Doncaster Sheffield Airport (DSA) has been voted the UK's number one airport by travellers, despite it being threatened with closure.
Owners Peel Group said DSA would begin "winding down" from 31 October as it was "financially unviable".
However, the airport has been praised by customers for "faultless service" for the fourth year in a row, according to a Which? report.
Almost 7,500 customers were asked to rate their experience at UK airports and DSA came out on top as travellers said it had short queues, friendly staff, and clean toilet facilities.
Sarah Barnes, GMB Union organiser, said that the airport is "an incredible transport hub, with huge scope for expansion" and it "needs to be saved".
She said: "Peel Group seem hell bent on getting as much cash as they can by closing the airport and flogging the site for housing.
"It makes no sense for any one but the Peel Group top. We cannot let them get away with it."
On Wednesday, Doncaster's mayor Ros Jones announced the council would be starting legal action against Peel Group to prevent its closure.
It comes after South Yorkshire leaders offered the owners public money to keep the airport open until a buyer is found.
Peel Group has been contacted for a comment.
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