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This glossary is written for virtual airline and flight simulation use within Virtual Air Canada Airline. It is not intended as a real-world aviation reference.
Center of Gravity (CG) is the point through which the total weight of an aircraft acts, representing the balance point of the aircraft mass in the longitudinal (fore-aft) axis. CG position is expressed as a percentage of the Mean Aerodynamic Chord (MAC) - the reference chord of the wing - or as a distance from a fixed datum point. For safe flight, the CG must remain within the forward and aft limits defined in the aircraft’s flight manual throughout all phases of flight, from takeoff to landing, including as fuel burns off and the weight distribution shifts. A forward CG requires more nose-up elevator trim to maintain level flight, increasing drag and fuel burn but generally improving pitch stability. An aft CG reduces the stability margin - in extreme cases to the point where the aircraft becomes uncontrollable - but slightly reduces trim drag. CG shifts during flight due to fuel burn from wing and center tanks; airlines carefully plan fuel burn sequences to ensure the CG stays within limits throughout the flight. Weight and balance calculations, including CG determination, are performed by load control using a load sheet before each departure, and the resulting trim setting is provided to the crew for cross-check.

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In Virtual Airline Operations

At Virtual Air Canada Airline, the SimBrief OFP and aircraft-specific load sheets provide CG and trim information that should be entered into the FMS or trim system before departure. In most add-on aircraft, the weight and balance page in the CDU or EFB will display the computed CG and allow verification against limits. Ensuring the CG is set correctly before departure produces accurate takeoff performance calculations and a realistic trim feel during the initial climb.
  • CDU - Control Display Unit
  • CI - Cost Index
  • AFM - Aircraft Flight Manual