What do air traffic controllers do in a tower?
Air Traffic Control Tower
Sometimes, like many jobs, air traffic can moments of excitement, stress, and sometimes complete panic, although much of the time it's kind of boring. The stress of two planes coming together is not the type of stress I feel on a daily basis, it's another type of stress that is common with many other jobs.
Air traffic control can leave controllers feeling a prolonged, underlying stress do to the shift work and nature of the critical decisions they make on a daily basis. When you also add the fact that every word they say is recorded and can be listened to later during an incident, no matter who's at fault, the job can be certainly bring on the symptoms of stress, even if the controllers don't realize it. It can add up over time leaving people tired and on edge.
Flight Data- This position is usually the first position to work and certify on for a new person. The tasks of the flight data controller include updating weather information that is broadcast out to pilots on a recording. At Pensacola there are not weather observers out on the field, so all controllers must become limited weather observers, making corrections to the weather machine ( such as visibility, and ceiling heights) and must maintain this certification as well.
In this article I'm gonna dive into the very basics of what a tower controller actually does. I've been a tower controller in the FAA for about 10 years, giving me the the opportunity to give insights on what actually goes on behind the glass in one of the numerous control towers you've probably seen at various airports around the country.
The tower is one only one type of facility in the FAA.
The control tower is one of three different types of facilities in the FAA. There is also terminal radar approach control ( TRACON), and enroute facilities ( centers ) . Each have a specific function; the tower facility is the most associated with air traffic to the general public because it is on the airport property where the flying public can see it. The other facilities can be located several miles away from the airport property with large amounts of airspace surrounding the primary airport and the country.
I'm going to discuss the Pensacola air traffic control tower as an example of what tower controllers actually do. Pensacola tower is classified as a lower level facility by the FAA based on a complex formula of traffic volume, type of traffic, airport configuration, and various other variables. Sometimes lower level facilities can be hard because of the unstructured environment, inexperienced pilots, and mix of slow and fast traffic.
Every tower controls different types of traffic. Pensacola tower has a little bit of everything, which makes it difficult at times, despite a being a lower level. Where a big airport like Atlanta works strictly commercial traffic in a very structured way ( a massive amount) Pensacola works a mix of small military helicopters, high performing turbo prop Texan 2 aircraft, a few flight schools of small single engine aircraft ( mostly Cessna 172s ), commercial aircraft, and numerous types of general aviation aircraft from bonanzas to Leer jets.
What does a tower controller actually do?
The tower controller's responsibility is to move air traffic in a safe, orderly, and expeditious flow using specific phraseology unique to pilots and controllers. The tower controllers are responsible for the airport surface area and the designated tower airspace, generally five miles around the airport and up to 3000 feet or more, depending on the specific airspace of the tower. At Pensacola, it's four miles around the airport and up to 1700 feet above.
The airspace above and around the tower airspace generally belongs to the TRACON. The TRACON's primary job, in most cases, is to control the flow of traffic into and out of the tower airspace. Beyond the TRACON airspace lies the Enroute airspace, which is where aircraft cruise at high altitudes in between other airports and their designated TRACONs.
How tower controllers control the traffic
To become a fully certified controller in a tower, there are four positions that one must be fully certified to do. They must train on the positions with a trainer plugged in until they have met the amount of hours and demonstrated the skills necessary to work alone. At a lower level like Pensacola, it generally takes about one year of training to fully certify.
Flight data is also responsible for making sure display boards for controllers are updated with the correct information, such as runway and taxiway closures, and equipment outages. It's not the most glorious job, but it is an important function.
Clearance delivery- This position, like flight data, is not a control position, but it is the first communication with the pilot and and air traffic control. At a controlled airport, all pilots must receive a clearance to exit the tower airspace from clearance delivery. Pilots will file a flight plan that will be printed in the tower, or clearance delivery will create a flight plan for the pilot.
The clearance delivery position is responsible for issuing the flight plan on the clearance frequency over the radio to the pilot including the correct altitude to fly, the route, the TRACON frequency to contact when switched from tower, and what is known as a beacon, or squawk code. The squawk code is generated by the tower's printer and is a four digit number unique to the specific flight plan. The pilot issues the four digit code into the aircraft's transponder, the aircraft must be equipped with a transponder at Pensacola and other larger airports.
