Originally Posted by 737jock
As you see from the requirements vmca is determined at the maximum sea-level take-off weight.
You are misreading the requirements. Even though Vmca varies little with weight, it is usually determined at all weights where it may be limiting V2, which is usually at the low end of the take-off weight range. It may optionally be determined at the minimum take-of weight because Vmca decreases with increasing weight if a 5 degree bank is used.
JAR/FAR 25.149(c)(4) states an additional requirement, i.e. that Vmca may not exceed 1.13 Vsr at the Vsr for maximum sea-level take-off weight (or any lesser weight necessary to show Vmc).