FAA Airline Transport Pilot (ATM)Aircraft Performance and Weight and BalanceMedium
An aircraft's leading edge of the mean aerodynamic chord (LEMAC) is located at fuselage station 400.0, and the MAC length is 200 inches. If the loaded CG is calculated to be at station 460.0, what is the CG location expressed as a percentage of MAC (%MAC)?
- A35% MAC
- B30% MAC
- C25% MAC
- D20% MAC
Show answer & explanationAnswer & explanation
Correct answer: B. 30% MAC
%MAC = [(CG station − LEMAC)/MAC length] × 100 = [(460.0 − 400.0)/200] × 100 = (60/200) × 100 = 30%.
Why the other options are wrong
- A. This would require a CG station of 470.0, not 460.0.
- C. This would require a CG station of 450.0, not 460.0.
- D. This would require a CG station of 440.0, not 460.0.
%MAC Calculation
CG position expressed as a percentage of the mean aerodynamic chord, measured from the leading edge of MAC (LEMAC).
- %MAC = (CG station − LEMAC)/MAC length × 100
- Used to check CG against certified forward/aft limits
- MAC length and LEMAC vary by aircraft type
Memory trick: Subtract LEMAC, divide by chord, multiply by 100 — that's your %MAC score.