Originally Posted by
A Squared
Ummm, if a person in an airliner with a velocity of +500 knots is walking toward the tail at 1 knot, his groundspeed is +499 knots, not -499 knots
He's moving backward. His (body) groundspeed could not be in the positive unless he's running toward the tail at greater than 500 knots.
What's a Cessna's groundspeed when flying at 50 knots airspeed into a 60 knot headwind? Come aawwn!
Again, we're talking about the speeds of the
person not the airplane. The only way the airplane figures into this, is an enclosure of the 500 knot airmass.