This link leads you to a comprehensive review of deductions allowed by the IRS for charitable flights. the document was prepared by a law firm for the National Business Aviation Association. While the paper itself is focused on ways to increase the deductions that may be taken for charitable flights provided by corporate operators, the basic rules are applicable to ordinary GA charitable flights. The link is: http://www.dowlohnes.com/files/upload/C ... lights.pdf
The operative paragraphs reads as follows:
While the FAA now appears to permit aircraft operators to perform some charitable flights and
take the associated tax deduction, the IRS only allows a charitable deduction for variable costs of
transportation for charitable purposes.
“Only those expenditures incurred for operation, maintenance, and
repair, which are directly attributable to the use of such aircraft” on a charitable flight can qualify as
Examples of costs that could be “directly attributable” to a charitable flight include
(a) the cost of fuel and oil for the flight, (b) pilot fees incurred solely for the flight, (c) rental charges for an
aircraft used only for the flight, and (d) extra liability insurance incurred only for the flight.
Based on the aforementioned document, I don't think that IRS reimbursement rates for aircraft can be used as the basis for claiming a deduction for charitable flights. The document is pretty clear - only variable costs directly associated with a specific charitable flight can be deducted. I haven't been able to find any more recent guidance on the subject (this document was prepared in 2006).