> I'm not sure why looking at the incidents per trip would be preferable over looking at the incidents per mile.
Personally when enter a vehicle and start a trip, I'm interested in arriving at the destination alive, regardless of distance. If something bad happens, whether I die 1km into it, or 10.000km into, is quite pointless. So incidents per trip probably conform better to how people evaluate travel risks.
Exactly, so when I get in that car, I want to know the probability of dying. How do you compute this? By taking the number of crashes per kilometer, and multiplying by the number of kilometers you'll drive for. A trip of 5000km is less safe than a 5km one. That's just common sense. Similarly, when comparing flying versus driving from Amsterdam to Paris, you are, as you say, interested in which method is most likely to get you to your destination alive. So you take the number of incidents per kilometer for planes and cars, and multiply them by the distance between Amsterdam and Paris. The interesting figure really is incidents / kilometer, that's just basic math.
> taking the number of crashes per kilometer, and multiplying by the number of kilometers you'll drive for. A trip of 5000km is less safe than a 5km one.
When comparing a difference of 1000x, sure its probably safer.
Your premise is wrong though, it isn't common sense to take a generalized statistic like deaths per km and extrapolate that to be the correct estimate for any particular trip.
The statistic loses all context of differences in vehicles, road conditions, time of day, specific roads, etc. The stat is a great example of how a statistic seems meaningful to get a big picture but is completely useless to us as we can't make any decisions based on a number that is so generalized as to lose all context and meaning.
Assuming that the survival rate is constant as a function of trip length, the empirical estimate of the risk is fully determined by the number of deaths per distance.
> Assuming that the survival rate is constant as a function of trip length
That's an assumption that doesn't hold up, at least that's the argument I was trying to make above.
Generalizing so much data down to a single statistic makes the number useless. Almost all context is lost, really the only context kept is mode of transportation and distance traveled. That isn't enough to help anyone make a decision for any particular trip.
However the risks aren't necessarily proportional to miles travelled.
So for example with flights - I'd imagine the most dangerous parts are the take-off and landing - which happen once per trip no matter how long you fly for inbetween.
So for flights incidents / kilometer are perhaps misleading.
The other key point when comparing car stats to flights is car stats include pedestrian/cyclist and motorcyclist deaths which make up perhaps around half of the deaths.
Yet I suspect the people in twin towers weren't included in airline death stats.
Sure there isn't a perfect single metric - just pointing out that the one the airlines prefer appears to be biased towards air-travel.
The other factor that is often ignored is the issue of control. As a passenger of an airline you have very little impact on the chance of an accident - you are just an accident statistic.
Whereas if you are driving, your own driving behaviour, choice of car, route etc puts you more in control of the chances ( though of course by no means completely ).
This has a big impact on the perception of risk ( as more than average think they are better than average :-) ).
A frequent flier is still more likely to die in a car accident than airplane crash. Hell, even airline pilots are more likely to die driving to work than in their planes. You have to get to risky GA practices before the risk of dying in the plane dominates the normalised terror that our roads are.
Unsafe air travel has been regulated out of existence in the best regions. Piloting a small airplane in a random country is still dangerous though. Unfortunately it is hard to avoid doing the equivalent in a car.
In theory it would be possible to create a safe driving car that would avoid unsafe roads, conditions, mental state, amount of driving, driving practices, speeds, distances etc. But a lot of the time it would just end up not being compatible with the road system and owning a car. And it still wouldn't totally prevent an accident, especially not caused by anyone else.
> Piloting a small airplane in a random country is still dangerous though. Unfortunately it is hard to avoid doing the equivalent in a car.
As someone who does both, the former is still controlled in a way we just don't do for cars.
Note that the moment we go to countries that are actually willing to take people's driver's licenses (and put them in jail when they drive without one, the way you'd expect to be treated flying a plane unlicensed), the safety statistics change. The only way we're getting that in America, however, is with self-driving cars.
> How often do you fly and how often do you drive by car
I think I fly on average a bit more than once every two weeks. I'm in a car about every day, mostly for short trips--in the last month I probably spent about as much time in a car as in a plane. Pilots probably fly more hours than they drive.
You really have to fuck with the statistics to get driving to come anywhere close to commercial aviation in terms of safety, they're so far apart.
> If you take the area where you drive into consideration the death numbers change, the same is valid for the drivers behaviour
Source?
> You can't influnce that when you fly
Whether you can influence a variable doesn't change its order of magnitude. Unless you're driving on a closed track at low enough speeds that if you pass out you'll be fine, you're safer flying than driving.
That might be true for most and is a reasonable way of looking at it.
But if someone is going on a 10,000km trip and trying to choose between modes of travel, the mode with the fewest incidents per mile will be the safest way.
Personally if I'm about to go on a 500 mile trip and choosing between modes of transport on safety grounds, I'd pick the one with the highest chance of surviving that trip, which ceteris paribus is the one with the fewest incidents per mile, and not make the error of assuming that the risk of a 500 mile car journey is equal to the risk of the average 10 mile car journey the per-trip stats are based on.
(Complications like takeoff and landing might actually make a 10 mile commercial flight riskier, but that isn't an actual option. The 500 mile flight is going to work out safer in almost all circumstances though)
Travel can be necessary or discretionary. The per-mile safety is the relevant number when the travel is necessary, but if it’s discretionary, then I might choose to just stay home if the numbers (price, time commitment, missed events back home, death risk…) don’t seem that great.
Sure, but if you're evaluating the risk of a discretionary trip the crude per mile safety of the transport mode (multiplied by the specific trip mileage and adjusted by any other risk factors you're aware of) is still the correct starting point for estimation and the crude per trip estimate across all journeys undertaken by that mode of transport raised upthread still unambiguously the wrong one (especially if there are vast differences in average trip lengths like between aeroplanes and cars)
Personally when enter a vehicle and start a trip, I'm interested in arriving at the destination alive, regardless of distance. If something bad happens, whether I die 1km into it, or 10.000km into, is quite pointless. So incidents per trip probably conform better to how people evaluate travel risks.