The Royal Air Force has completed a groundbreaking flight using only sustainable aviation fuel.
An RAF Voyager took to the skies powered by a fuel made up from used cooking oil, moving the service one step closer to achieving its 2040 target of being carbon neutral.
Flight Lieutenant Alex Gibb, OC Fuels Flight, RAF Brize Norton, told Forces News the fuel reduces a number of emissions, including carbon and nitrous oxide.
"Most of the fuels that we use, certainly in aviation, are fossil fuels," he said.
"Sustainable aviation fuel, this particular type, is made from used cooking oil.
"This reduces the carbon emissions from the aircraft by up to 80%."
But the benefits of sustainable aviation fuel are not just environmental, with the synthetic fuels holding the potential to reduce the RAF's reliance on global supply chains.
Air Chief Marshal Sir Mike Wigston, Chief of the Air Staff, told Forces News the service has already introduced a "50% fossil fuels, 50% sustainable fuels" blend into all their aircraft.
"This time last year, we flew the then-Prince of Wales, Prince Charles, on a Royal flight overseas using a mix of some sustainable fuel," he said.
"So we're already doing it.
"The issue is actually that there isn't enough capacity in global production.
"There are only a couple of sites in Europe – the UK hasn't got a production site for sustainable fuel yet, that's just being built now.
"So, it's actually a global supply issue, rather than anything that's holding us back in terms of our ambition," he added.
As well as being a UK first, Wednesday's voyage was also the first in the world to use fully sustainable fuel for a military aircraft of its size.
Defence minister Baroness Goldie described it as "a breakthrough moment" for the RAF.
She said: "The Royal Air Force has flown the UK's first military air transport flight using 100% sustainable aviation fuel on one of their operational Voyager aircraft.
"They should be rightly proud of this achievement – it is a breakthrough moment for the RAF and an exciting development for the Ministry of Defence (MOD)."