Thanks for all the replies guys. I'm glad the thread started. To summarise, with ELAC 2 not available, in the event of a loss of the blue system through either system failure (e.g rupture) or loss of AC power, elevator control is lost until the blue system is powered again. ELAC 1 will not transfer control to SEC 2 unless it has failed electrically, even though SEC 2 always remains powered (through its associated HOT BUS) and in control of the L and R elevator through the B and G systems, it just can't "use" that authority because ELAC 1 still "has control" even though it has no way of asserting that control. Seems like a line of code could be written to tell ELAC 1 to surrender control in that situation but with feedback, it would probably take a few seconds to restructure the control path and Airbus get around it by simply making ELAC 2 the no -go.