Imagine filling your car with petrol as you drive at 70mph with the fuel coming down a hose from a tanker speeding in front of you that you have to line up with.
That’s something like what pilots have to contend with when refuelling - and in the air.
I saw this feat first-hand when the media were invited to join a flight powered by a blend of fossil fuels and about 43 per cent sustainable aviation fuel.
READ MORE: Historic RAF flight from Brize Norton powered by cooking oil
This significant flight was the latest in a series of milestones for the RAF towards a sustainable aviation future.
The aviation industry has pledged to achieve net-zero carbon emissions by 2050, while the Government has set a target of aircraft using 10 per cent SAF by 2030.
At 7am we passed through the departure lounge at RAF Brize Norton.
At 8am we took off bound for the North Sea.
The captain explained that we were going to be refuelling four Typhoons from RAF Coningsby.
We were travelling on the King's plane - the VIP RAF Voyager that usually transports government ministers and the Royals.
In 2020 it received a £900,000 makeover, including having a Union Jack painted on the tail.
People wonder whether the interior has changed too. I wouldn't describe it as uber luxury.
There were about 50 first-class seats at the front of the aircraft and a small galley where I was amazed to find that cabin crew would be looking after us with teas, coffees and a boxed cooked breakfast.
After about 40 minutes the Voyager put out a kind of towline, and four fast jets appeared on our left hand side.
Once we reached Area 8 the jets, travelling at around 300mph, started closing in on us midair.
The process is dangerous and highly skilled as the fighter aircraft has to match the speed with a huge transport aircraft.
Then, it has to maintain its position.
The hose has a basket on the end, and the combat aircraft has a probe, and once the pilot gets near suction helps them locks into the basket so that fuel can flow.
The process took about five minutes but depends on how much fuel is needed.
Although pilots have undergone rigorous training, it nevertheless remains stressful apparently.
But while they weren't exactly making small talk one of the jet pilots was casually fiddling with their helmet while all this went on.
Thirty minutes later the jets appeared again and what has been described as 'aerial ballet' started again.
Returning home we swooped down to 500 feet above the runway at Farnborough where an industry sustainable summit was taking place.
Then it was back down to earth at Brize Norton.
"Isn't that the coolest thing you've ever seen?" said an awe-struck fellow passenger.
It was certainly up there.
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