Comforting Statistics and the Reality of Air Safety

In its latest assessment on the safety of air travel, the International Air Transport Association (IATA), a lobby group representing more than 230 airlines globally, proclaimed flying is so safe that if one were to take an airline flight every day it would be approximately 4,400 years before one would be involved in a fatal accident. (See Aviation Safety Journal, “Accident Trend Data Show Improved Safety Still Needed”)

Believing the above statement, flying then is much safer than open-heart surgery. If one were to undergo coronary surgery on a daily basis (with no complications from the previous day’s procedure), one would die on the operating table in less than one year.

The risk of open heart surgery is much greater than that of flying, but this is not as valid as comparing flying to other modes of transportation

The risk of open heart surgery is much greater than that of flying, but this is not as valid as comparing flying to other modes of transportation

Both in terms of time between accidents and operating room risks, these measures of air safety are misleading. The former misleads by racking up a hugely convenient denominator; the latter by comparing a perfectly healthy airline passenger to a patient with severe heart disease.

Safety across all modes of transportation is usually measured by the fatality rate per billion miles travelled. By this measure, airplanes do not score nearly as well as trains:

 rates

The comparison between airliners and passenger trains is apt because both represent very public forms of transportation, with government oversight and licensed crews. Comparing the safety of airline travel to automobile travel is really mixing the proverbial oranges and apples. Automobile travel is private, with varying degrees of driver alertness and competence and with highly variable maintenance of the vehicle (ranging from rigorous fanaticism on the part of some car owners to others not knowing what the amber “check engine” light on the dashboard signifies).

A train derailment, even at high speed, may be less catastrophic in terms of lives lost than an airplane crash from 30,000 feet, which usually ends with crumpled aluminum and bodies “commingled” – in the euphemistic phrase employed by accident investigators – with the wreckage.

Air crashes involve mass death that unnerves the public, as in the case of the 228 killed in the 2009 loss of Air France flight 447

Air crashes involve mass death that unnerves the public, as in the case of the 228 killed in the 2009 loss of Air France flight 447

The train travel statistic cited above is for all trains, globally. If high speed trains are singled out – Japan’s “Bullet” trains or France’s TGV – the air/train comparison is even more appropriate. High speed trains operate at roughly the same takeoff and landing speeds of airliners. In this respect, high speed trains are eight times safer, per miles travelled, than planes. Japan’s “Bullet” trains have operated since the early 1970’s without a single fatality (not counting the occasional despondent who commits suicide by throwing himself in front of a hurtling train). Similarly, France’s TGV, operating on special, fenced-off tracks, has never had a fatal accident.

High speed trains, like Germany's Intercity Express (ICE), are much safer than airliners

High speed trains, like Germany's Intercity Express (ICE), are much safer than airliners

Decades pass between accidents involving high-speed trains. If the aviation industry passes a year without a fatal accident, that is cause for self-congratulatory rhetoric about how the “enhanced commitment” to safety is paying off. In truth, a year’s gap between air crashes remains an anomaly worthy of mention.

The 2006 midair collision between a GOL 737 (shown here) and a business jet killed all 157 on the airliner. The accident reflects the positive and negative aspects of technology. Improved navigation accuracy meant the two airplanes, flying in opposite directions, could operate much closer together on aerial 'highways'. But the collision alert transponder on the business jet inadvertently was switched off, making an accident more likely

The 2006 midair collision between a GOL 737 (shown here) and a business jet killed all 157 on the airliner. The accident reflects the positive and negative aspects of technology. Improved navigation accuracy meant the two airplanes, flying in opposite directions, could operate much closer together on aerial 'highways'. But the collision alert transponder on the business jet inadvertently was switched off, making an accident more likely

The hard fact of the matter is that there has not been a step-increase in air safety since the advent of the gas turbine powerplant.

High speed trains are now approaching planes in the amount of power at their disposal. For example, the Acela Express train, operating in the Northeast Corridor of the U.S., features a locomotive at each end of a six-car articulated train set. The two locomotives provide over 12,000 combined horsepower – a lot for six passenger cars but necessary for quick acceleration and for maintaining high continuous speeds.

Comparing the horsepower of Acela’s electric motors to pounds of thrust in a jet turbine is slightly problematic, but 1 hp equates to approximately 75-110 pounds of thrust. The Acela musters close to the horsepower of a B747 jumbo jet, depending on the particular model jet engine selected. It should also be mentioned that modern jets feature a large amount of electric generation capacity to power ever more flight systems.

The Acela is a variant of France’s TGV high-speed train and has yet to experience a fatal wreck.

Accounting for the variability of weather, traffic, and other unique features of air travel, it would seem reasonable to establish a goal of, perhaps, one fatality per billion miles of airline flying. The rate of 1.0 is less than the current rate of 0.5 for all forms of train travel, and it makes much more sense than comparing today’s crash rate to that of yesterday’s. By this measure, even open heart surgery is safer today, as is just about everything else.

Current aviation statistics are clouded by big and misleading numbers (sometimes expressed in even more confusing powers of ten, as in 1 x 10-9). Comparing safety across modes of transportation is the only way to objectively and meaningfully quantify the risk of air travel.