> I would say the most sensible is "per passenger hour", followed by "per passenger mile" Not trying to be contrarian or anything but I'm curious why. Another

> I would say the most sensible is "per passenger hour", followed by "per passenger mile" Not trying to be contrarian or anything but I'm curious why. Another comment mentioned the material difference in available options between comparing an 8 hour flight to an 8 hour drive. In my mind, the only meaningful metric then would be the "per passenger mile". This should be emphasized by the fact that there are destinations that literally no amount of driven miles will get you to. The utility provided from 8 hours of flight versus 8 hours of driving are so drastically different I can't imagine how you'd compare them. 8 hours of flight will let you visit roughly a quarter of the world. 8 hours of driving won't even get you a quarter of the way across the US.