Lesson bill = lesson base price that covers aircraft fixed costs (insurance, parking, landing fees, etc.)
+ fuel used ╳ fuel (daily/weekly) rate
+ oil used ╳ oil cost+ tacho/airswitch time ╳ hire rate which will cover variable aircraft costs such as maintenance, engine overhaul, etc.
+ VDO time ╳ instructor rate in flight
+ pre- and post-flight briefing time ╳ instructor rate on ground
where all the rates are transparent and worked out so that, in the end, a margin deemed adequate to run the business is yielded.
Stewth
I run a flying school, have done on and off for years, decades even. How about we charge VDO. It starts when the oil hits the switch and ends when the engine stops. For that you get me sitting next to you, a heap of free time briefing and debriefing and the use of my facilities, can't come much simpler than that.
Plus I charge flight test fees and flight review fees. Simple really, nothing hidden. Feel free to bring your own aircraft even.