When the pilot inputs the four digit code into the aircraft's transponder it will allow the aircraft to be identified on the tower's radar display with the correct call sign ( what we call the aircraft, which is the tail number or designated company call sign) the speed, altitude, and exact location. This code is crucial to getting correct, as nothing will be displayed but a primary target, like a flock of birds, drone, or hot air balloon would be displayed.
Ground Control- Usually at large commercial airports the ground control position is the most difficult position. At Pensacola it isn't, but it can be difficult because this position is combined with flight data and clearance delivery. Here, the ground controller listens to both the ground control and clearance delivery frequencies and must manage the frequency congestion. At the same time, they must function as a flight data person. This is common at lower level facilities because split apart these position aren't normally too busy to handle, but it doesn't mean there aren't times the controller does't get very busy with all the combined duties, or one of the positions may require a high workload. And there usually isn't enough people to split them apart, and the positions would become very boring as people gain experience.
At a large tower facility these duties are usually split because they have more manning, and it wouldn't be possible for one person to handle the volume of traffic.
The ground controller is responsible for giving taxi instructions to aircraft, moving them to the primary runway to depart, and back to the gate or ramp areas from the runway. They must sequence aircraft with release windows to large airport ( given by the enroute facilities) with aircraft without times. They also must give instructions to vehicles that are driving around the airport doing inspections or maintenance work.
The ground controller is in charge of the taxiways giving authorization to enter and taxi on them. They also must must coordinate to cross any runways the tower controller is landing and departing on and report when the crossing is done. They must instruct the aircraft which runway to taxi to, which taxiways to use, and tell the aircraft how to taxi back to parking. They do this sometimes telling them which aircraft to follow, which one to give way to, and any pertinent information.
Local control ( tower controller)
Here's where the action is at Pensacola. While ground control is the beast at a larger facilities, local control is usually the most difficult, and hardest to certify on, at a lower level tower.
Local control is responsible for runway separation, and separating and sequencing traffic in the air. They must understand runway separation and apply the minimum requirement when the traffic is busy, but they also must understand the requirements in the air.
The local controller clears aircraft for take off and to land. When the aircraft is switched from the TRACON, about seven to ten miles from the airport, the local controller issues a landing clearance. When an aircraft is ready to depart, the controller issues the take off clearance and a specific heading to fly.
The local controller must be familiar with all different types of aircraft, especially at Pensacola, for a lot of reasons, but I'll give a few basic examples why. The local controller must separate arriving aircraft from their departing aircraft, departing aircraft with departing aircraft, and arriving aircraft with any aircraft they may have in the tower practice pattern that may be arriving or departing, usually doing touch and go landings ( remember those flight school Cessna aircraft I mentioned earlier) There is different runway separation criteria for different types of aircraft.
For simplicity, I'm gonna leave the airborne separation criteria out of the equation. For example, the different separation requirements between aircraft flying instrument flight rules ( IFR) and visual flight rules ( VFR). Runway separation begins and ends with the local controller.
Runway Separation
There are markers every 1000 feet down a runway with numbers on them. A they start and count down until the end of the runway. A number four indicates to the pilot that there is 4000 feet remaining. The local controller can use these, or other suitable land marks to apply what is called runway category separation. Some of examples of this are a single engine aircraft can land behind another landing single engine aircraft as long as there is 3000 feet of runway separation. A twin engine aircraft departing behind a departing single engine aircraft as long as the single engine aircraft is 4,500 feet and airborne down the runway. A Boeing 737 ( jet) departing behind a single engine aircraft means that the single engine aircraft must be 6000 feet down the runway and airborne by the time the 737 is departing.
These may not seem like large separation requirements, but it allows the local controller to anticipate and move air traffic with set limits to guide them.
Wake turbulence
Like airborne separation there are many things for the local controller to think about. Besides mixing aircraft doing practice touch and go landings with inbound and departing aircraft with different speeds and characteristics, there is a phenomenon known as wake turbulence that must be handled according to strict rules. If a large aircraft departs the full length of the runway with a small aircraft ready to depart mid field, they must wait 3 minutes from the time the large aircraft gets airborne before they can depart the small one. In some cases the controller can transfer the responsibility of wake turbulence to the pilot that is in the air, using specific phraseology.
I hope this article gives some insight into what a tower controller does. Although every airport is different, all tower controllers apply many rules with specific language everyday. Subjects such as work schedules, airborne separation, and daily life of a controller will be discussed in future articles.
Kevin
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