More time on the plane? Swiss should fly slower - here's why

A new study by Cambridge University suggests reducing flight speeds in order to save kerosene in air traffic. Swiss is not so keen on the idea.

It is flying as if the coronavirus pandemic had never happened: Swiss achieved record sales and profits in 2023. The number of passengers is also likely to increase this year.

At the same time, many airlines are investing in sustainability - driven to a large extent by the fear of impending flight regulations and higher taxes.

A new study by the University of Cambridge has now proposed how the industry could immediately improve its emissions balance: According to the researchers, airlines would burn up to seven percent less kerosene if they reduced their speed by 15 percent. This target should be taken into account when building future aircraft.

Flight times would be significantly longer

The disadvantage for passengers is that flight times would be longer. According to the Cambridge experts, a flight across the Atlantic would arrive 50 minutes later. This in turn is likely to reduce airline productivity. However, the researchers believe that increased efficiency at airports with shorter waiting times could offset this disadvantage.

The idea of reducing flight speeds in order to save kerosene is not new. The then CEO of Swiss, Harry Hohmeister, commented on this topic back in 2012. He pointed out that although slowing down could reduce fuel consumption, it would also disrupt the entire flight schedule.

According to spokesperson Michael Stief, Swiss is already focusing on optimal speed planning, as reported by the "Aargauer Zeitung" newspaper, which takes into account various factors such as handling time windows at airports in order to minimize CO2 emissions.

Speed reduction is counterproductive

However, the airline considers an across-the-board speed reduction of 15 percent, as proposed by researchers at the University of Cambridge, to be counterproductive. Stief explains that this would lead to increased aerodynamic drag and thus to an increase in CO2 emissions.

Swiss relies on dynamic flight management. During the flight, altitude and speed are adjusted taking into account current weather and wind data in order to optimize fuel consumption. The airline also uses modern IT technology to precisely calculate kerosene requirements during flight planning, the newspaper continues.

Reducing speed is not the only proposal that the Cambridge researchers have for reducing environmental emissions to zero by 2050. They do not believe that the target can be achieved with the measures launched and announced to date. According to the study, aviation currently contributes 4 percent to global warming, with 2.5 percent attributable to CO2 emissions alone.

Sustainability is not always a priority

Stief points to further optimizations: "When taxiing to the runway, we only start the second engine at a later time, but in good time to be ready for the take-off run." The descent and approach are flown with the engines idling as far as possible, and the cockpit crew ensures that the lift aids for landing have low drag. "After landing, we switch off the engines that are not used for taxiing after the cool-down period."

However, the case of the new cabin shows that sustainability is not always a top priority at Swiss. This is to be installed in the long-haul aircraft from 2015, but the luxurious First Class seats - including seat heating and cooling as well as an XL TV screen - are so heavy that lead plates will have to be installed in the rear section of 14 A330 aircraft to balance them.

We are talking about 1.5 tons, which immediately reduces the positive effects of a speed reduction.