Originally Posted by
lucky9876coins
Not really an expert in this field, but I don't believe it is an IDB, since you are not being denied boarding, but are just being downgraded.
It may be that it would just be handled through customer relations, but I would think they would seek volunteers to downgrade first.
If you are downgraded NC-->(Y+) on an international flight it seems that you should get more than your miles back. I buy M/H tickets at a ~$400 premium over Q for transpacs only when I can get the upgrade confirmed at purchase time. If months later I lose the upgrade am I due no compensation for purchasing the more expensive ticket? (Assuming the less expensive fare bucket is not available at the time I lose the upgrade)