Sometimes we don't need the cream and toothbrush; sometimes a pair of socks is sufficient. Being able to customize the amenity kits in advance reduces waste.

I would use my skills in optimization and deep learning to learn what frequenzies and time schedules that maximizes the load factor of each aircraft in the fleet.

Use powder soap instead of liquid soap in all lavatories, powder soap is much lighter thus reducing wieght.

Separate the salt and pepper from the rest of the table set. Way too often it's just thrown away.

Reusable coffee cups for take away coffee and in-flight.

Instead of opt-out for food on the plane plane that is included in ticket, make it opt-in.