Efficiencies gained through improvements to operational practices can make a big difference. At every step of a plane’s operations there are actions that can reduce its fuel burn and consequently its emissions.
Airlines are saving fuel through more efficient procedures and weight reduction measures. These can range from ensuring the plane’s engines are clean to developing and using new arrivals procedures. Some airlines taxi to the runway on one engine instead of using two.
On the ground
When parked at airport gates, aircraft must be powered to provide air conditioning, electricity on board and also to start the engines before it departs. Aircraft are equipped with a small generator in the tail called an auxiliary power unit (APU). A large number of airports are now equipping their gates with fixed electrical ground power and pre-conditioned air, allowing pilots to switch off the APU and save fuel and noise whilst on the ground,
Airports are also working to power ground service equipment (baggage loading devices, catering trucks, passenger buses) with more efficient sources of energy, such as natural gas or electricity.
As aircraft taxi from the gate to the runway, there are techniques either in operation, such as single-engine taxiing, or in development, such as self-driving devices, which allow aircraft to reach the runway without using the full power of the engines.
Airports, airlines and air navigation service providers are also working together on so-called ‘green departures’ through which aircraft can take off and climb at a steady rate to reach the most efficient phase of flight – the cruise – faster.
Despite the size of an aircraft, they still burn less fuel when they have less weight on board. So airlines are finding ways of reducing the weight of a huge number of items carried – everything from food service trolleys, to seats and carpets, to loading just the right amount of water for each flight, rather than filling the tanks each time. These can result in some significant savings.
Airlines and air traffic controllers are also working together to take advantage of weather conditions at high altitudes. In a series of projects, pilots and flight planners have been studying wind patterns just before the departure and routing the aircraft along strong wind streams. Despite sometimes flying a much further distance, these flights have both reduced flight time and emissions. Flexible routing is taking place particularly on long routes in uncrowded airspace, but new surveillance technology much like GPS systems will allow it to be deployed on more crowded routes.
Traditionally, flights have descended from cruising altitude to land at airports in several steps, descending from one altitude to the next then ‘levelling out’ by powering up the engines. New technology allows much more accurate surveillance of where each aircraft is located in the airspace and therefore a more comprehensive picture of the traffic environment. This has led to a new technique – continuous descent operations – which allow aircraft to almost ‘glide’ into the airport, with engines at a very low setting. This can not only save fuel, but reduce noise impact on communities around airports. It is being used at more and more airports around the world, depending on weather and traffic conditions.
There are also more carefully tailored techniques being developed which take advantage of sophisticated navigation technologies to determine the most appropriate tightly controlled flightpaths into airports, specifically with difficult runway approaches – either if they are in mountainous areas or as a way to avoid flying over communities. These approach techniques can save millions of tonnes of fuel and CO2, as well as reducing the number of people impacted by aircraft noise around airports.