If you called Pan-Pan in the US most folks wouldn't have a clue what you were talking about
Perhaps they should read US Aeronautical Information Manual 6-3-1(c)......"The initial communication, and if considered necessary, any subsequent transmissions by an aircraft in distress should begin with the word MAYDAY, preferably repeated three times. The signal PAN-PAN should be used in the same manner for an urgency condition".
Airclues