HVDFA Odometer Correction Factor

The Hudson Valley Direction Finding Association's hidden transmitter hunts make use of an Odometer Correction Factor (OCF) in calculating a team's actual elapsed mileage in the hunt.  Correction of a vehicle's indicated mileage has been found appropriate where a small difference in mileage covered may affect the order of finish in an event, as has happened several times in HVDFA Fox Hunts. A vehicle's indicated mileage can be affected by its speedometer and odometer calibration, but more frequently by variations or alterations in tire size and tire inflation pressures, as is well known to Automobile Road Rally enthusiasts.

The Odometer Correction Factor will be calculated for each vehicle that regularly participates in HVDFA events, and is intended to indicate how a vehicle's indicated mileage must be corrected to arrive at its actual, true mileage. The Factor will be computed according to the following formula, and will be indicated to 3 decimal places.
 
 

Several methods can be used to measure a vehicle's OCF.  One that has been considered acceptable by HVDFA is to use a Global Positioning System (GPS) satellite navigation receiver having a TRIP ODOMETER function to measure the mileage actually driven by a vehicle over a route of at least 10 miles.  The vehicle's indicated elapsed mileage is then divided by the true trip mileage, as measured by the GPS unit, to give that vehicle's Odometer Correction Factor.