AIR travel has never been safer. According to the International Air Transport Association (IATA), an average passenger travelling on Western-built jetliners would have to take no fewer than 5.3m flights before being involved in an accident. To put that in perspective, even the most frequent of fliers is unlikely ever to rack up more than 20,000 flights over the course of a lifetime. The accident rate for the airline industry as a whole is now so low that someone taking a flight a day could theoretically expect 14,000 years of trouble-free flying.



One often-heard claim about air travel is that it is 12 times safer than going by train and over 60 times less hazardous than travelling by car. However, such statistics are a little misleading. Air travel is only the safest mode of transport when fatalities are calculated in terms of distance travelled. If deaths are counted per unit of time travelled, trains are every bit as safe as planes, and cars only four times more hazardous. Then, again, if fatalities are computed in terms of the number of journeys taken, cars and trains are respectively three times and six times safer than planes.



Clearly, comparing the safety of one form of transport with that of another is no simple matter. Cars have many safety features built into them these days, but there is only minimal oversight of how they are maintained and operated, and how well their drivers are trained. By contrast, trains have their own tracks and signalling systems, and are reasonably well isolated from other hazards in the environment. Meanwhile, planes are manufactured to the most exacting of engineering standards, their operations heavily regulated, and their crews given extensive training.



Apart from having different safety features to start with, each type of vehicle plays a different role in the overall mix of transport. And the risk involved in each therefore depends not only on its inherent safety, but also on how the vehicle is used.



Cars, for instance, are mostly used for trips measured in tens of kilometres; trains for a few hundred kilometres; and planes for hundreds or even thousands of kilometres. A typical journey by air might be the 4,000km trip from New York to Los Angeles. A typical car ride might be the 55km from Los Angeles airport to Disneyland.



In comparing the risks inherent in two such journeys, the 70-fold difference in distance between them makes flying marginally more dangerous than driving (when the risk is measured in terms of kilometres travelled). But people do not normally drive that far. Were they to do so, though, driving from coast to coast would take at least ten times longer than flying—and would be over twice as dangerous (when measured in terms of hours in transit).



Yet, once again, like is not being compared exactly with like. The plane may have 250 passengers and crew on board, while the car may be carrying five people at most. Thus, the plane puts at least 50 times more lives at risk but has a 60 times better safety record than the car (when measured on a distance basis). For the individual, that makes flying marginally safer. But if the plane should crash, it could kill 50 times more people than a car skidding off the road.



Of course, not all crashes result in fatalities. In aviation terms, an accident can be anything from a plane being damaged in some way, to people being injured or even killed. An accident so severe that the plane is destroyed, or has to be written off, is known as a “hull-loss”.



As the amount of passenger traffic changes from year to year, the safety statistics IATA and other aviation authorities are most concerned with are the annual number of hull-losses, and accidents per million flights. Over the past year, Western-built passenger jets were involved in just 0.19 accidents per million flights—less than half the previous year’s accident rate. Meanwhile, the number of hull-losses around the world was down to five from 11 the previous year.



According to the Aviation Safety Network, an independent database in the Netherlands, there were 23 fatal airliner accidents during 2012, with some 475 people killed as a result. That compares with a ten-year average of 34 accidents and 773 fatalities—making 2012 the safest year for air travel since 1945.



For that, passengers can thank the expertise that goes into the assembly, equipment and inspection of aircraft produced by the likes of Airbus, Boeing, Bombardier and Embraer. Western-built jets and turbo-prop planes account for around 95% and 80% of global passenger fleets respectively. Of last year’s 23 fatal accidents, only three involved Western-built jets.



Apart from better instruments, more rigorous maintenance and improved training, there are other reasons for this huge improvement in aviation safety. One is the voluntary reporting arrangement that encourages flight crew and maintenance staff to pass along, without fear of recrimination, details of mistakes that could affect a plane’s safety.



Another is the success of IATA’s operational safety audit. This was set up in 2003 to roll the various overlapping safety requirements that airlines have to comply with into one global standard for operating and maintaining a fleet of aircraft. Airlines audited by IATA—two out of three commercial flights now are—have half the accident rate of non-audited carriers. As a result, hull-losses are becoming increasingly rare in many regions of the world.



The most dangerous place to fly remains Africa. Though airline safety is improving practically everywhere, it is deteriorating there—and is now nine times worse than the global average. Two of the three crashes by Western-built jets last year (one at Accra and the other at Lagos) involved unaudited African carriers.



Unaudited passenger jets operating between big African cities are worrying enough. But the real problem of flying in Africa—and also in many parts of South-East Asia and in countries that were once part of the Soviet Union—remains the ageing fleet of turbo-prop aircraft flying into small, regional airfields with inadequate air-traffic control systems, and little regulatory oversight. The most pressing need is to get more of these turbo-prop carriers to embrace IATA's auditing programme. The few that have already done so were accident-free last year.



Recently, the Wall Street Journal reported that, for the first time since the Flight Safety Foundation, a lobby group based in Alexandria, Virginia, started collecting figures on aviation safety, there were more accidents around the world involving corporate jets than passenger planes. That is something for busy executives to ponder as they climb aboard the company Gulfstream. It is also something air-safety administrations need to pay a good deal more attention to.



That aside, can the huge strides made in aviation safety over the past decade continue? Modern passenger jets are stuffed with aids that make them nigh impossible to crash. Even so, there are dark mutterings about the increasing use of carbon fibre in their construction—to save weight and reduce fuel consumption. Some experts fear such composite materials may hold unpleasant surprises—in much the way that unpredicted failures caused by metal fatigue destroyed the reputation of the de Havilland Comet, the first passenger jet to go into production, in the 1950s.



Others express concern that the cockpit automation designed to make aircraft safer may overwhelm pilots with its complexity and undiagnosed bugs. But whatever direction future safety measures take, there is now no shortage of data about accidents. As tools for analysing big data improve, airline safety is likely to evolve from being merely a reaction to past mistakes to becoming a way of predicting and preventing future ones.