Free reebooking to earlier flight when avilable. Result in filling up seats, and making it more likely to fill up seats on later flights

Reduce business class

Better food = less food waste. I see a lot of boxes not being emptied. So make sure it's good quality food to most peoples liking. Keep it simple and good

Not handing out napkins under every drink.

Establish additional partnerships with other airlines on specific routes to, for example, consolidate two half-full flights into one fully-booked flight.

Allow users to visualise their travel carbon footprint in-app. Include everything such as transportation to/from the home and destination, hotels.