OK guys,
Now I'm back on the ground, further info to my apparently shocking statement that Vmca can be and in fact is below Vs1g on big Boeings by a good margin.
Assuming 380T and close to sea level standard conditions, Mr Boeing assures me, via his certified Performance Limitations Manuals, "observance of which is required by law", that for RR Vs1g clean is 205Kts and Vmca is 117Kts while for GE Vs1g clean is also 205Kts and Vmca is 120Kts.
You quote, vilas, that Vmca may not exceed 1.2Vs but that does NOT mean that it cannot be lower, in fact it infers a lower speed.
How Vmca is determined when it is below Vs1g is beyond me - I'm just a pilot, not a designer.