Mass and Balance Documentation: Required Content and Compliance Use

031-04-01Pablo Asensio Martínez2026-04-011 min

Required Documentation

Every aircraft must have a Mass and Balance Manual (or section in the Flight Manual/POH) approved by the authority. This document contains:

  1. Datum Definition: The reference line from which all longitudinal distances (arms) are measured.
  2. CG Envelope: A graph or table showing the allowable range of CG positions for various masses.
  3. Maximum Mass Limits: MTOM, MLM, MZFM.
  4. Weighing Report: The most recent weighing data, establishing the aircraft's Basic Empty Mass (BEM) and its CG position.
  5. Equipment List: A list of installed equipment included in the BEM.

CG Envelope

The allowable CG range typically changes with mass. The documentation provides a CG Envelope diagram with:

  • X-axis: Centre of Gravity location (inches, meters, or % MAC).
  • Y-axis: Aircraft Mass (kg or lbs).

The pilot must verify that the calculated mass and CG for the flight fall within the boundaries of this envelope.

Weighing Schedule

Commercial aircraft must be re-weighed periodically:

  • Individual Aircraft: Every 4 years.
  • Fleet Mass: If using fleet values, sampling weighing is required.
  • Modifications: After major modifications or repairs that significantly affect mass or CG.