Pilots do train for communication failures. ATC at most airports has a number you can call to be patched through if your radio stops working and I've heard mult

Pilots do train for communication failures. ATC at most airports has a number you can call to be patched through if your radio stops working and I've heard multiple cases of people having to use it. In the worst case, there are non-verbal methods of communication that pilots or ATC can employ (ATC can send light signals, pilots rock their wings to signal communication failures, etc.)