In the USA airport facilities directory (AFD), some towers (eg KSJC) are listed with the note:
Emerg frequency 121.5 not avbl at tower.
Why do these facilities not monitor guard? Does the note actually mean that they cannot even talk on 121.5 in an emergency?
I am assuming it is because a different facility in the area (eg a TRACON) is monitoring guard, and they don’t want two facilities taking responsibility for guard. But suppose an airplane is landing in an emergency, does that mean the tower couldn’t even listen to the emergency communications?
How does this work practically in emergencies?