|Quoting Viv (Reply 2):|
No, because airspeed does not increase in a tailwind (or decrease in a headwind).
That's right, and actually, the opposite happens. God forbid I bring out the conveyor belt loonies again, but I hope we can agree on this. If, at some place on the surface of the Earth, the wind blew as fast as the speed of sound in those particular conditions, an observer standing there would experience winds at the speed of sound (not a good idea).
Extending the concept a little, if an airplane was crusing in still air at, say, mach .75, or 75% of the speed of sound in those conditions, and a sudden current of wind came by, aimed directly at the nose of the plane, aligned with the fuselage, at least as fast as 25% of the speed of sound, it would suddenly be flying through the air faster than the speed of sound. Not being designed for it, and not having the power to sustain flight at those speeds, it would experience a violent deceleration. Most planes would probaly sustain significant structural damage. Fortunately, even in turbulent air, it's highly unlikely that winds on Earth will ever change quickly enough in a short enough time to make this happen.