Originally Posted by
Capt Pit Bull
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.
No it's not, if you simply define groundspeed as the component of velocity of the ground relative to the airplane's X axis, signed as positive moving nose-to-tail.
And don't act as if this is esoteric or meaningless, as we, conventionally, do exactly that with airspeed as I've pointed out a few times by now.