Fuel is what you are paying for when it's not free
-1. Chartering is a little more obscure, in terms of breakdown of costs, but there's def an element of renting the jet, crew, and general overhead expenses. When we were looking for a jet for the principal of my company, the manufacturers were offering free demo flights, they said " the flight time is free, but you have to pay fuel at $xxxx an hour." Ie for the Dessault Falcon 900EX, it was $3,400 an hour, hardly a DDMS deal.