They said that the size of the Welsh government subsidy was unprecedented in UK aviation and a breach of competition rules.
Around half of the £205.2m subsidy is allocated for route development, which Bristol Airport argued could be used to unfairly entice airlines to Cardiff and distort the competition between the two airports.
But the Welsh government argued that it was common practice for airports to provide up-front payments to airlines.
In its ruling, published on Tuesday, the Competition Appeal Tribunal said: “Bristol’s application for a declaration, a quashing order and a recovery order is dismissed.”
“This judgment is unanimous.”
In welcoming the decision, a Welsh government spokesperson said: “We welcome the Competition Appeal Tribunal ruling that our investment in Cardiff Airport is lawful and can continue on its current terms.”
“The airport, which recently celebrated a 9% growth in passenger numbers for last year, is looking forward to its busiest summer flying programme in many years, and we very much hope to see both Cardiff Airport and Bristol Airport continue to thrive and grow.”
A Bristol Airport spokesperson said: “The competition tribunal heard significant concerns about the unprecedented £205m subsidy, which comes on the back of £181m of taxpayers’ money that Cardiff Airport has already received. The subsidy will see Welsh taxpayers forking out around £71 for every single additional passenger flying out of Cardiff Airport.
“We’re disappointed that the tribunal feels, that despite the burden being put on the taxpayer, the flexibility given by the Subsidy Control Act introduced after Brexit means that the subsidy can proceed.
“We’ll now take some time to study the decision in detail before deciding on our next steps.”
