Where is the datum in weight and balance measurements?

Where is the datum in weight and balance measurements?

• A. A fixed reference point from which arms are measured
• B. The aircraft's center of gravity
• C. The tail section
• D. The wing root

Answer: (A)

In weight and balance, a fixed reference point called the datum is used to measure the distance (arms) to where weights are located. Every weight’s arm is the distance from that datum to the point where the weight sits, and the moment for each weight is found by multiplying the weight by its arm. The datum is defined by the manufacturer and stays at a fixed position on the airframe; the center of gravity is the actual balance point that results from loading, not the reference point itself. The tail section or wing root are physical parts of the airplane, not the reference point used for weight-and-balance measurements.

In weight and balance, a fixed reference point called the datum is used to measure the distance (arms) to where weights are located. Every weight’s arm is the distance from that datum to the point where the weight sits, and the moment for each weight is found by multiplying the weight by its arm. The datum is defined by the manufacturer and stays at a fixed position on the airframe; the center of gravity is the actual balance point that results from loading, not the reference point itself. The tail section or wing root are physical parts of the airplane, not the reference point used for weight-and-balance measurements.