In terms of weight and balance, what must be calculated if weight is removed from the aircraft?

The correct choice involves calculating the moment relative to the datum when weight is removed from the aircraft. This is essential because the moment is the product of weight and its arm (the distance from the datum to the center of gravity). Understanding how removing weight affects the moment helps to maintain the aircraft's balance and ensures that the center of gravity remains within the acceptable limits for safe operation.

When weight is removed, it not only reduces the overall weight but also alters the distribution of that weight across the aircraft. This shift can affect how the aircraft performs during flight, including stability and control. Therefore, it is essential to calculate the new moment to determine how the aircraft's center of gravity has shifted and whether it still falls within the safe operating parameters.

While fuel levels, maximum takeoff weight, and the actual weight are important factors in overall weight and balance considerations, the moment relative to the datum specifically accounts for how changing weight impacts the aircraft's balance directly. This is why understanding and calculating the moment is crucial in weight and balance assessments after any weight change.