Simon Calder: 'Travellers will have to take responsibility for the risk'

"If al-Qa'ida don't get you, the DVT will" is the view of one frequent user of Stansted airport. Such jaundiced sentiments obscure the remarkable safety record of aviation, and do not help reasoned discussion about the risks of flying.

The world's airlines, and in particular British Airways, were delighted with the law lords' ruling yesterday that they cannot be held responsible for cases of deep vein thrombosis among passengers. At a time when most airlines are struggling to make profits in the face of record fuel prices, the prospect of retrospective class actions could have proved fatal for some.

Airline passengers' needs are inherently contradictory. We demand - and currently enjoy - extremely low fares. Yet we also want plenty of personal space, particularly on long-haul flights. While DVT is by no means exclusively an "economy class syndrome", the restricted space offered in the cheap seats on long flights is far from ideal for those at particular risk, such as the elderly, women on the Pill and people who have recently had major surgery.

On flights to or from the US, the constraints are compounded by rules forbidding passengers from congregating in aisles - an example of how a move to reduce threats to security can increase the danger to individual passengers' health.

At least we are more aware of the risks than five years ago, when the first reports of "one death a month" among arriving passengers at Heathrow began to emerge. Quickly, the airlines stepped up advice and information for passengers, not least to minimise their exposure to legal action.

It speaks volumes about the cloudy relationship between airlines and the law that the defence team relied upon the interpretation of a treaty signed when commercial flying was in the aviation stone age: the 1929 Warsaw Convention. Seventy-six years ago, the formation of blood clots deep in the legs was simply not a concern of passengers in what was then a chronically high-risk business.

Since then, air travellers have earned a few more rights - enshrined in the 1999 Montreal Convention - but it appears unlikely that further claims against airlines over DVT will succeed. With aircraft builders battling over who can build the longest-range jet, travellers will have to continue to take responsibility for themselves. At least they can be thankful that flying is by far the safest form of mechanised transport.