As you see from the requirements vmca is determined at the maximum sea-level take-off weight.
What do you mean with: he is comparing the stallspeed at that weight to the minimum control speed established at a lesser weight extrapolated to the actual weight?
An aircraft will also stall at full-power, so why do you want to compare vmca at full power with a stallspeed without power?
The entire point of VMCA is to demonstrate the ability to maintain direction (even though you heading can still change up to 20 degrees) after becoming airborne with the most critical engine failed, the other engine(s) at max to power and a bank maximum bank of 5 degrees.
And thats about as far as VMCA goes. Sure you can demonstrate that in the clean configuration at FL200 you can put TOGA on one engine and then stall it, but thats not the definition of VMCA as required by FAR/JAR. It would be another variant of VMC, like for example VMCL.
just my 2 cents
I realise how you can theoretically, and even practically if it wasn't for the ground being so damn close, get a lower VMC then stallspeed. For me it just has very little to do with the VMCA requirements.
Last edited by 737Jock; 13th Apr 2014 at 15:45.