Understanding Aircraft Center of Gravity

Calculating the Center of Gravity (CG) is a critical component of pre-flight planning for every pilot. The CG is the specific point over which the aircraft would balance if suspended in the air. For an aircraft to fly safely and predictably, its weight must be distributed within specific limits defined by the manufacturer. If an aircraft is loaded outside of its CG envelope, it can lead to catastrophic loss of control.

How to Use This Calculator

To use this Aircraft CG Calculator, you need the weight and arm values for your specific aircraft. The "Arm" is the horizontal distance from a reference datum (often the firewall or the nose of the plane) to the item's center of gravity.

1. Enter the Basic Empty Weight (BEW) and its Arm from your aircraft's latest weight and balance sheet.
2. Input the weight of the pilot and passengers along with their respective seat arms.
3. Add the fuel weight (typically 6 lbs per gallon for AvGas) and the arm of the fuel tanks.
4. Enter any baggage weight and its location arm.
5. Click calculate to see your total weight and the final CG position.

Why Weight and Balance Matters

Loading an aircraft too far forward (Forward CG) increases stability but requires more elevator authority to lift the nose, which can make landing difficult or impossible. Conversely, loading an aircraft too far aft (Aft CG) reduces stability and can make the aircraft impossible to recover from a stall or spin. Additionally, exceeding the Maximum Takeoff Weight (MTOW) increases takeoff distance and reduces climb performance and structural safety margins.

Frequently Asked Questions

What is the Reference Datum?

The reference datum is an imaginary vertical plane from which all horizontal distances are measured for balance purposes. It is established by the manufacturer and can be found in the Pilot's Operating Handbook (POH).

How does fuel burn affect CG?

As fuel is consumed during flight, the total weight of the aircraft decreases and the CG often shifts. Pilots must ensure the aircraft remains within CG limits both at takeoff and with empty tanks upon landing.

Can I use this for any aircraft?

While the physics of weight * arm = moment applies to all aircraft, always verify the resulting data against your specific POH and official weight and balance records for your tail number.