Not great, as it's passenger based there's no incentive to fly on a cleaner plane, or on a busier plane. A 747 that's only 25% full will cost the same as a 787

Not great, as it's passenger based there's no incentive to fly on a cleaner plane, or on a busier plane. A 747 that's only 25% full will cost the same as a 787 that's 99% full.