In actual, declaring MOB situation as a distress or an Urgency depends upon a lot of circumstances and sound judgement of the Master. For eg. let us assume a situation where the person has gone overboard but is in sight and rescue operations are initiated. A sound judgement will always tell to transmit such situation as PAN PAN (urgency) as the situation is under control and there is no immediate danger to the life. This is because, once Mayday is transmitted it will ”redirect” all the traffic towards you and all other emergencies would ”lockout” since a Mayday call has already been initiated by the vessel. Let us assume a scenario, where by the MOB’s time and position is unknown. In this case, let us say that the Master evaluates (keeping in mind the situation and circumstances including weather, sea, light, visibility ) and then concludes that he might gain a ”upper hand” if he initiates a Mayday call instead of Urgency. Understand that ”Location” is an extremely important factor in ”Distress” call.So, what i mean to say is that it would depend entirely upon the discretion of Master whether to initiate the call as URGENCY or DISTRESS. If there is an immediate danger to the life, DISTRESS should always be initiated. However, do note that an ”URGENCY” call can be upgraded to ”DISTRESS” situation and NOT vice-versa.
If any doubt exists the ship’s contingency manual should always be consulted and checked for as to which call should be made in order to show compliance with SMS contingency procedures.

In actual, declaring MOB situation as a distress or an Urgency depends upon a lot of circumstances and sound judgement of the Master.
For eg. let us assume a situation where the person has gone overboard but is in sight and rescue operations are initiated. A sound judgement will always tell to transmit such situation as PAN PAN (urgency) as the situation is under control and there is no immediate danger to the life. This is because, once Mayday is transmitted it will ”redirect” all the traffic towards you and all other emergencies would ”lockout” since a Mayday call has already been initiated by the vessel.
Let us assume a scenario, where by the MOB’s time and position is unknown. In this case, let us say that the Master evaluates (keeping in mind the situation and circumstances including weather, sea, light, visibility ) and then concludes that he might gain a ”upper hand” if he initiates a Mayday call instead of Urgency. Understand that ”Location” is an extremely important factor in ”Distress” call.
So, what i mean to say is that it would depend entirely upon the discretion of Master whether to initiate the call as URGENCY or DISTRESS. If there is an immediate danger to the life, DISTRESS should always be initiated. However, do note that an ”URGENCY” call can be upgraded to ”DISTRESS” situation and NOT vice-versa.
If any doubt exists the ship’s contingency manual should always be consulted and checked for as to which call should be made in order to show compliance with SMS contingency procedures.