How Safe is Flying?

I’ve often heard it said that “flying is the safest form of travel”. Here’s a statistic which proves it:

Fatalities per 100 million Passenger Kilometers
Mode Fatality Rate
Air 0.05
Bus/Coach 0.1
Rail 0.1
Van 0.1
Space Shuttle 0.3
Car 0.3
Water 1.0
Bike 4.3
Walking 5.4
Motorbike 9.9

According to this statistic flying in the space shuttle is safer than walking. That doesn’t sound right to me. The Space Shuttle has made 127 flights, 2 of which have killed all the passengers. The statistic, though true, does not represent human perception of risk very well, since it measure fatalities per distance. The space shuttle travels a very long way during each trip, so the statistic makes it appear safe. To a lesser extent the same bias applies to air travel, since a typical plane journey is over a long distance.

There are other statistics for measuring the safety of travel:

Fatalities per 100 million Passenger Journeys
Mode Fatality Rate
Bus/Coach 0.5
Van 1
Rail 2
Car 4
Walking 4
Air 12
Bike 16
Water 34
Motorbike 115
Space Shuttle 2000000
Fatalities per 100 million Passenger Hours
Mode Fatality Rate
Bus/Coach 1
Air 3
Rail 4
Van 5
Car 13
Water 18
Walking 22
Bike 53
Motorbike 382
Space Shuttle 8800

Both these statistics provide a much more human-realistic measurement of risk. I suspect that most folks would think of risk as “fatalities per journey” or “when I make a journey by x how likely am I to die?”. Personally I favour “fatalities per hour”, the physicist training just makes risk per unit time seem like the right thing to measure. In both these statistics air travel is no longer the safest form of travel.

However you look at it riding a motorbike is relatively dangerous. But just exactly how dangerous is “382 deaths per 100 million hours”. Well, say you commute to work on your motor bike: its a half hour journey each way, you commute 220 times per year for 40 years. That gives you a 0.067 or 1 in 15 chance of dying during your commute over the course of your career.

The majority of the data here is taken from the Department for Transport website, and considers fatalities rates during the late 80’s and 90’s. The data for the Space Shuttle is from the NASA website, and the analysis is of the first 117 flights of the shuttle (1981-04-12 to 2007-06-08).

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