Clean machines Part II

While engineers can do much to improve the environmental profile of individual aircraft, these efforts could be undermined by inefficiencies in the world’s air traffic management (ATM) systems, which are creaking under the strain of the industry’s continued growth.

To give some idea of the scale of this problem, the UN’s Intergovernmental Panel on Climate Change(IPCC) estimates that a worldwide 12 per cent inefficiency in ATM is directly responsible for 73 million tonnes of CO₂emissions and nearly $13.5bn (£6.75bn) in unnecessary fuel costs.

A recent US government report claimed that delayed domestic flights in 2007 cost $1.6bn in wasted fuel and led to the emission of about 7.1 million metric tonnes of carbon dioxide. And if you think that sounds bad, the statistics here in Europe — where we have the added burden of national borders — are even more disturbing.

According to Giovanni Bisignani, director general of the International Air Transport Association, European ATM costs are 30 per cent higher than in the US, and inefficiency costs airlines an additional €3.3bn each year and emits 12 million tonnes of CO₂ annually.

Fortunately, around the world, scientists and engineers are working on the unified, streamlined systems that will be required to untangle this mess.

In the US the Air Transport Association is pushing for the modernisation of air traffic management systems through its Smart Skies campaign, while in Europe researchers working on the single European Sky initiative hope to cut across international differences with a suite of communications and computing systems that will create a unified European air traffic management system.

Imperial College air traffic control specialist Dr Victoria Williams, who is closely involved with this initiative, said one of the most pressing issues is to enable aircraft to fly more direct routes.

‘The current routes use ground-based navigation systems which means you don’t fly in a straight line but follow these ground-based radar beacons and therefore tend to fly longer than is necessary. This adds up to an inherent increase in the fuel burn.’

Another pressing issue is finding a better way of dealing with restricted military airspace. ‘we have a lot of military airspace that aircraft have to fly around — so one thing is to improve shared-use of airspace so that it can be switched over to civilian use at high density traffic times,’ said Williams.

One of her own areas of research concerns the use of ATM to subtly alter cruise altitudes to prevent the formation of persistent con-trails, which turn into Cirrus clouds and are thought to contribute to atmospheric warming.

Another idea that is gaining momentum is the notion of decentralising control; moving it away from the rigid centralised air traffic control systems, and equipping aircraft with some of their own decision making capabilities.

One project is Argus, a collaborative effort between, among others, Southampton University, BAE Systems and Qinetiq, which is looking at developing advanced computing techniques that could enable aircraft to do just this.

BAE’s David Nicholson said that giving aircraft some decision-making capabilities of their own will enable air operators to make far more efficient use of the airspace. Such systems could, for instance, help reduce the problem of ‘stacking’ where queues of planes circle round and round waiting for a landing slot. ‘Nicholson said that landing slots are currently assigned centrally and there is a big burden on central decisions making. ‘Argus distributes this decision-making process and allows aircraft to negotiate amongst themselves over landing slots and reach a more timely decision.’

While BAE is now mainly interested in applying this technology to control and manage UAV flight paths, Nicholson agrees that more intelligent aircraft look likely to an important component of future air traffic control systems. ‘The concept of decentralisation makes a lot of sense. When we used computer simulations to compare it with centralised solutions we found that we could deconflict routes, put more aircraft into the sky and have more efficient outcomes.’

Though the challenges are steep, the technical solutions to the world’s current air traffic management woes do appear to exist. Perhaps the biggest hurdle will be stoking up the political will required to impose systems that are likely to come into direct conflict with staunchly-held notions of national sovereignty.