Lawyers for a woman suffering from deep vein thrombosis (DVT) are preparing to launch a test case that could make airlines and aviation insurers liable for the condition in UK courts.

Watford-based legal firm Collins is currently building cases against several airlines after serving legal notices forcing them to reveal all the relevant documents they hold on the potentially fatal medical condition.

DVT is known to affect airline passengers, particularly those who have travelled on long-haul flights. Des Collins, senior partner at Collins, said he was working on a test case which he expected to come to court by early next year.

“We are at the investigative stage in attempting to bring a broadly representative case to the courts.”

It involves a woman prone to DVT who claimed an airline failed to prevent her condition from deteriorating, despite her warning the airline before she embarked on one of its flights.

Collins added that the airlines are basing their defence on an international treaty, the Warsaw Convention, which compensates passengers only for airborne accidents and not injuries resulting from in-flight incidents.