Not necessarily unrecoverable but very difficult -
you have two choices - leave the power off and push the stick FORWARD (because the wind is behind you so down elevator with a tailwind may push the tail down). OR:-
Stick back and a burst of power to get the slipstream to "blow" the tail down.
Both of these, especially the second, takes a lot of nerve, plus of course, if you try the second and it does not work, you actually end up doing more damage!