There are no "backbenchers" or "government" in the US, just the majority and minority parties. Both the sponsors of this bill are Democrats. Of course the airlines will oppose this, the question is how strongly.

The vast majority of bills that are introduced never get beyond the committee stage, usually because there is no one pushing them. If a well-funded interest group takes on the challenge, it may get through and be brought to a floor vote. At that point, I would expect most Republicans to oppose it, along with Democrats who are not progressives.

So while it's hard to predict, I would say this bill's odds of being passed are very low.