HarryC, post 209
Well that is certainly food for thought!
If there is NO sidewind against an aircraft, that would imply
- All the force vectors linked in post 189 are wrong;
- The force vectors referenced in 201 are wrong;

And if the wind is always aligned with the aircraft, with no side wind, then the following scenario would have to be true.

- Lets start the plane flying North, into a North wind. Airplane and wind are perfectly aligned.
- The plane turns a little, lets say 15 degrees. The apparent (not true) wind is still aligned with the aircraft
- At 90 degrees, the true wind is straight from the side; but the frame of reference makes the wind still aligned with the airplane, and it should still be coming from in front on the nose
- Let now turn a total of 120 degrees. The wind is coming from behind the plane. Is the apparent wind still coming from in front of the plane?
- Let's complete the turn, at 180 degrees the plane is going in the same direction as the wind. Seems like the true and apparent wind and aircraft are aligned, but now the wind is on the tail.

For there to NEVER be a crosswind, somewhere around 90 degrees, the apparent wind would have to switch from on the nose to on the tail...

It could happen I guess.