Flight Operations, Performance and Weight and Balance
What the paper tests
This domain tests the flight engineer's practical arithmetic: take-off and landing performance (V speeds, runway length, contamination, density altitude), the mass limitations MTOW, MLW and MZFW, fuel planning, and centre of gravity control through the load sheet.
Core rules
- Take-off mass is the lowest of the structural, performance-limited and regulated values; each must be checked, not just the structural one.
- Performance degrades steeply with density altitude, tailwind and runway contamination; a 10 kt tailwind can raise take-off distance by roughly a fifth.
- CG must stay inside the certified forward and aft limits at take-off, in flight (allowing for fuel burn) and at landing.
- The load sheet must reconcile: basic empty mass plus traffic load plus fuel equals take-off mass.
Worked example
Basic empty mass 40,000 kg at 18.5 m; traffic load 12,000 kg at 22.0 m; fuel 9,000 kg at 25.0 m. Moments: 740,000 + 264,000 + 225,000 = 1,229,000 kg·m. Total mass = 61,000 kg. CG = 1,229,000 ÷ 61,000 = 20.15 m, inside a 17.5–24.0 m envelope. Check MZFW too: 40,000 + 12,000 = 52,000 kg must not exceed the certified MZFW.
Traps
Mixing kilograms and pounds, forgetting that fuel burns off and moves the CG aft, omitting the MZFW check, and copying index units from a load sheet without converting to a CG arm.