GetFlightTrack: Groundspeed


#1

Hi all… Quick question on ground speed: What does this actually measure?

I have tried to calculate the average ground speed of a flight by taking the time between departure/arrival runway actual times and adding up the distance between all the position data delivered by GetFlightTrack. Did a sense check by comparing this to the great circle distance for the flight - so the average ground speed I calculated should be correct.

However when I search GetFlighTrack feed for the highest recorded ground speed this turns out to be a little less than the average I calculated - which clearly is impossible. So I’m wondering if maybe your definition of ground speed is different from what I expected?


#2

Groundspeed is the instantaneous calculation between the current and last position, which will not reflect overall average rate.

Also keep in mind that the groundspeed is measured in knots (which is based on nautical miles per hour) and that may be the source of your calculation differences if you happen to be using statute miles in any of your conversions.


#3

Thank you very much, bovineone! I have adjusted my calculations to knots and everything works fine now!