline, the city the plane's going to or coming from, and the departure or arrival time.

Richard Jones: Once the flight plan is generated at its proposed time, as you see them right here, these will print out. This flight, Delta 1904, is an international flight. It's going from Atlanta down to Marigot. So, Delta 904, and this aircraft here is a Boeing 757-200. This airplane is scheduled to depart to 15:42 Zulu. When he departs, he's requesting to go to 37,000 feet. So this strip would then, once it's ready, they place it in one of these strip holders. So you'd find the Delta 904, which is at echo nine. They place echo nine on here and slide it to the appropriate side.

Narrator: A controller will have four or five of these strips active at once. This is how they sequence the planes in order of priority.

Stearns: The passenger doesn't see the bigger picture. The pilot thinks, "I've been sitting here. Why?" The reason why he's holding is 'cause we're trying to provide that sequence, so that we can get maximum capacity out at one time.

Narrator: Sequencing can help move planes along quicker. But how exactly does it work? Here's an example. If two planes are going the same direction, say to San Antonio and Houston, they have to be at least four miles apart, so they don't run into each other in the sky. Which means time waiting between takeoffs. But if a controller alters the sequence using those strips...

Stearns: So in this case, this is a west, a north, and a west. This aircraft's going to San Antonio, this aircraft's going to Milwaukee, and this aircraft's going to Houston. So we can depart 6,000 feet down the runway, and airborne, and roll all these.

Narrator: That Milwaukee flight can take off right behind the San Antonio flight. And now they've had three planes take off in the same amount of time.

Stearns: It makes a big difference for the ground controller to actually provide a good sequence, because it's efficient and the aircraft can keep going at the fastest rate. And that's what we do. And that's our job.

Narrator: Efficiency means fewer delays.

Caparas: If there are major delays, it disrupts air travel all throughout the country and parts of the world.

Narrator: In 2018, Atlanta Hartsfield-Jackson International Airport was ranked the best airport in the US for flight delays, with the highest percentage of on-time departures.

Caparas: 15 airplanes, we're looking at a minute behind one another, so it's not bad. 15 minutes.

Narrator: But, of course, some things are out of their control.

Caparas: You can go upstairs and you can look out of that window and you can see nothing at all, and still have movement taking place on your airport. And then there's days like today, clear and a million. That's what we call it when it's just a beautiful sunshine day and you can see forever. We can move a whole bunch of airplanes. It's 132 an hour, I believe, is our arrival rate max. On a typical day, we try to stay right around in the 120s.

Narrator: Controllers also have to contend with inclement weather. Sometimes planes can't land on their first attempt, so they'll have to pull up, circle back, and get in line to land again.

Caparas: You have to be ready to make a decision. How am I going to get this airplane back up into the air, back over to the next air traffic control facility, so that they can resequence them back into our pattern?

Narrator: Luckily, some technological advancements have made this whole process a lot easier. Remember those strips?

Jones: So, a lot of this is automated now.

Narrator: While controllers may still use the physical strips, they also show up on monitors and are automatically sent over to the next controller in the sequence. Also, technology means weather isn't as debilitating as it once was.

Caparas: There used to be a time when weather would shut your airport down.

Narrator: But now...

Caparas: Being able to forecast and project when that weather's coming, we're not surprised like we used to be.

Stearns: We go in the clouds sometimes, and that's when our equipment is all we got.

Narrator: ASDE-X, radar, and GPS positioning help controllers track a plane.

Caparas: We're able to use that technology now to actually separate and identify where those airplanes are legitimately. So we can use the term "clear for takeoff," even though we can't see the physical runway any longer.

Narrator: But all that technology doesn't mean these controllers can be any less diligent. They have to be focused and undistracted, nonstop. This is the busiest airport in the world.

Stearns: The number, the volume. I don't think many airports can handle what we do. That's the truth. All right, Delta 2452, continue. Juliet and Mike de Lima. Charlie, monitor the tower, 123.85.