To reduce emissions from flying, planes should slow down and extend flight times, according to new research conducted by the University of Cambridge in the UK.

In a report that sets out sustainable targets for the aviation industry, the university found that if aircraft flew 15% slower than current levels, fuel consumption would be reduced by 5–7%.

The report notes that a drawback of reducing speed is “the potential negative impact on airline productivity and passenger acceptance, especially for longer flights”.

However, it still encourages the measure to be implemented to make flying more sustainable.

Other measures proposed in the report include accelerated replacement of older aircraft with more up to date models and ensuring that more aircraft are used for route distances they were designed for.

Professor Rob Miller, director of the university’s Whittle Laboratory, said that implementing the new measures will require a “whole systems process change”.

Speaking to the Times, he said: “Airlines can’t do them alone, nor can the manufacturers or the airports. It’s not that anyone doesn’t want to. It’s just that the complexity of the system makes it very hard to do.”

Aircraft may have to be designed differently in the future to efficiently implement the new system. For instance, new planes could be designed specifically for short-haul flights of up to 2,000km; currently, the majority of short-haul flights in Europe are carried out by Airbus A320s and Boeing 737s, which both have a range of 6,000km.

“Aircraft that are designed to fly longer ranges are heavier and therefore less efficient. Designing an aircraft for the real-world journey it will operate will have a fuel-burn benefit and make it more efficient,” Miller said.

In other efforts to decarbonise, the airline industry has looked towards sustainable aviation fuels. However, questions remain over the cost competitiveness of these alternatives.