PARIS—Qatar Airways said on Monday it had started proceedings in a UK court against planemaker Airbus in a bid to resolve a dispute over skin flaws on A350 passenger jets, bringing the two sides closer to a rare legal showdown over aviation safety. The companies have been locked in a row for months over damage, including blistered paint and corrosion to a sub-layer of lightning protection, which Qatar Airways says has now led to the grounding of 21 A350 jets by its domestic regulator. Airbus insists the carbon-composite passenger jets are safe to fly despite some “surface degradation,” while Qatar Airways says it is too early to say whether safety has been compromised. The dispute came to a head last week when Airbus, in what experts called an unprecedented move, accused the Gulf airline of misrepresenting the problem as a safety issue and threatened to call for an independent legal …