Where do arm measurements begin in an aircraft?

The starting point for arm measurements in an aircraft is at the Reference Datum, typically located at the nose of the aircraft. This reference point is crucial for maintaining accurate weight and balance calculations, which are essential for safe flight operations.

The arms are measured as the horizontal distance from the Reference Datum to the center of gravity of various components of the aircraft, such as the payload and fuel. By establishing this standardized starting point, pilots and weight and balance personnel can ensure consistency and accuracy in their calculations.

Understanding this concept is vital for any aviation professional, as precise arm measurements directly impact the aircraft's performance, stability, and overall aerodynamics during flight.