Require everyone to pre-order meals, snacks and drinks so that the plane can carry just the right amount of food and drinks.

Reduce the amount of items on meal trays. Stock to the main and a piece of bread or a salad. No need for all these extra individually wrapped items, dessert etc.

Use real cutlery as disposable cutlery is not sustainable, not even wood.

Eco-paint is better for the climate.

Make a “code-share” cooperation with train providers, to allow for booking a ticket from A to B with combined train-plane modality and same benefits as connecting flight

Even if you have a few seats in business. The planes will be filled as usual while providing better service with almost no additional carbon footprint.