Andrew Gideon wrote:

My question: How do you decide what it costs to fly for an hour?

I know the basic idea is to accumulate all the variable costs and fit this
into the price somehow. But, as far as I can tell, this makes an
assumption: that each hour costs the same.

Each hour costs the same for only a certain period of time (usually one year).
You add up all the costs and divide by the number of hours flown that year.

George Patterson
There's plenty of room for all of God's creatures. Right next to the
mashed potatoes.