This is Heathrow Airport—Britain’s Busiest. Each day, about 650 flights take off from one of its two runways. At the busiest times, this represents one aircraft every 45 seconds. Of those 650, about twenty flights daily head to Frankfurt. Between British Airways and Lufthansa, flights on this route depart more than hourly throughout the daytime. This makes Frankfurt one of Heathrow’s most frequently served destinations. Despite the unremarkable nature of such a flight, the complexity of even this one hour hop is enormous. It takes dozens of people spread out all across the continent to coordinate and navigate just one of these flights safely to its destination.
This is everything that happens within the 90 minutes it takes to for a plane to get from its gate at Heathrow to its gate in Frankfurt. Hours before the flight is scheduled to take off, British Airways will have sent a flight plan to here—Eurocontrol’s Network Manager Operations Centre in Brussels. Now, Eurocontrol is an intergovernmental air traffic management organization. “Prissinotti: [00:01:57] Well, Eurocontrol is an intergovernmental organization of 43 states in Europe and beyond and we do air traffic management service transversal.” What that means is that Eurocontrol deals with a variety of different aspects of the job of managing air traffic in Europe.
One element of that is what’s called network management. This function essentially involves, from this room, making sure that flights make their way through Europe as safely and smoothly as possible. That field is headed up by Lacopo Prissinotti—Eurocontrol’s Director of Network Management. “Prissinotti: [00:05:53] So here you see that's our operational room. The scope is to provide services to 43 air navigation service providers, to provide services to more than 500 airports, and to provide services to more than 1000 airlines over the network.” One corner of this room is devoted to checking those flight plans that airlines send in. Now, what they need to check is that these plans are following the rules.
You see, to aircraft, the sky does not look like this, but rather this. At least in most of Europe, there are thousands upon thousands of pre-defined airways each with their own rules on directionality and routes and more so aircraft not only need to fly on these roads but they also need to follow the rules of the roads. Looking at this map, you can see why, for example, you won’t see many planes flying over this area in the east of England—there just aren’t many airways there.
Eurocontrol sends the fight plans through a program to check that they follows these rules but if the computer rejects it, then it goes to these people in about 2% of cases who coordinate with the airline to fix it manually. From there, they’ll distribute the flight plans to all the air traffic control centers that each aircraft is expected to fly over. That process happens before the flight has even taken off.
Going back to that British Airways, Heathrow to Frankfurt flight, once their plan is approved, the plane is fueled, loaded, and ready to go, the pilot will get approval from British Airways’ flight dispatcher and Heathrow’s ground control to push back. Ground control at Heathrow is responsible for navigating all the vehicles and planes safely across the apron up until when they reach the runway. The moment an aircraft gets to the runway, they are then the responsibility of tower control which, assuming all is well, clears them for takeoff.
As the plane reaches altitude, it will be passed off to the London Terminal Control Centre located near Southampton which navigates aircraft through the complex London-area airspace until they reach 24,500 feet, or flight level 245, which for this flight should be just about when it reaches the coast. From there, they’ll be transferred to the London Area Control Centre, which is physically located in the same building, to navigate them across the channel. Once they reach about halfway across, however, they leave the UK’s airspace and enter Belgium’s.
With that, they are now the responsibility of the Maastricht Upper Area Control Center—also managed by Eurocontrol. “Santurbano: [00:00:20] We are a European nonprofit. A cross-border military civil air navigation service provider. And, uh, yeah, our job is that we handle safely and in an efficient and performed way all traffic above flight level 245—24,500 feet.” To reiterate, they handle traffic across this whole area, above 24,500 feet or 7,500 meters. “Santurbano: [00:01:45] So we manage, what, more or less 1.9 Million of movements per year, so between 5,000 and 5,700 movements depending on the on the season and the day, per day.
” It’s one of the busiest and most complex airspaces in Europe especially as it receives a significant amount of traffic climbing from or descending into four of of Europe’s five busiest airports—Heathrow, Schiphol, Frankfurt, and Paris Charles de Gaulle.
