Additionally they have recently introduced terminal navigation charges at regional airports that did not have such charges before.
Not to mention the fact they charge them when you fly VFR and the Airport has no operative navigation aids
Finally for the last 30 odd years there have been swingeing en-route charges levied on aircraft weighing more than 2 metric tonnes who file IFR. The cost of these charges is roughly equal to the profit margin on an Aztec or Baron charter flight.
When IFR I spend more on fees than on gas and the Aerostar is a thirsty animal. Certainly opting for filing SVFR generally, and will only switch to IFR enroute if the soup is too thick.
I am even considering trading down to a less safe airplane thanks to these idiots.