What would a perfectly fuel efficient flight look like?
Carbon emissions caused by fuel burn form an airline’s biggest environmental impact. That’s why one of the most important ways to decrease the environmental impact of aviation is to improve fuel efficiency. Finnair has been investing in this for years.
"During every flight, we make several decisions that impact fuel consumption. Even decisions that might appear small have a large impact when they’re repeated on thousands of flights every year” says Tom Hakala, who’s the technical lead responsible for the fuel efficiency of Finnair’s flight operations.
On 17 February at 1pm Finnair will, in cooperation with Fintraffic ANS, fly from Helsinki to Kittilä to test how much fuel consumption can be decreased when we strive to optimise all parts of the flight for fuel efficiency.
Fuel efficiency will be considered, for example, by choosing a fuel efficient route, optimising the load and weight of the aircraft and minimising queuing and unnecessary stops during taxiing, as well as using the airspace efficiently.
The flight will utilise biofuel bought by Finnair’s customers through the Push for Change program since 2019. The biofuel won’t be used at Helsinki airport, as Finnair’s biofuel is manufactured in California and it wouldn’t be sustainable to transport it to Finland. Instead, San Francisco airport will receive biofuel equalling 50% of the fuel consumption of Finnair’s HEL-KTT flight. According to the industry standard practice, Finnair can claim the resulting emissions decrease.
Best result through collaboration
The best fuel efficiency is achieved through tight collaboration by the teams working at air traffic control, the airport and airline.
“It’s crucial that the organisations actively share data with each other. When all parties know the same things, we can make decisions that lead to bigger emissions decrease than if everyone just optimised their own area”, says Finnair’s VP of Sustainability, Anne Larilahti.
“The pandemic is an opportunity. When there’s less traffic, it’s easier to do things as planned.”
Fuel efficiency is optimised at the following stages of the flight.
Before the flight
Finnair’s routes are as fuel efficient as possible. We usually aim to fly to the destination the shortest possible route, considering the weather. Turning away from the route for a few minutes can burn hundreds of kilos more fuel. Having said that, the most direct route isn’t always the most energy efficient. Sometimes the wind is against you, and you can achieve better fuel efficiency by flying a slightly longer route.
Finnair’s Pilot Briefing Fuel Dashboard is a flight preparation tool used by our pilots. It produces data to support the pilots’ fueling decisions. The captain makes fueling decisions based on the flight plan and their own consideration. There’s always enough fuel, and some disruptions like landing on another airport or a go-around are considered.
The lighter the plane, the less fuel it burns. Catering and water are optimised according to passenger numbers. The centre of gravity of the aircraft should be as far back as possible, considering restrictions, to minimise the aerodynamic drag and thus increase fuel efficiency.
Pilots determine the need for de-icing visually before departure. If the weather conditions require anti-icing, Finnair pilots take advantage of the SureApp application to consider which level of anti-icing provides appropriate weather protection for takeoff. Precise decisions enable a decrease in de-icing treatment time, burned fuel (as the engines are running for that time) and environmental effects.
The aircraft will usually taxi out for departure and in after landing with one engine in Helsinki. The CDM production control system at Helsinki airport gives departing planes their own time window, so they don’t need to queue or make unnecessary stops. Taxiing with one engine at departure will save on average 100kg of fuel in the A350 aircraft.
Accurate departure is important. Passengers can have an impact on this by being on time for their flight. Sometimes we need to wait for transfer customers from other flights, and the delay of one arriving flight can impact several departures. This can increase fuel burn: catching up the lost minutes by flying faster is expensive. Catching up every minute lost on the ground burns on average 100kg of fuel.
Pilots can optimise fuel burn by adjusting altitude and speed. The Finnair A350 aircraft are equipped with a program that calculates an optimal flight profile for fuel efficiency based on speed and altitude.
Wind impacts fuel consumption, so we aim to fly with favourable winds. When the wind is favourable, fuel burn will decrease without losing speed. It’s not always worth it to get to the destination as fast as possible. Flying slowly - when possible - can save fuel considerably. Collaboration with air traffic control is a vital part for optimising fuel efficiency.
The most fuel-efficient way to land is the continuous descent approach. Over 90% of the approaches by Finnair to Helsinki-Vantaa airport are made with a continuous descent, in which the altitude is continuously decreased from the cruising level to the landing runway without level flight segments. Level flight requires more engine thrust, thus increasing fuel consumption and noise.
The passengers’ role
Every customer can impact fuel efficiency. It’s important to be on time at the airport and at the gate, so the flight can depart on time. The amount of baggage also plays a role. Will you pack three pairs of shoes, or just two? Will you pack a full size shampoo, or a small travel size bottle? If every Finnair customer had had 1kg less baggage in 2019, the fuel saved could have been used for 20 flights from Helsinki to Tokyo.