We have a couple of threads talking about this topic and I have posted a lot of technique in them. This is a very common issue and it is the result of a combination of factors. Number one of which is stiff legs and leaning back over the heel edge. The steeper the terrain the lower you need to be. Squat into the heelside turn and really flex the ankles to keep your body over the board not way out over the heel edge.
Another issue is too much acceleration through turn entry so that when the board moves through the bottom of the turn, there is too much force generated to maintain edge hold. Working the top of the turn and setting the the new edge earlier in the turn is crucial for speed control through your turn.
To ride steeps with any success, you need to ride very dynamically and at 7 times riding, the reality is you are not there yet. It takes time to progress into dynamic skidded turns, basic carved turns and dynamic carved turns. Start you progression into dynamic riding by focusing on keeping your body in motion at all times and never getting static on the board. The key to this is flexing and extending constantly and timing these movements so that they correctly coincide with the phase of each turn you are in.
Right now, I want you to start practicing getting as low as you possibly can when the board is across the fall line and making your edge change before the board dives down into the fall line. As soon as the turn is established, slowly extend up through the turn to increase edge pressure. Do this all the way through the apex of turn; you should be most extended at apex and most flexed as the crosses the fall line. As the board passes through the apex of the turn and you are steering it back out of the fall line across the hill, slowly begin to flex again and if heelside, squat into more and more as is drives through the bottom of the turn.
Later on, fore-aft movements will need to be added to increase effectiveness but at your stage of riding, focus on learning each new task one at a time. Really focus on flexion/extension.
Now, when you come out of the bottom of your turn , if you feel the chatter start, imediately loosen up even more. The natural reaction is to stiffen up and push the edge harder. The reason the chatter is happening is because you are loosing edge hold. Pushing against it now will only cause the edge to totally blow out and skid out of control to the outside of the turn. Anytime shit starts to go wrong snowboarding, bend something!
Give this a try and let us know how it felt and what the difference was regarding board performance.
This. All of it.
I was up in Seattle and I kept washing out heel side on steeps and at speed. It's actually a problem I've had going back a few seasons if I'm not almost bombing the run straight down. Could never figure it out (toe side was no problemo) until I read a few threads in here.
You can do just put your ass into it
Seriously, I just squatted as far as I needed to until the board stopped chattering and skipping the snow. I always had a problem carving heel side and this solved it. It's amazing what a little technique change does for you.