How about a "Forced Radio Silence" function?
For instance, a mission starts, everyone is chatting and talking as usual. But the leader of the mission, when he feels there's something important to address to the entire flight, he pushes the "forced radio silence" button - which will block out all vox transmissions and receptions. Only the leader will speak, and what he speaks is the only thing the entire flight will hear.
Maybe it's a too powerful function, but I don't think people will come to abuse it too much - I'd imagine people will just drop out from the mission and go by their own business if the mission leader abuses it too much. If someone wants to do a mission, then he'd better not be a dick.
