As more aircraft take to the sky, new technology will allow pilots to pick their own direct routes but still avoid one another

In a windowless industrial building on the outskirts of Madrid a group of people are watching a series of colored symbols move steadily across a bank of computer screens. Each icon represents an aircraft flying over southern Europe. In an adjacent room another group are monitoring flights over part of Asia, and next door all eyes are on South America. These flights are not “live” but are simulated by Indra, a Spanish technology company, to train controllers in the operation of a new generation of air-traffic-management systems that promises to make flying more efficient by shortening flight times and reducing delays.

What is different about these virtual flights is that some are “free-routing”, which means pilots have the freedom to set their own courses instead of following one another along established flight corridors, as they presently do. Free-routing allows an aircraft to fly more directly to its destination, which for European journeys alone would knock ten minutes off average flight times, thus saving fuel and reducing carbon-dioxide emissions.

On the face of it, free-routing seems like a disaster in the making. If fast-moving jets can fly where they want the risk of collision would appear to rise. Yet the controllers in Madrid are relaxed and, apart from issuing a few course corrections to avoid a spot of bad weather, leave the aircraft to get on with it. This is made possible because the trajectory of each plane has been worked out by computers some 25 minutes in advance and the pilots have already been informed of any adjustments needed to prevent a potential conflict. Provided each aircraft sticks to its flight plan, there is no need for the controllers to intervene.

Traditionally, air-traffic controllers have played a more proactive role in keeping aircraft apart. The corridors which jets fly along function much like lanes on a motorway. They pass through sectors and each sector is monitored by air-traffic controllers with the assistance of radar. When an aircraft is about to enter a new sector, the pilot and controller communicate by radio. The controller then gives the pilot instructions to maintain a safe separation, both vertically and horizontally, from other aircraft.

It is a tried and trusted method, but one that will struggle to cope with future demand for air travel. This will be huge. In the past 40 years the number of airline passengers worldwide has grown tenfold to some 3.1 billion in 2013. By 2030 it is expected to reach over 6.4 billion.

Flight corridors frequently follow historic routes and zigzag around. Many of the routes which cross America are based on where hilltop beacons were lit to guide Charles Lindbergh’s mail flights in the 1920s. Plenty of radar systems still resemble 1940s technology and provide only a limited “view” of what is in the air. And in Europe, flights have to negotiate a labyrinth of 64 air-traffic-control areas operated by different national authorities. All this adds to journey times and puts constraints on the system because of the need to maintain the safe separation of planes.

Flying ahead

A much-needed revamp is under way. Although suffering from delays and budget constraints, America’s NextGen air-traffic-modernization program is slowly taking shape. Europe is part way through the Single European Sky initiative, which is supposed to increase co-operation between a reduced number of control centers. Japan also has a project in hand to renovate its air-traffic-control systems.

One element of this modernization involves fitting new kit to aircraft. This is a system called Automatic Dependent Surveillance-Broadcast (ADS-B). It will be compulsory for jets in Europe by 2017 and in America by 2020. ADS-B uses satellite navigation for pilots to determine their position and is generally more accurate than radar and radio-navigation aids. This allows aircraft to be safely spaced closer together, which permits more planes to be in the air at the same time. Crucially, though, it also establishes a data link to control centers and to other planes by regularly broadcasting an aircraft’s identification sign, its position and other information.

These data, when combined with the known trajectory of the aircraft, mean flight-management can now be “based on where we know the aircraft will be at any particular time,” says Gonzalo Gavin, the director of a program at Indra to install such a system at a control center in Prestwick, Scotland, run by NATS, a British company. The Prestwick centre provides en-route services across northern Britain and for flights crossing part of the busy North Atlantic. Known as iTEC (for interoperability Through European Collaboration), the trajectory-based system was developed by Indra with air-traffic providers in Spain, Germany, Britain and the Netherlands as part of the Single European Sky initiative.

In a typical flight, a pilot may climb, descend, change course at various points and speed up or slow down numerous times. But with trajectory-based management, the flight should be smoother and shorter, says Mr.  Gavin. And it is more likely to arrive on time.

The ability to predict the arrival time more accurately should mean less circling in holding patterns while planes wait to land, says Alastair Muir, operations director at Prestwick. That would allow more aircraft to use what is called a “continuous descent approach” when coming in to land. This is a procedure which involves a longer descent, more like a steady glide towards the runway. It requires less engine thrust than having to level out at various stages of the approach, so it saves fuel and is also quieter.

A wholesale switch to free-routing will not take place overnight—the aviation industry is notoriously cautious in introducing new technologies and procedures. At first pilots are likely to pick from a number of available routes before free-routing completely takes off.

It should enhance safety with an early alarm should something go wrong. Although no one knows what happened to Malaysian Airlines flight MH370, which disappeared in March, the new systems would have alerted controllers that the aircraft was not keeping to its trajectory soon after it changed course.

Being highly automated, the new generation of air-traffic-management should also help with the commercial use of civilian drones. Aviation authorities are facing increasing pressure from companies to allow drones to be used for a variety of applications, ranging from aerial photography to surveying, search and rescue, delivering goods and providing temporary Wi-Fi. Guidelines are slowly emerging, but generally the operation of civil drones remains restricted in most countries, particularly the United States.

With data-driven systems like ADS-B and trajectory management, monitoring the flight path of a drone can be automated, says Benjamin Trapnell of the University of North Dakota, which was one of the first institutions to launch graduate courses in operating drones.

Test flights by BAE Systems in Britain have also shown how a drone can be made to respond to air-traffic-control instructions. This is done by having radio communications to and from the drone relayed via a “pilot in command”, who would be a drone operator on the ground. That operator might well be in charge of more than one drone. With the cost of operating a drone only a fraction of that of a helicopter or light aircraft, the civilian use of unmanned aircraft is bound to make the sky an even busier place.

This is yet another reason why the long-awaited modernization of air-traffic control is welcome, says Andrew Charlton, head of Aviation Advocacy, a Swiss-based consultancy. But he thinks it should go much further. Organizing more airspace along functional lines rather than around national borders, as much of it now is, would greatly improve efficiency—especially in Europe. And with systems based on data, he says more competition should be possible, giving pilots a choice of air-traffic-management providers.

Nevertheless, the EU gushes about the prospects. It expects trajectory-management to enhance safety by leaving less room for human error. It hopes the Single European Sky initiative will provide the ability to handle three times as many flights, cut air-traffic-control costs and produce savings for airlines worth some €9 billion ($12 billion) a year. It also says that aircraft will on average land within one minute of their scheduled arrival time. Weary air travelers will be forgiven if they think that is a bit of pie-in-the-sky.

- Source:   http://www.economist.com