Every single one of those flights, as long as it’s between flight level 245 and 660, is in contact with the people in this room. Now, the Maastricht control centre’s airspace is divided into three sector groups—the Brussels, Hannover, and DECO sector groups. Each sector group is staffed by their own set of controllers who only work on their group—a Brussels sector group controller would very rarely switch over to the Hannover group, for example. Many controllers spend their entire careers working at one control center within one sector group. This allows them to really learn the design of their airspace in depth. Each of the sector groups is then divided into sectors themselves. Now, sectors can be divided both horizontally and vertically. For example, there’s the Luxembourg sector, between flight level 245 and 355, and also the Luxembourg High sector, above flight level 335.
At the very busiest times, each sector will have its own dedicated set of controllers. At less busy times, though, they can and do combine the upper and lower sector together so they’re staffed by one set of controllers. At the least busy times, such as in the middle of the night, they’ll often combine a number of sectors. For example, the entirety of Belgian airspace is typically controlled by one set of controllers in the dead of night. In charge of each sector are two controllers working as a team. One is in charge of talking to pilots, the other is in charge of talking to their counterparts at other sectors to coordinate handovers. Now, in practice, for that London to Frankfurt flight, before it enters Maastricht’s airspace in the Koksy sector, they’ll receive info on where and at which flight level it will arrive.
They’ll also get info from the flight plan on where it’s supposed to exit their sector. An aircraft also might enter at one altitude and be planned to exit at another. The task is then to safely navigate the aircraft from the entry point to exit point and deliver it to the next sector at the desired altitude. Now, assuming no added obstructions such as weather or airspace closures, the main obstacles planes need to avoid at this altitude are other planes. There are rules about how close a plane can be to another in order to avoid any chance of midair collision and the controller’s job is to make sure that these rules are not broken or, if they are, to get to the correct level of separation as soon as possible.
An aircraft must be either vertically or horizontally separated from all others at any given time. What this means is that typically, a commercial aircraft cruising at this altitude can be as little as 1000 vertical feet or 300 vertical meters away from another. That’s vertical separation. Alternatively, an aircraft can be horizontally separated. They have to be at least 5 nautical miles, 6 miles, or 9 kilometers apart if they’re within 1000 feet vertically. Now, in order to achieve the goals of getting the aircraft to its exit point without breaking minimum separation, there are three factors the controller can instruct the pilot to change—speed, altitude, and direction.
That is essentially what a controller spends most of their time doing—determining where the aircraft needs to go, how to get it there, and communicating that to the pilot. Soon enough, after just a few minutes, as the aircraft reaches its exit point from the sector, it will be passed onto the controller of the next sector. In this case, it’ll go into Nicky Sector, then Olno sector, then it will move onto airspace beyond what the Maastricht Upper Area Control Centre manages. As the plane starts to descends it will be passed onto the controllers dealing with lower airspace, then approach and tower control to guide it into landing. All told, on just this hour long flight, more than a dozen air traffic controllers will have dealt with this aircraft. But that’s what happens when absolutely everything is going right, which is rarely the case. You see, back at Eurocontrol’s network manager room, the second thing they do with the flight plans they receive is make sure that once an aircraft gets flying, there are actually enough air traffic controllers to manage it.
“Thomas: [00:01:50] So, air traffic control, they decide on their capacity i.e. how many flights can safely be handled in one piece of airspace by one air traffic controller. That's their decision based on their staffing, based on their infrastructure, their tools, and that is communicated to us.” So, there’s a limited number of flights a single air traffic controller can handle, but there’s also a limited number of air traffic controllers. It’s no secret that Europe, along with much of the world, is suffering through an air traffic controller shortage right now. Simultaneously, also along with much of the world, Europe has been experiencing a tremendous increase in its number of flights.
