Switching to a smaller aircraft isn't necessarily good for the environment. For example the A319 burns 5%/less fuel than the A320 but has 15% fewer seats, in c

Switching to a smaller aircraft isn't necessarily good for the environment. For example the A319 burns 5%/less fuel than the A320 but has 15% fewer seats, in common configuration. So the per-seat emissions are worse than if they had sold the remaining A320 seats at cost