gps and ground speed
I always assumed that gps would give accurate ground speed. Is this the case? I have a new gps in the motor and it shows a -4mph discrepancy with the speedo. New motor (SAAB) so I would hope that the speedo is accurate.
I am interested both from the aviation point of view and the motor. 4 MPH ground speed over 2 hrs flying is not too much of a discrepancy I know but it is interesting.