41 CFR § 301-10.302 - How do I determine distance measurements for my travel?

§ 301-10.302 How do I determine distance measurements for my travel?
If you travel by The distance between your origin and destination is
Privately owned automobile or privately owned motorcycle As shown in paper or electronic standard highway mileage guides, or the actual miles driven as determined from odometer readings.
Privately owned aircraft As determined from charts issued by the Federal Aviation Administration (FAA). You may include in your travel claim with an explanation any additional air mileage resulting from a detour necessary due to adverse weather, mechanical difficulty, or other unusual conditions. If a required deviation is such that airway mileage charts are not adequate to determine distance, you may use the formula of flight time multiplied by cruising speed of the aircraft to determine distance. You must convert nautical miles to statute or regular miles when submitting a claim (1 nautical mile equals 1.15077945 statute miles).
[FTR Amdt. 70, 63 FR 15955, Apr. 1, 1998, as amended by FTR Amdt. 108, 67 FR 57965, Sept. 13, 2002; FTR Amdt. 2005–05, 70 FR 61046, Oct. 20, 2005; FTR Amdt. 2010–04, 75 FR 59095, Sept. 27, 2010]