Fly from A to B, then back from B to A, where the wind is 90° across track ... and you will have a headwind in both directions ...
Which is why,
on average, flying random tracks, you are worse off when there is wind than when there is no wind....
I know a lot of people try to simplify these things in various ways, but basically the whole subject of correcting for wind comes down to the following:
- if there is no wind, you just head to the destination - simple!
- if there is wind, you have to pretend to be flying to a different spot, which could be before the destination, behind it, to one side of it, etc. And, because the wind is just a large scale movement of the air (a movement which the plane is totally unaware of) by the time you have reached the "fake destination" you will actually end up over the real destination because the wind has been moving you along. If you draw some diagrams, it is really obvious that
more than 50% of the time the "fake destination" will be
further away (in terms of ground distance) than the real destination.