Neil Gould wrote:
Yes, but that usage renders 61.113 (c) meaningless without some
additional parameters. One can calculate many things precisely, even
without the use of a calculator. ;-) That might not guarantee
compliance with the FARs.


Pro Rata means a specific thing. It is well defined in law and common usage.
In 61.113 (c)the regulation is quite clear. A pilot may not pay less that
his pro rata share of the allowable expenses.


Now in the case of a plane rented wet it is easy (Rental price +
airport fees)/pax. If on the other hand I'm in my plane and I know
the cost of flying includes things like overhaul and maintenance
prepaids I have to deduct those before I do the math as the
regulation specifically says that I can only pro rata the fuel, oil,
airport expenditures and rental fee.

The cost of maintenance etc. is typically factored into a rental fee.
But, I think the purpose of 61.113 is to set guidelines for what might
constitute compensation. You and other travel to a work site, they can
share the cost of fuel, oil, airport expenditures and rental fees.
They can't pay you for the use of your plane and have you ferry them
about, so the closer the financing looks like that's what is going
on, the more likely one is to violating the FARs.


The purpose of 61.113 (c) is to set the items than can be shared pro rata
among a private pilot and his passengers. And it does it very well.



I'm curious where you get the 51% rule?

As has been mentioned by others, the 50% figure has been taught and
tossed around for quite a while. I don't know if its origin is
formal, was established by precedence, or just common practice. I
would be happy to find out that my company could pay the entire cost
of a flight without it becoming an issue of compensation, but that
seems a long shot unless someone can show evidence that it is an
acceptable practice. Do you know of any such evidence?

Neil


Not a long shot at all. Just read 61.113 (b). Not only can the company pick
up the tab they can pay you while you are doing it.