Originally Posted by
sonicbum
You cannot -from a regulations perspective- deviate from a cleared routing (SID in this case) unless You coordinate an alternative routing (eg. wx avoidance headings or rerouting) or declare at the very least a state of urgency or distress. You are confusing the authority of the PIC which is always to act in the interest of safety even if this goes against rules and regulations with compliance with said rules and regulations.
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So then you do agree that a PAN call would more than cover you legally when you deviate from the SID?
The main thing is that you communicate your intentions clearly, I think we all agree on that. Simply calling mayday will just illicit more distracting questions from ATC. Give them something to work with, enough so they can formulate their own plan, and to give them (and all the other traffic around you) a sense of your level of immediate danger.
Also think of the bigger picture. Calling MAYDAY during the initial confusion of an engine failure? Absolutely. Causing mass diversion whilst you are subsequently in the EOSID hold briefing the minutiae of your single engine ILS, still on a MAYDAY, well…subject for discussion!