That rust looks like old and deep pitting. That is hard to get out, that stuff keeps coming back whatever you do.
You might try some Rust Converter liquid on that plane, then sand back to a nice finish. The pits will hold the rust converter and inhibit future rust.
Also, following on from the great points made by the last poster, I have gone through a process to get my wet and damp garage converted into a reasonably okay space, I still get rust but it’s way less than before.
Let me know if you want me to post an overview of what I did.