Better Air Traffic Management: A Flight of Fancy?

The average commercial flight in Europe flies 49 km out of its way because of air traffic management (ATM) requirements, meaning a lot of time wasted, fuel squandered, and unnecessary emissions. The extra distance flown is usually the result of congestion. With 30,000 flights a day on average, the skies over Europe are busy—and getting busier. But the problem is compounded by a creaking, inefficient ATM system that is little changed since the 1960s. It is still largely reliant on terrestrial very high frequency (VHF) communications, for example, and is highly fragmented—while the US has one air navigation service provider (ANSP), Europe has 37. A flight from London to Athens may involve 10 ANSPs in 10 different countries, with each needing to approve flight paths, manage flights, and complete handovers. The upshot is an ATM system that is half as efficient as its US counterpart.

The European Union (EU), home to more than two thirds of Europe’s ANSPs, has long known there’s a problem. In 2004, it launched its Single European Sky (SES) initiative to consolidate ATM across the bloc and there­by cut flight times and emissions. However, the project has been stuck in the departure lounge ever since. Political wrangling, sovereignty concerns, and trade union opposition have all but ruled out ANSP consolidation, while many observers warn that the concept of centralization is flawed, not least because of the risk of system-wide outages. “Although some gains could be achieved by merging several ANSPs, it looks like a political ‘mission impossible,’ and even undesirable,” says Wouter Dewulf, professor of air transport management at the University of Antwerp in Belgium.

Instead, the EU’s focus has shifted to improving ATM performance—and emissions reduction—through digitalization, technology, and efficiency gains. To support this work, it has established an R&D arm of SES, the success of which could yet innovate the initiative out of deadlock.

The Single European Sky ATM Research 3 Joint Undertaking—SESAR for short—develops and deploys technologies to modernize air traffic management. Its scope includes conventional aircraft, drones, air taxis, and high-­altitude vehicles, and is based on an ATM Master Plan and Digital European Sky blueprint. So far, so bureaucratic. But in practice, SESAR coordinates and funds a huge number of projects at the cutting-edge of aviation, with around €2.7 billion (US $2.9 billion) invested since 2015. Its current projects alone are expected to save 112 million minutes of flight time, 1.1 million tonnes of fuel, and 3.5 million tonnes of CO₂ emissions by 2030, not to mention €5.6 billion (USD $6 billion) in costs.

The range of projects is huge. A highly productive area is the development of remote towers, where traffic in and out of one or more smaller airports is managed from an off-site location rather than an on-site air traffic control tower. In 2021, for instance, London City Airport became the first major international airport to be controlled remotely, with a 50-meter digital control tower at the airport beaming enhanced reality images to an air traffic control center 115 kilometers away. SESAR supported much of the research behind the technology.

Similarly, with an eye to the main goal of a single European airspace, SESAR is supporting so-called virtual centers. In these, the provision of ATM data services, such as flight data and radar and weather information, is centralized, red­ucing the workload of air traffic controllers and increasing flexibility and stan­dar­dization. For example, Avinor, the Norwegian ANSP, announced in May 2023 that it will introduce a virtual voice communication tool in several of its control centers. The technology, which will free up voice frequencies, builds on SESAR research. SESAR’s other “smart ATM” projects include using AI to automate routine ATM tasks performed by controllers, opening up high-altitude airspace, and developing U-space, a frame­work for drone use.

But it is the lateral thinking and highly ambitious projects that are the most eye-catching. The fello’fly concept is one of them. Developed by European aircraft manufacturer Airbus, the system is based on the energy-efficient V-shaped flying formations used by geese, so-called wake-energy retrieval. At its simplest, an aircraft trails about 3 kilometers behind—and 350 meters below—a wing of another similarly sized aircraft. The positioning allows the trailing aircraft to “surf” on the updraft generated by the leading aircraft’s vortices, the swirling tunnels of air formed by wing tips, reducing its thrust requirements. The concept has obvious advantages for fuel consumption and emissions reduction; Airbus’s own trials have dem­on­strated fuel savings of 5–10 percent. But there is also significant potential for improved ATM.

Under Airbus’s proposals, two aircraft would take off from the same or different airports and rendezvous at a designated air traffic control waypoint. The trailing aircraft would then maneuver into position. At this point, the pair become a single unit for ATM purposes, with the lead aircraft conducting all communications. A good example might be a flight from Rome to New York rendezvousing with a flight from Istanbul to Toronto at a waypoint over Germany, and then flying in formation until the aircraft begin their descent. In theory, the formation could be joined by other transatlantic flights at waypoints across Europe or the Atlantic. The ATM workload reduction possibilities are therefore considerable, even if only pairs are formed. “Imagine the potential if fello’fly was deployed across the industry!” said Sabine Klauke, Airbus’s chief technology officer.

Airbus admits, however, that the concept, already successfully tested during a special paired flight between Toulouse and Montreal, is not without challenges. Such close proximity flying is at the limit of ATM regulations, and only deemed safe if certain conditions are met. These include extra pilot training and aircraft adaptations to ensure safe maneuvering and formation flying. There are also commercial considerations around which aircraft will lead and which will trail. In addition, a lot of work will need to be done on ATM protocols and regulations to ensure air traffic controllers don’t end up doing more work to manage formations than for individual flights. But this is the case for many of the more ambitious SESAR projects and has not stopped Airbus pressing ahead with plans to introduce fello’fly into commercial service later this decade.

A very different but equally innovative concept is the SESAR-backed ECHOES project, which aims to provide space-based ATM. Communication, navigation, and surveillance (CNS) services are the bedrock of air traffic control. CNS is traditionally conducted using ground-based infrastructure such as radar and VHF communications (voice and data), both of which are used for most flights today. But as neither can “reach” beyond a few hundred miles, there are huge gaps in oceanic and remote-area CNS coverage. High frequency (HF), as opposed to VHF, radio, and designated flight paths, such as the North Atlantic Tracks, help to maintain communications and safety in these areas. And in recent years, global navigation satellite systems have enabled aviation surveillance technologies, such as ADS-B (automatic dependent surveillance-broadcast), to offer positioning data. But the problem is that none of these alternatives provide full CNS services, and some suffer from significant data transfer delays, or latency. For safety reasons, aircraft must therefore fly further apart—increase their separation minima—when there is no full CNS coverage. The result is higher costs for airlines, increased emissions, and more headaches for air traffic controllers.

The ECHOES project, run by the startup Startical, aims to tackle these problems by testing the deployment of VHF infrastructure in space. Systems like ADS-B rely on satellites that are around 20,000 kilometers from Earth, thereby limiting their usefulness for communications because of latency. But by launching satellites into low-Earth orbit (just a few hundred miles above Earth), Startical hopes to provide full VHF voice and data communications with no latency anywhere in the world. The benefits are clear. “We expect to see safety levels improve as well as increased operational efficiency and a reduction in the environmental footprint of aviation all over the world,” said Startical’s Jose Alberto Gonzalez Pita in an interview with SESAR. In addition, existing aircraft will be able to use the technology straight away as they already support VHF services. However, the technology will not be fully functional until an entire constellation of satellites can be placed in orbit, an expensive undertaking, and regulatory changes will also be required. Startical is planning to have everything in place by 2030.

With many other SESAR projects expected to bear fruit this decade, it looks like innovation could yet rescue the troubled SES policy.

David Reay, Contributing Writer
Sønderborg, Denmark
[email protected]

Disclosure Statement

No potential conflict of interest was reported by the author(s).