HANDBOOK

Important: the radio watch and contact with the vessel in distress
should continue until all activity has ended. A distress or urgency call
can be cancelled by transmitting a message advising that assistance
is no longer required. After that time, a normal listening watch should
be maintained.
When circumstances change, a vessel that has broadcast a MAYDAY
may change the message to a PAN PAN when grave and imminent
danger has passed. A PAN PAN can also be upgraded to a MAYDAY
if a situation deteriorates.
Urgency signal and message
The radio-telephone urgency signal is PAN PAN (spoken three times)
and indicates that the calling station has a very urgent message to
transmit about the safety or operational capability of a vessel, or about
a person in difficulty. Medical emergencies are normally designated as
PAN PAN messages.
The urgency signal has priority over all other communications except
distress. All stations hearing it must take care not to interfere with the
transmission of the message that follows.
The urgency message may be addressed either to ALL STATIONS
or to an INDIVIDUAL STATION. As soon as the station responsible
for transmitting the urgency message knows that action is no longer
necessary, it must cancel the message.
The urgency signal and message should be sent on any international
distress frequency or channel for radio-telephone. In the case of a long
message or medical call, the caller should change to a working frequency.
RADIO HANDBOOK
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