Weight and Balance (W&B)

Weight and balance (W&B) is the discipline of confirming, before every flight, that the aircraft is below its maximum-allowable weights and that its centre of gravity (CG) lies within the certificated CG envelope at every weight in the operating range. The pilot's responsibility is codified in 14 CFR §91.9 (operating limitations) and §91.103 (preflight action); EASA places it in Part-NCO.OP.180 (general aviation) and Part-CAT.POL.MAB (commercial air transport mass and balance), with the certification basis in CS-23 (normal category), CS-25 (large aeroplanes), CS-27 / CS-29 (rotorcraft).

The weight components are: empty weight (the aircraft as manufactured plus standard equipment, full operating fluids, unusable fuel) — sometimes published as basic empty weight when aircraft-specific options are included; useful load (max gross minus empty); payload (passengers + baggage + cargo); zero fuel weight (ZFW = empty + payload, no usable fuel); ramp / taxi weight (ZFW + fuel including taxi burn); takeoff weight (TOW = ramp − taxi fuel); landing weight (LW = TOW − trip fuel). Each has a certificated maximum: MTOW, MLW, MZFW, MRW. Exceeding any limit is illegal and causes structural-margin compromise plus performance shortfall.

The CG calculation uses the moment method: arm × weight = moment for each loading station; sum of moments divided by total weight gives CG, expressed in inches (FAA) or millimetres (EASA) from the reference datum, then converted to %MAC (mean aerodynamic chord) for transport aircraft. The CG envelope is published in the AFM as a graph or table — forward and aft limits at each weight. Forward CG produces pitch-down tendency, slower stall recovery, and higher landing-approach speed. Aft CG produces longitudinal instability if too far aft; within acceptable range, aft CG yields better cruise efficiency. CG outside envelope is a no-go condition.

For transport-category operations, the load sheet is generated by the operator's load-control system and signed by the dispatcher / FOO before pushback; pilots accept the load sheet as the binding W&B record. For GA, the pilot calculates W&B for each flight using the AFM tables and the actual passenger/baggage/fuel loading. Hot, high, heavy operations push the calculation closer to limits and require more careful runway-required and single-engine-climb verification.

W&B errors are recurring incident causes. Common patterns: passengers re-seating after the load sheet is signed, baggage loaded to a different hold than calculated, last-minute fuel additions pushing TOW over MTOW, uplift errors at an unfamiliar field. For transport-category operators, the load-sheet generation system and the change-of-load procedure are audited under EASA Part-CAT and FAA OpsSpecs.

For flight schools, W&B is a recurring teaching point that students often treat as procedural box-checking rather than safety-critical. A heavy summer cross-country with four occupants and full fuel in a Cessna 172 is right at MTOW with potentially aft-of-limit CG depending on baggage placement — the lesson is best taught with the actual aircraft loaded and the calculation done before engine start. Schools that enforce W&B as a non-skippable preflight item produce graduates who carry the discipline into commercial operations.

Aviatize's smart planning and booking module includes W&B calculation per fleet aircraft. Each booking asks for passenger count, baggage estimate, fuel state, and computes the resulting MTOW and CG state against the published envelope. Bookings that would result in an out-of-envelope condition are flagged before the lesson is confirmed — refusing the obviously-illegal flight rather than discovering the issue at the aircraft.

For instructors, the W&B calculation is captured as part of the lesson plan's preflight section, and the post-lesson debrief can grade the student's W&B competency under the relevant CBTA observable behaviors. The data flows into the student's training record, supporting evidence that the student has demonstrated W&B calculation competency consistently — useful both for stage-check signoff and for downstream airline-employer verification.