Can't you say "bon voyage" by plane?

In fact, it's just that taking off and landing can't be downwind

Because the speed used when the plane takes off and lands is airspeed, that is, the speed and relative airflow of the plane.

Under the same airspeed, the downwind will lead to a higher ground speed, which may cause the plane to run off the runway because the runway length is fixed. On the contrary, the same ground speed and downwind will lead to the decrease of airspeed, and the decrease of airspeed will lead to stall, which is equally dangerous.

Of course, downwind can save fuel, which is still very good.