Does anyone know how the flight deck computes the average speed?
After reseting the trip timer, which resets the average speed, I get "off results":
trip time: 1 hour
trip distance: 17.5 miles
average speed: 15.5 mph
trip time: 2.5 hours
trip distance: 40 miles
average speed: 16.5 mph
Both of these are off, one high, one low. Thoughts? Am I missing something mathematically basic?