A verdict in a similar UK case has been postponed until the Australian ruling can be examined by the judge.

While the test case in the Victoria State Supreme Court does not have any direct bearing on the parallel attempts to bring airlines to the British courts, Australian civil caselaw is based on the UK system, so it is likely to be influential.

A group of UK families, just like the Australian victim, is claming that airlines failed to warn them of the risks of long-haul flights.

Australian case

The Australian ruling involved a 59-year-old man, Brian Povey, who was hospitalised and forced to give up work after suffering an attack of DVT he blamed on a three day return business trip from Sydney to London.

DVT is a potentially fatal condition in which a blood clot forms and blocks a deep vein, normally in the lower leg.

It can be brought on by long periods of immobility, and is often referred to as "traveller's thrombosis".

The man took both Qantas and BA to court, saying that the illness was not an "accident" as defined by the Warsaw convention - the international rules that govern the liability of airlines for any misfortunes which befall their passengers.

It's the first time in Australia - and the world - in which the interpretation of an accident has been argued in such a sophisticated way Paul Henderson, Australian lawyer

Airlines define DVT as something which happens to a passenger due to the "normal operation of an aircraft", which would make it an accident, and free them of any legal liability.

However, the Australian man said that airlines had failed to do enough to warn passengers about the risks of DVT on long-haul flights.

The full case - involving some 500 claimants - is now expected to go ahead next year.

The man's lawyer, Paul Henderson, welcomed the decision.

He said: "It's the first time in Australia - and the world - in which the interpretation of an accident has been argued in such a sophisticated way."

Cramped cabin

The claimants in the UK want to bring a case against 27 airlines which, they argue, did not properly warn them or their late relatives of the dangers of flying for long hours in cramped conditions.

The airlines involved in the UK action have said that, if the case were to proceed further, they would "vigorously dispute" any allegation that they were to blame.

A spokesman for BA said it would resist any claims against it, in the context of advice given by the government and the World Health Organisation that no specific link between flying and DVT had been established.

The airlines said they were protected under the Warsaw Convention from paying compensation for medical problems classed as a "passenger reaction to the normal operation of an aircraft".