What does the term "arm" refer to in aviation?

In aviation, the term "arm" specifically refers to the distance measured from the aircraft's center of gravity (CG) to a reference datum point. This measurement is crucial for determining weight and balance, as the CG affects the aircraft's stability and control during flight. The arm is typically expressed in inches or centimeters and is used when calculating moments, which help to ensure that the weight distribution is appropriate for safe flight.

Understanding the arm is essential for pilots and engineers when preparing the aircraft for flight, as improper loading or balance can lead to difficult flying conditions or even accidents. Properly calculating the arm helps ensure that the aircraft operates within its performance limits, maintaining safety and efficiency.