Jose wrote:
You have to apportion sunk costs to the hours you fly somehow or you
aren't calculating the true cost of flying.

The issue isn't the cost of flying, it's the cost of flying more.

exactly. It is called "incremental cost". It's the difference between flying
and leaving the airplane in the hangar. Assuming that the decision to own an
airplane was made independent from the decision to do angel flights, this
incremental cost is considerably lower for owners than for renters, true.

However, isn't it that the motivation for angel flights is largely "I want
to fly, and rather than just go for a 100$ Burger I could just as well help
somebody out while doing it". Viewed like this there isn't really much
difference whether you rent or own the plane you use for AF.

regards,
Friedrich