Originally Posted by
Jet_Fan
no, it's -499 because he is facing the tail. If he stops it goes back to -500. If he turns to face the cockpit while stationary it goes from -500 to +500 almost instantly.
This, and everything else resting upon it, is total bollocks.
Groundspeed is a Scalar. An objects ground vector is comprised of its ground speed and its track.
When an aircraft is heading directly into a wind that exceeds the TAS then it's track is the reciprocal of the heading.
If you try and call that a negative ground speed you are taking account of the same thing twice.