Per mile isn't really that good a measure for either flying or driving, because the risk of both flying and driving depends on where the miles are.
For driving, the risk is much higher in cities on surface streets than it is on freeways between cities, for example. So a 10 mile round trip to the grocery store and back would probably be orders of magnitude more dangerous per mile than an 800 mile round trip from Los Angeles to San Francisco and back.
But your chances of dying on the grocery store trip and your chances of dying at one of the ends of your LA/SF trip would be roughly the same.
Same with flying. Takeoff, climbing to cruising altitude, cruising, descending for landing, and landing all have different risk profiles. A long trip is much safer per mile than a short trip because most of it is spent cruising at high altitude which is the safest part of the trip, but the overall risk is usually going to be higher on the long trip.
Driving is further complicated because you have a lot more control over your safety when driving than you do when flying. When I've flown from LA to SF, it was probably about the same risk no matter what time of day I went.
When I've driven from LA to SF, I've generally been able to pick times of day when there was little traffic at the ends, and there were generally no other cars within a couple miles of me on the freeway. That should have put my risk way below the average driving risk. (Note: I am not claiming that I am a more skilled or safer driver than average!).
It was still probably more risky than flying, but not orders of magnitude more risky.
For driving, the risk is much higher in cities on surface streets than it is on freeways between cities, for example. So a 10 mile round trip to the grocery store and back would probably be orders of magnitude more dangerous per mile than an 800 mile round trip from Los Angeles to San Francisco and back.
But your chances of dying on the grocery store trip and your chances of dying at one of the ends of your LA/SF trip would be roughly the same.
Same with flying. Takeoff, climbing to cruising altitude, cruising, descending for landing, and landing all have different risk profiles. A long trip is much safer per mile than a short trip because most of it is spent cruising at high altitude which is the safest part of the trip, but the overall risk is usually going to be higher on the long trip.
Driving is further complicated because you have a lot more control over your safety when driving than you do when flying. When I've flown from LA to SF, it was probably about the same risk no matter what time of day I went.
When I've driven from LA to SF, I've generally been able to pick times of day when there was little traffic at the ends, and there were generally no other cars within a couple miles of me on the freeway. That should have put my risk way below the average driving risk. (Note: I am not claiming that I am a more skilled or safer driver than average!).
It was still probably more risky than flying, but not orders of magnitude more risky.