What can pilots do now to help reduce CO2 emissions?

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What role can pilots play in helping to make the aviation industry more sustainable and reduce emissions? The European Cockpit Association has come up with a list of operational measures and AeroTime spoke to pilot Didier Moraine to find out more.  

ECA, which represents the interest of professional pilots across Europe, said aviation needs to be put on a green path. Pre-pandemic, aviation represented less than 3% of global CO2 emissions, but the industry’s emissions are increasing. Consultancy Roland Berger has forecast that if other industries decarbonize as expected, aviation’s share of emission could rise to 24% by 2050, unless there is a significant technology shift.  

“There’s a consciousness about sustainability. It’s well understood by most of the pilot community that they have a role to play in decarbonization,” Moraine, a 737 Captain and member of the ECA environment working group, told AeroTime in an interview.  

When it comes to expected big technological changes, such as electric flying and hydrogen and more, pilots have a role to play to ensure the gains match with what was promised and to promote best practices, Moraine said. 

But ECA highlights in a position paper that there are some operational improvements that pilots, working with airports and air traffic control, can make now to reduce emissions without impacting pilots, airlines or passengers. 

“Compared to the global challenge, what we can do as pilots looks minimal but it’s very important to do it because we can have those quick wins right now,” Moraine said.  


Fuel vs Time 

The first operational measure proposed by ECA looks at balancing fuel burn against time constraints.   

“The faster we fly, the more fuel we burn,” Moraine explains. Therefore, aircraft should aim to fly at their best long-range speed, which means the most distance for the least fuel burn.   

“On European flights, you’re talking about a couple of minutes in time difference, so it’s not a lot but it could save a good amount of fuel,” Moraine said. However, this measure requires everyone to play along. If an aircraft behind is flying faster, then ATC will have to ask the aircraft in front to speed up, so it needs to be coordinated.  


The second measure involves the practice of tankering, when an operator carries more fuel than required because it is cheaper to buy fuel at certain places.  

“Everyone agrees we should ban this,” Moraine said. “If I take more fuel, I am heavier, so therefore I burn more fuel.”  

However, the ECA is keen to highlight the distinction between tankering for economic reasons and the need to sometimes carry additional fuel for safety considerations.  

“As captain, I sometimes want to take more fuel for safety reasons, for example if there are thunderstorms in the area or if there are operational constraints that might mean holding overhead. As pilots we must ensure that we retain this possibility,” Moraine tells AeroTime. 

Ground operations 

There’s a lot of measures that could also be taken on the ground, ECA highlights.  

For example, when aircraft are at stands at airports, they should always be able to connect directly to the airport’s electricity supply, which may itself come from renewable sources. That saves the aircraft having to use its APU, a small engine, to provide power and air conditioning while stationary.   

Electric tugs could also be used to pushback aircraft, rather than conventionally powered vehicles. Moraine said these are in use at some airports already, citing Oslo as an example. However, they could do more, he suggested.  

“Maybe in the future, they could take an extra step by bringing the aircraft closer to the runway, because using engines for a long taxi is very inefficient. On an aircraft like a 737, we often burn 200 kilos of fuel just on the taxi and for bigger aircraft it’s even worse.”  

Conversely, upon landing, aircraft need to leave the engines at idle to allow them to cool and shut down safely, so taxiing to the stand is therefore useful.  


Optimum slot scheduling 

The next suggestions from the ECA require the help of ATC when it comes to scheduling arrival and departure slots. 

For example, instead of keeping aircraft at their cruise speed until almost at their destination and then asking them to enter a holding pattern, it would save emissions if controllers could ask aircraft to reduce speed earlier so they arrive at a certain point at a fixed time and could then start the approach directly. Moraine said computers in the flight deck allow pilots to make calculations quite easily.  

“The idea is to avoid as much as possible the situation that you often get in London, for example, at peak time with all the aircraft in the stack and burning a lot of fuel.” 

However, with airspace still fragmented and now more and more military aircraft in the skies of Europe due to the war in Ukraine, Moraine recognizes this will be a challenge.  


When it comes to approaches, airlines can recommend a minimum flap setting, or the use of idle reverse thrust instead of full reverse thrust. These help to reduce fuel consumption and brake wear. However, with short runways or poor weather, then safety considerations come first, and crews will not use such measures, ECA highlights.  

Another way to reduce emissions is using what is known as Continuous Descent Operations. This is where the aircraft flies at its cruise speed until the optimal top of descent point. From there, the crew can put the engines to idle and then descend smoothly until the aircraft is lined up with the runway.  

“It’s the best approach because you burn almost nothing, you can save a lot of fuel,” Moraine explains. “For long-haul aircraft, we are talking about potentially saving hundreds of kilos of fuel per descent.” 

Such descents can be challenging for pilots because they require 3D thinking and some additional training. However, Moraine also recognizes that such operations are challenging for ATC, especially in busy airports with lots of traffic.  

ECA notes that the list of measures is not exhaustive and there remain many factors that have to be taken into account to ensure safe operations. 

“We are ready to contribute concretely to the collective effort to reduce aviation’s environmental footprint,” ECA Vice-President Juan Carlos Lozano declared when ECA unveiled its position paper. “Our ambition is to collaborate with the industry and regulators in promoting new operational practices and procedures bringing further environmental gains while keeping safety as a priority.” 


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