Module MOD-06 · 8 min · ACS PA.I.F

Weight and Balance Fundamentals

← Weight, Balance and Aircraft Performancedraft — pending CFI review

Why this matters in flight: An airplane loaded outside its limits may be unable to climb, may be uncontrollable, or may exceed its structural strength. Every pilot is legally responsible for confirming the airplane is within weight and CG limits before every flight.
The center-of-gravity envelopeA graph with center of gravity (arm) on the horizontal axis and total weight on the vertical axis. A shaded four-sided envelope marks the approved combinations. A point that falls inside the envelope is within limits; a point outside — too far forward, too far aft, or over maximum gross weight — is unsafe and not authorized.WeightCG (arm) →Max gross weightWITHIN LIMITSFwd limitAft limitLoaded ✓Out of limits ✗
DRAFT schematic — pending CFI review. Illustrative envelope only; always use YOUR aircraft POH/AFM. A loaded weight-and-CG point must fall inside the envelope. Not to scale; not an FAA-approved figure.

Weight and balance rests on a few terms. The empty weight is the airplane with operating fluids but no people, bags, or usable fuel. The useful load is what is left before hitting maximum gross weight — the pilot, passengers, fuel, and baggage. Where each item sits is measured by its arm, the distance in inches from the reference datum, and the product of weight and arm is the moment. To work a loading problem you list every item with its weight and arm, multiply to get each moment, add up the weights, add up the moments, and divide total moment by total weight to find the center of gravity. A loading is legal only if the total weight is at or below the maximum AND the CG falls between the forward and aft limits. Both tests must pass; an airplane can be light but still nose- or tail-heavy. Because fuel burns off during flight and shifts the CG, a loading that is legal at takeoff must remain legal at landing.

Key terms

Empty weight
The airplane with operating fluids but no useful load.
Useful load
Maximum gross weight minus empty weight: people, fuel, and baggage.
Moment
Weight multiplied by arm; a measure of turning tendency about the datum.
Center of gravity
Total moment divided by total weight; the balance point.

Summary

Empty weight plus useful load equals gross weight; CG is total moment over total weight; a loading is legal only when both weight and CG are within limits, including after fuel burn.

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What does the empty weight of an airplane include?

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Sources

Every claim traces to a source — paraphrased knowledge elements pointing at the governing FAA publication; not yet verified against a retrieved source.

  • FAA-H-8083-1 Ch. 1 — Aircraft Weight and Balance Handbook unverified
  • FAA-H-8083-1 Ch. 4 — Aircraft Weight and Balance Handbook unverified
  • FAA-H-8083-1 Ch. 4 — Aircraft Weight and Balance Handbook unverified

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