some say it is; others dont. the1s say it is, say they face it with their planes, and are willing to bet their lives for it.
and i think that both are correct.
how could that be?
lets start with this fact: things are relative. it depends on which kind of planes are they talking about.
those who think there is, fly slow, low wing loading airplanes. large and light.
the others fly fast, heavy planes. mmhhhh...
a fast/heavy plane does not care about the wind intensity or direction.
a slow/light does.
could that be the reason why the 1s that fly fast/heavy think that there is not such a thing?
i would like to watch those who dont think it is, flying a light piper cub style plane in turbulent/windy weather and try a downwind turn near the ground on the approach and hear what they say

First consideration : I have not seen many heavy planes flying well, but light ones many many.
Second consideration : given the plane geometry and size, the higher the weight will be the higher the stall speed and the inertia will be.
Third consideraion : if you are flying up wind (the real plane speed will be plane speed + wind speed) and you make a sudden downwind turn ( the real speed will be plane speed - wind speed) you risk a sudden stall. The problem arises when the difference from flying and stall speeds is lower than 2 times the wind speed.
But this happens with all planes, maybe it is more probable with the light one, but also the heavy ones are not free of this risk.
The only way to avoid stall going from up wind to down wind is to make gentle and large turns, givin time to the plane to increase its speed keepeing its real speed higher than the stall speed.

agree. i wish those who think the downwind turn is not, could read-and assimilate-what you say.

thats why i always do figure 8s facing the wind.

eagle. The planes airspeed does not change with turn. Air speed + plus wind speed = Ground speed. You perceive it different from ground so you fly the plane wrong. Operator error, not due to Downwind Turn Myth (read Unicorn)

If you read my comment and consider "real speed" as air speed and "speed" as ground speed the comment will become more clear. Off course the plane travel in the air at the same speed in stable situation, but you are forgetting the plane inertia : if you make a sudden turn from upwind to downwind the plane will need few seconds to accelerate to the normal flying speed in respect to air (it will have to regain twice the wind speed). As the ground speed is the one essential for inertia in those few seconds the plane in respect of the air could be be slower than the minimum sustainment speed, thus causing stall. That is why it is wise to make large and slow turns in order to give the plane time to accelerate to its normal air speed.
I remember that some years ago a commercial passenger flight was landing into an island nose to the wind and when it was about 30/40 m high it had to face a sudden wind stop. Gess what : it crashed with a lot of victims, so wind is important.