Okay, so I want a fixed price on departing passengers when an aircraft takes off. Say for example, $58.00 for an international passenger, and this feature could also bring connecting flights. They would be charged less as they fly twice through your airport.
Why it should be implemented:
It would bring realism to the game and promote larger passenger aircraft such as the 747 or A380.
How it would be implemented:
In the fees panel, you would be able to change this fee with the slider. The airline then would be charged that number times the number of passengers on board.
I don’t really understand what you want and to change and why. As @RubenGass mentioned, every passenger pays (default 15$) when he/she/it leaves or enter the plane.
If you buy a flight ticket, the ticket price contains normally following:
single route price which the airline charges for their operation
airport taxes from origin airport = departing passengers, default ACEO value $15
airport taxes from destination airport = arriving passengers, default ACEO value $15
tons of other fees depending on country, airport etc. for example noise fee, tourism fee and whatever