This supply and demand mismatch has consequences. In 2018, 60% of all en-route delays—as in, while the aircraft is actually flying—were because of not having enough air traffic control capacity. Part of Eurocontrol’s job, therefore, is to utilize the limited resource in the most effective way possible. Often, they reduce overall delays by delaying flights. Sometimes its just for a few minutes, sometimes it’s for longer, but if you’re flying in Europe and you hear that your flight is delayed for air traffic control reasons, that decision was probably made in this room. It’s just like a ramp meter on a highway—they let a manageable number of flights fly at any given time when there are capacity constraints. Now, when a flight receives a delay by Eurocontrol, the airline essentially has two choices—accept the delay and wait it out or fly a different route.
Airlines have access to Eurocontrol’s system to help them make this decision.“Thomas: [00:09:26] For instance here is a flight, it's a Thomas Cook flight from Manchester going to Antalya in Turkey and they have planned this blue route here.” This is the route that Thomas Cook has decided is best for them—it’s the least expensive considering fuel costs, overflight costs, and everything. Given that it flies through capacity constrained areas, though, to fly this route, they would have to sit through a delay. “Thomas: [00:10:05] Through our system now they can look at to see OK where our routes that do not give them delay. Those are all the blue routes you can see here and actually then there is a gray route here which is the shortest of the blue.
A system says if you want to avoid your route which is delay you can take Blue routes or the shortest blue which is the grey and it's up to you.” The airline can then go and decide whether it’s worth it to them to fly the alternate route or wait out the delay. Eurocontrol’s network management role really is most applicable on the worst days for flying in Europe. Their job is to make the bad days as ok as possible. An example of a really bad day for flying was Thursday, May 9, 2019. The main issue was a large-scale French air traffic controller strike meaning there was very little air traffic control capacity in French airspace—one of the busiest areas. “Celik: [00:03:56] If you look at this map, that shows the magnitude of the impact on the sectors.
The color red means that there were delays in the order of 45 minutes or above per flight.” On days such as this, many airlines will choose to fly around France as to be less delayed but, of course, the ATC centers in the surrounding countries need to be able to cope with demand. “Celik: [00:04:30] Starting from three to four days before this event is confirmed we would coordinate with Spain, North African countries, Algeria, Tunisia, we would coordinate with Switzerland, Italy, Germany, Karlsruhe, we would coordinate with Maastricht and UK to be able to get extra capacity for all those who has to go out. So one alternative route from UK to go down to south of Spain and continuation on that what we called Tango route.” Tango route takes planes way out west into oceanic airspace to take a wide curve around French airspace and is commonly flown when French airspace is restricted.
It is, of course, not efficient. A flight from Alicante to London, for example, which normally takes just two hours, would take over three by using Tango route but overall, it would typically arrive earlier than if they waited for approval to fly through French airspace.
What made the 9th of May even worse is that drones were spotted at Frankfurt airport meaning all arrivals and departures were stopped. “Celik: [00:14:02] What we do we immediately get in contact with all the airports around if you like. You know this was the case in Frankfurt.
We contacted Amsterdam, Munich, Paris, Brussels immediately to try to understand incoming flights, so live traffic, where they could land.” Eurocontrol will get information from the surrounding airports on how many diverted aircraft they can handle and passes this information onto airlines so they can quickly book a diversion slot for their aircraft.
All told, there were over 300,000 minutes of delays on May 9th, but initial calculations determined that there was the potential for over 1 million minutes of delays which means that Eurocontrol likely succeeded in their task of improving the day. Eurocontrol’s network manager room is expected to be quite busy in the coming months. Right now, in early June, they already know summer 2019 is going to be messy. It’s the busiest period of the year for flights and there’s actually less air traffic control capacity than there was in summer 2018 when they had 26 million minutes of delays.
They fear this summer could be worse but, they made their action plan months ago, and will be here nonstop through the coming months to make the summer travel season as smooth as it can be. Overall, this room, air traffic control centers, and the rest of the world’s air traffic management infrastructure are crucial tools to make sure that routine, uneventful flights like London to Frankfurt stay uneventful. One thing that aviation loves is checklists. They make sure you complete crucial steps and that’s why, when I launch something new, I have my own checklist of crucial steps.
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