Thanks to both of you. I was of course aware that an aircrafts movement relative to the ground as wittnessed by an observer on the ground has no relevance to the aerodynamics involved. I also find it easy to imagine an aircraft standing still or travelling backwards if the groundspeed as a result of TAS-wind speed is 0 or negative. I somehow found it more difficult to resist the tempation to include "vectors" into the equation that somehow split the total velocity into two smaller vectors, one oposing the "current flow" and one pointing in the direction of travel. But of course, that too is a ground based observation.
I guess if the ship, or aircraft had an additional propeller acting on a different axis (like sideways) that would change the aerodynamics and result in a sideload on the aircraft much like tying the boat, a scenario where again the ground becomes relevant.
I guess relative wind is the term that explains it best and we have all had it explained to us at some stage. I guess sometimes trying to picture something can cause more confusion if one is not using the correct model.