Chattering on the bottom 1/3 of the turn, particularly on steeper and icier surfaces, might one of the most common struggles seen on the slopes. The primary reason for chatter is because you are not carving, you are trying to skid. If you init your turns cleanly on a bent ski and get it to glide more, chatter will be reduced or eliminated.
But what happens is that if you create some steering angle, because you want to skid and slow yourself down. In the bottom half of the turn, the forces all conspire against you because you are trying to edge enough to slow yourself down, but your edges want to bounce out of their slots down the hill due to the force of gravity and turn forces combining there.
You can flatten your ski, but then your tails are likely going to wash out too.
so what then? For starters, get forward onto the shovels from the very top of the turn and stay forward, don't fall back onto the tails. Keep the ski bent!! You want to make something closer to a carved turn. You want to slow yourself down with line choice rather than skidding and especially without your heels pushing out.