Background information
Through the park with the insect battle tank: I played "Grounded 2"
by Debora Pape
Is there a signalman in the control tower?
30.8.2019
Translation: machine translated
Pictures: Thomas Kunz
To ensure the safety of traffic in the surrounding airspace, air traffic controllers use high-tech navigation, radio and radar systems. But human communication and control are even more important than all these instruments.
According to Vladi, the air traffic controller's main task is very simple, "to prevent collision on the ground and in the air, that's all."Air traffic controllers use a wide variety of technologies to control the complex flow of flights. So they don't do the same thing all day long. Each of the four or five air traffic controllers in the tower has a different job.
Assigning transponder codes for radar
Christoph, seated on the far left, is in charge of ground clearances, the famous "clearance deliveries", i.e. aircraft still at the gate. Once the aircraft doors have been closed by the cabin crew and the plane is ready for take-off, Christoph calls the flight deck by radio to inform them of the weather and the latest details about the flight itinerary.
Thanks to the transponder code, air traffic controllers can read the flight number, altitude and speed of the aircraft. There are also specific transponder codes. If an aircraft is in an emergency situation, the pilot must change the code. For hijacked aircraft, for example, "Squawk" is 7500.
Coordination: priority to military aircraft and Rega
As well as coordinating with Dübendorf, Xandel, in its role as Ground Control, is also responsible for lighting the runways, the beaconing as it is known in the jargon. Control of the light beacons - switching on, off, individual selection - is carried out from the control tower.
Stop bars - the most important red beacons - are located at the intersection of each take-off or landing runway. For pilots, it's like a red light. They can only cross the runway after receiving the green light from the air traffic controller.
Runway lighting has to be adapted to suit the conditions: night, snow, rain and fog. I ask Xandel what method he uses to light the beacons. "Generally, I just have to look out of the window."
Switchmen keen on action
Like all air traffic controllers at Zurich Airport, Xandel works not only in the airport tower, but also at the area control centre in Dübendorf, also known as the Area Control Centre (ACC), in charge of approach control. In these roles, they direct arrivals and departures to and from Zurich airport.
"Cleared to land" - "Autorisé atterrissage piste..."
Sitting next to Xandel, Stefan, airfield controller, hasn't taken his helmet off since I arrived in the tower. He coordinates aircraft for take-off and landing and gives pilots permission to take off, land and cross runways.
Then he addresses the pilot again: "Contact departure", which means for the pilot that he must now change the radio frequency. The frequency is recorded in the aircraft's flight management system, but the change of frequency is done manually by the pilot. This then passes to the controllers in Dübendorf. The control tower at Zurich airport is only responsible for the very first phase of an aircraft's take-off.
For landing, the situation is intended to be different. When an aircraft arrives within 20 kilometres of the airport, it must contact the tower. For the approach procedure, it lines up in an air corridor and then receives landing clearance from Stefan. "Clear to land, runway one four," Stefan says over the radio, meaning that the plane can now land on runway 14.
"A few years ago, a plane veered off the runway," explains Vladi. "Because of the height of the trees, the signalmen only noticed it when they saw people going along the runway. Hence the presence of this camera."
But Stefan doesn't just direct the planes by looking out the window at the runway. Ground radar information for all runways and approaches is displayed on one of his four screens. Like the planes, all the cars and buses travelling around the airport are fitted with transponders. All the vehicles in the airport appear on Stefan's radar screen. An installation located in Dock E generates a radar image.
Another of Stefan's screens shows the airport's cross-track configuration. As take-off and landing are always into the wind, wind direction and strength are displayed on this screen. On the next monitor, Stefan sees the current flight plan. All departing flights are displayed on the left half of the screen, all approaching flights on the right half.
Despite the three different radar systems and numerous displays, the most important one, i.e. take-off and landing clearance, is controlled by the air traffic controllers and broadcast exclusively by radio on the VHF bands.
There are now high-tech systems that allow air traffic controllers to enter instructions for the pilot in the cockpit in text form. Only installed on the most recent aircraft, this system is called CPDLC (Controller-Pilot Data Link Communications), a technology that won't catch on in the tower, switchers explain to me, because transmission times there are simply still too long.
The system is called CPDLC, which stands for Controller-Pilot Data Link Communications.
Locating drones with binoculars
On the radar, Stefan can identify all the aircraft flying over Swiss airspace by zooming out. As everything is visible on the radar, I'm surprised that there's a pair of binoculars at each station. Vladi explains to me that they need them when a drone gets lost in the air around the airport or to locate objects to be removed from the runways.
Communication at the centre of everything
Air traffic controllers work with radar systems that are both old and state-of-the-art. That said, the most important part of their job is communication and self-control. They are fully responsible for flight safety. I'm surprised to see that they are still so dependent on radar and binoculars, and that tools like CPDLC have not yet made their mark. After all, isn't it said that the best is the enemy of the good?
As flight operations at Zurich airport come in waves, traffic is increasing again. As far as I'm concerned, it's time to leave the control tower and let the air traffic controllers get on with their work.
As air traffic operations at Zurich airport continue in waves, traffic is increasing once again.
Testing devices and gadgets is my thing. Some experiments lead to interesting insights, others to demolished phones. I’m hooked on series and can’t imagine life without Netflix. In summer, you’ll find me soaking up the sun by the lake or at a music festival.
Background information
Interesting facts about products, behind-the-scenes looks at manufacturers and deep-dives on interesting people.
Show all
