But then you should probably only compare trips with somehow similar distances/times involved right?
Since I'm unlikely to fly my 20 mile commute to work, logging those miles under the "drive car" category isn't comparable, but is likely how I'd be in a car accident since that's something like 75% of my driving life. It seems you should only compare flights of 3 hrs vs car trips of 3 hours, or similar.
I’m not following. If I want to go visit my family 700 miles away for a holiday, I should most reasonably compare driving there with flying there as the risk choice is between those two manners of getting there.
Comparing flying for an hour vs driving for an hour isn’t a comparison between two substitute goods, unless the purpose of my trip was “to kill an hour”, making those valid substitutes.
Its normalized by distance, so the fact that 75% of your driving is short trips doesnt matter. You could argue that you need to look at only sustainable trips, but I think its unlikely to change the conclusion that per mile flying is safer than driving on a per mile basis.
You'd need to set some minimum trip distance for which flying is a viable alternative, like say 300 or 500 miles. Then throw out all the driving data for under that. Now, how would you expect this to shift the deaths/mile of driving?
In order to reduce it, driving short trips would have to be more dangerous per mile than driving long trips. I think this is unlikely to be true. Long trips often take place on highways at higher speeds and thus accidents have higher consequences. Drivers are more likely to be fatigued on longer trips. Drivers are less likely to be familiar with the roads on longer trips.
You've probably also got to throw out all flights for which driving is not a possibility. Like transcontinental trips. That may make flying appear safer since flights over oceans are more dangerous since there arent as many emergency landing opportunities.
> driving short trips would have to be more dangerous per mile than driving long trips. I think this is unlikely to be true.
I would be shocked to find that short trips were safer (per-mile) than long trips, as my intuition is that interstate highways are likely to be by far the safest type of roadway on a per-mile basis.
So I did some digging. It was surprisingly hard to find data that broke it down by roadway type, but I eventually found an article[1] that also linked to data[2].
Taking the most recent year available [2004], and converting to the typical airline standard (deaths per 10 billion miles travelled), urban interstates have a death rate of 57 deaths/10Bmi, urban collector roads 85 deaths/10Bmi, urban local roads 128 d/10Bmi, and rural local roads 315 d/10Bmi.
Airline figures for comparison are about 0.2 deaths per 10Bmi for scheduled commercial airline travel (Delta, United, Southwest, American, etc; not charter, not corporate, not general aviation), yet people are much more fearful of airplanes than automobiles on average.
Higher speeds does not necessarily equate to a more dangerous trip.
High speed delta to predominant flow is the more accurate metric.
Your fatigue comment is well received, but not a given either. A person may feel driving in a fatigued state is more acceptable for a short trip, but enforce more rigid limits on behavior for a long trip from home.
Since I'm unlikely to fly my 20 mile commute to work, logging those miles under the "drive car" category isn't comparable, but is likely how I'd be in a car accident since that's something like 75% of my driving life. It seems you should only compare flights of 3 hrs vs car trips of 3 hours, or similar.