Re: Mayday or not to mayday?
The decision whether to declare a Mayday or a Pan surely relates to the ICAO definitions of distress and urgency, namely:
a) Distress: a condition of being threatened by serious and/or imminent danger and of requiring immediate assistance.
b) Urgency: a condition concerning the safety of an aircraft or other vehicle, or of some person on board or within sight, but which does not require immediate assistance.
If it is the captain's judgement that he is in serious and imminent danger, he should transmit a Mayday call - QED.
Mel