What is Urgency and Safety communications ?

Alert is to be transmitted on the DSC distress frequencies. Urgency message normally to be transmitted on RT (Distress), 2182 kHz or NBDP frequency.
Moreover, in case of a long message, a medical call, or in areas of heavy traffic when the message in being repeated, then it is send on a working frequency after an announcement using the urgency signal on an appropriate distress frequency.

What does urgency signal mean:

Urgency signal PAN – PAN indicates that a very important message is to follow concerning the safety of a ship, aircraft or other vechile or the safety of a person.

Urgency Alert :-

In GMDSS urgency indicates that a very important message is to follow concerning the safety of ship, aircraft or other vechile or the safety of a person. Urgency call may be address to All Stations or to an Individual Station.