As in waterspace management, there is airspace management for MPA. Of course if neither submarine or MPA are in assigned spaces, normal rules apply.
One day an SSN was transiting on the surface East of Scotland. Every oil rig helicopter called it in on common and every Nimrod in the area homed in. As one helo called in, you look like bees round a honey pot as 3 Nimrods took turns. I think our dark blue friend was not happy.