What action should be taken to achieve a positive (plus) moment aft of the datum?

To achieve a positive (plus) moment aft of the datum, adding weight is an effective action. In aviation, the moment refers to the rotational force applied around a specific point, known as the datum. The moment is calculated as the product of the weight and the distance from the datum.

When weight is added to an aircraft, it increases the total moment if added sufficiently away from the datum. For instance, placing an additional load towards the tail of the aircraft will create a moment that acts to rotate the aircraft about the datum in a positive direction, thereby increasing stability and improving control during flight.

In contrast, removing weight, changing the fuel load, or increasing passenger capacity could lead to a negative moment if not managed properly. These actions might either reduce the total moment or redistribute it in a way that does not contribute positively to the desired balance. Therefore, adding weight in a strategic manner is the primary way to increase the moment aft of the datum effectively.