wrote in message news:
The UK R/T Manual states the following:

States of Emergency are classified as follows:

Distress: A condition of being threatened by serious and/or imminetn
danger and requiring immediate assistance.

Urgency: A condition concerning the safety of an aircraft or other
vehicle, or of some person on board or within sight, but does not
require immediate assistance.

The pilot should make the appropriate emergency call as follows:
Distress: 'Mayday, Mayday, Mayday'
Urgency: 'Pan. Pan, Pan'.

Whatever. What pilots actually do is of far more interest. This is thin
edge of the wedge stuff. And, by definition, emergency situations may
require that some rules be broken. Only an idiot wants to be part of that
club. But, idiots and geniuses alike experience it and I've yet to see one
who frets over the minutiae of distress call protocol.

moo