Infrastructure

We are not just considering aircraft emissions. Most environmental concerns around air travel focus on the role of aircraft, but associated infrastructure, including airports and flight paths, also have an impact on the environment, and improvements are being made.

Airports and ground facilities

Ground facilities and airports are also becoming more energy efficient in a number of ways.

• Airports are investing in offsetting schemes to become carbon neutral, most notably the ACI Airport Carbon Accreditation programme, and building 'green-certified' terminals.
• They are reducing on-airport vehicle emissions by introducing automatic metro lines, or switching to vehicles with alternative fuels and low-emission technology.
• They are providing electricity to aircraft at terminal gates using fixed electrical ground power rather than the aircraft's auxiliary power unit.
• Many airports have also installed solar and other alternative energy supplies for terminal buildings.

There is a significant impact on emissions from congestion at airports. When flights have to hold and circle before they land, or queue on taxiways before taking off, it is inconvenient to passengers and also adds to fuel use. These inefficiencies are continually assessed to determine whether operating restrictions on flights or new facilities like runways are needed.

One way that the industry is working to reduce congestion and delay (and therefore fuel use) is collaborative decision making (A-CDM), with all parties working together to make sure that aircraft engines are not started until there is a confirmed take-off time and a slot at the destination airport.

Air traffic management

The infrastructure area that makes the biggest impact on aircraft fuel efficiency is the air traffic management system. The route a plane takes, the height it flies, and the weather it flies through, all affect the amount of fuel it burns, and therefore the CO2 it emits. These factors are managed by air navigation service providers (ANSPs) who provide air traffic control services.

ANSPs are helping the industry to improve its environmental performance globally by making better use of airspace design and optimising aircraft performance. ANSPs work with regulators, aircraft manufacturers, airlines, airports, pilots and engineers to optimise ground and flight operations, improving overall aircraft performance.

In many regions of the world, mid-20th-century technology is still being used to direct air traffic. This requires aircraft to zigzag between ground-based radar posts throughout their journey, however, this is undergoing rapid change. By using new satellite-based navigational technologies and procedures known as ‘performance-based navigation’, aircraft can follow optimised, more direct routes with greater accuracy and efficiency. Cutting out unnecessary travel time saves fuel, reduces CO2 emissions and enables aircraft to use the extra airspace to accommodate increasing air traffic, reducing congestion and delays

Another procedure that is enabling aircraft to improve efficiency and reduce emissions is called ‘free route airspace’. Traditionally, aircraft have flown along fixed routes, like motorways in the sky. Free route airspace allows aircraft to plan more efficient, direct routes with stable trajectories, saving time and fuel and therefore reducing emissions. This procedure requires cooperation among the countries which an aircraft flies over, and is being applied successfully in Europe.

The engagement and cooperation of governments and international institutions is critical if the potential of new navigational technology is to be realised. Airspace is governed by sovereign states, meaning that any reform needs governmental buy-in. But aviation transcends national boundaries, therefore airspace should be organised and air navigation services delivered in line with operational requirements, rather than national borders. This would mean that airspace would be controlled across multiple countries.

The greater harmonisation of airspace allows aircraft to navigate seamlessly across national borders on the most efficient routes. In some regions, such as the Middle East, large areas of airspace are reserved for the military, meaning civil aircraft must fly around these areas, adding time, fuel burn and emissions.

The Civil Air Navigation Services Organisation (CANSO) is working with governments in those regions to free up this airspace when not required for military purposes to allow for more direct commercial routes.

In Europe, a collaborative project is underway called the Single European Sky ATM Research (SESAR). It is part of the vision to transform Europe’s aviation infrastructure, enabling it to handle future growth while minimising environmental impact with efficient flight routes and optimised trajectories.

Once in place, the Single European Sky will be a key enabler for enhancing sustainability, contributing to an effective environmental improvement of the sector and helping to be more resilient. 

The SESAR programme was initially launched in 2008 and the third phase runs until 2031. SESAR aims to contribute to CO2 reduction by reducing fuel burn by between 250-500 kilograms per flight between 2012 and 2035, a relative improvement of 5-10% – this corresponds to between 800-1,600 kilograms of CO2 emissions per flight. 

The second phase of the programme delivered 127 solutions that could be deployed in the system to reduce emissions from air transport – in total, an estimated 4% reduction in CO2 emissions per flight could be achieved with the solutions delivered so far.

A similar modernisation of airspace is underway in the United States. Once fully implemented, the Next Generation Air Transportation System (NextGen), like SESAR, will result in significant emissions reductions. 

The NextGen project is being undertaken by the US Federal Aviation Administration (FAA) and aims to simplify US ATM by rolling out Performance Based Navigation (PBN), an advanced satellite-enabled form of air navigation, and other satellite-based technologies known as Automatic Dependent Surveillance-Broadcast (ADS-B) that replace radar technology, as well as collaborative air traffic management technologies.

Reacting to changing weather conditions is another way flights can become more efficient. In the US, a new NASA weather software programme is helping US airlines improve efficiency by allowing flexible routing. It allows pilots to react to changing weather conditions and alter their routes accordingly, rather than simply following a predetermined flight path.