You're booking a flight with two carriers to choose from: a new-to-the-market "no frills" airline and an established but more costly one. You've compared prices, departure times and in-flight menus. You think you've done all your research but does this question cross your mind: which flight is more likely to crash?

If not, it should, says Andrew Weir, an investigative journalist and researcher for the recent Channel 4 Black Box documentary on airport crashes, who is making a habit of asking awkward questions of the air transport industry.

Consumers today are more safety-conscious about everything from the food they eat to the road-worthiness of their cars, yet, when it comes to air travel, the only health effect generally considered is whether to take a smoking or non-smoking seat on flights where that's an option. But such complacency is misplaced, argues Weir in The Tombstone Imperative: The Truth About Air Safety, a new edition of which is published this month. Far from being vigilant in ensuring that safety is paramount, he claims, airlines and regulators are bent on spending the minimum to meet requirements.

"Unnecessary costs are the enemy of profits, and safety measures increase costs without increasing revenue," he states bluntly.

The principle by which the industry operates is, in his view, encapsulated in the words of a US aviation official who said "we regulate by counting tombstones". The "Tombstone Imperative" means this: safety changes are not introduced until enough people have been killed to warrant them.

First published last year, the book has been updated with new material on the Concorde disaster which, says Weir, was a perfect example of the industry's reactive approach to safety at work.

Two decades before last July's fatal crash in Paris, the Concorde was involved in an almost identical incident. A burst tyre on takeoff sent heavy shards of rubber into the body of the plane, peppering the left wing with 14 holes and penetrating three fuel tanks. The flight crew had been unaware of the damage until a passenger brought it to their attention and, tellingly, it took him some time to convince them there was a problem.

Having been told not to worry and that the damage was normal, the passenger described how he had to drag a disinterested crewmember to his seat "and virtually held his head over the window so that he could look down and see the hole in the wing. When he saw the hole, he exclaimed, `Mon Dieu'. "

The only thing which distinguished this incident in June 1979 and last summer's crash was the fact that the leaking fuel did not catch fire and, as a result, the plane was able to make an emergency landing.

Weir cites five other potentially catastrophic fuel leaks with a similar cause in less than 80,000 Concorde flights. While the operators did what they could to prevent further tyre-bursts by strengthening the wheels and using thicker rubber, Weir notes they did nothing to protect the wing but rather "decided to cross their fingers" and hope for the best.

He claims such "indifference thrives on a lack of public interest" which airlines and regulators have fostered through bland assurances on safety and guarding information from public scrutiny.

Their success in limiting criticism can be found in the widespread acceptance of the industry mantra that air travel is the safest mode of transport. To support the claim, statistics are cited showing fatalities per kilometre are three times higher for rail travel (0.10 deaths versus 0.03 deaths per 100 million km). But, Weir argues, because aircraft travel huge distances and the risk of an accident is concentrated on take-off and landing a more accurate measurement would be fatalities per journey. By this standard, air transport fares worst: 55 deaths per 100 million passenger journeys, against 4.5 for cars and 2.7 for trains.

Moreover, he warns that although the number of air fatalities a year has levelled off at around 1,500, after peaking in the 1980s, it is set to grow again in line with a projected annual seven per cent increase in commercial air travel. In 10 years' time, on present traffic growth rates, twice as many people will die in air crashes as today. Weir has attracted strong criticism. David Learmont, operations and safety editor of Flight International Magazine, says he would not particularly object to Weir's critique of the industry "if the reality was not almost the opposite. The air industry is more scrutinised and has more checks and balances than any other."

Commercial motives are present in every industry, Learmont points out, and with air transport they work in favour, not against, safety. "If an airline is privatised the worst thing they can do is start cutting corners because if they have an accident (a) their shares will crash and (b) people will go to other airlines." He cites the example of Korean Air whose reputation became so damaged by crashes that it lost its strategic partner Delta and suffered massive financial losses.

Lilian Cassin, the Irish Aviation Authority's corporate communications officer, agrees, claiming "safety is the cornerstone of the industry". Warning against "scare-mongering", she says there is a danger members of the general public might perceive risks when there are none.

The authority has received numerous complaints, for instance, about Dublin Airport's single-runway status, which means aircraft have to depart and land in the same space. "There is nothing unsafe about this. A very, very busy airport like Gatwick operates a singe runway too."

She rejects Weir's claim that budget or "no frills" airlines are somehow less safe than established ones, saying: "Airlines have standards to meet and they either make the grade or they don't."

The authority, which oversees aircraft licensing in the State, receives about 700 reports of incidents a year out of 819,000 flights. The most serious incidents are examined by the Department of Public Enterprise's air accident investigation unit (AAIU), which normally deals with about 80 cases a year, six to 10 of which involve public transport aircraft.

As regards causes, the Irish experience mirrors the international one which shows 70 per cent of crashes are caused primarily by crew error, 11 per cent by aircraft defects, and about five per cent each by poor maintenance, weather and air traffic control.

A particular problem in Ireland, says Graham Liddy of the AAIU, is incidents around the ramp areas of airports, especially Dublin Airport. "There are more commercial pressures and a higher growth in business, and the infrastructure has not kept pace."

Concern, he says, is rightly expressed about moves towards creating "virtual airlines" whereby all services, including pilots and maintenance staff, are employed on a contract basis from the lowest bidder. There is a worry, he says, that it will lead to a loss of some of the accountability and safety-ethic that can be found in strong corporate regimes.

But he rejects the claim that low-fare carriers are contributing to a decline in safety standards. "To date, statistically there is no indication that low-cost airlines operate to a lesser standard than the big guys."

Weir disagrees, however, and cites a 1997 US government agency report showing new airlines, especially low-cost ones, had significantly worse accident and incident rates than more established ones. Before reading too much into this from an Irish point of view, however, one should bear in mind Weir also warns travellers against airlines which contract out their maintenance, have financial difficulties that might lead to cost-cutting, or are blighted by industrial relations problems.

Consumer groups in the United States are now campaigning for carriers to be ranked according to safety by aviation authorities and, with added pressure, Weir believes this will happen, in spite of strong objections from airlines. He says "the aviation industry seems to think it is `safe enough'. But improvements are feasible and possible, provided the public pressure to implement them is there."

The Tombstone Imperative: The Truth About Air Safety by Andrew Weir is published by Simon and Schuster tomorrow, £6.99 in UK.