> However, better fuel efficiency resulting in cheaper flights leads to people flying more. That's bad. This part sounds complicated. It might be good for the

> However, better fuel efficiency resulting in cheaper flights leads to people flying more. That's bad. This part sounds complicated. It might be good for the people but bad for the environment. On the other hand, it probably also displaces some long-distance driving, and we have to estimate how much that is. Even if the environmental impact of reduced driving doesn't cancel out the cost of added flights, it's probably worth putting a value on the safety benefit. (Even though the current thread is about plane crashes, flying is overall much safer than driving, and reducing driving by even a little saves lives.)