Flight Performance and Planning
Flight Performance and Planning tests whether you can use POH data, weight and balance, and fuel rules to produce a legal, safe flight plan.
Performance
Takeoff and landing distances come from the POH and are based on pressure altitude, temperature, weight, wind, runway slope and surface. Density altitude is pressure altitude corrected for temperature; high density altitude reduces power and lift and increases true airspeed for the same IAS. Obstacle clearance must be added, not assumed. Climb performance is quoted for specific weights and configurations.
Weight and balance
Compute total weight and total moment; CG = total moment / total weight. Stay inside both maximum weight and the CG envelope. Fuel density matters: 100LL is about 0.72 kg/L, so 100 L is 72 kg, not 100 kg. Use the actual arm for each station and check the forward and aft limits at the planned zero-fuel and landing weights.
Fuel
Plan taxi, trip, contingency, alternate and final reserve. For VFR, a common planning reserve is 30 minutes; night or isolated operations may require more. Compare planned fuel with usable fuel, not tank capacity.
Worked example
Empty aircraft: 700 kg at moment 700 kg·m. Pilot 80 kg at 0.4 m = 32; passenger 70 kg at 0.4 m = 28; baggage 20 kg at 2.0 m = 40; fuel 100 L = 72 kg at 1.5 m = 108. Total weight 942 kg; total moment 908 kg·m; CG = 0.964 m. If the envelope is 0.85-1.15 m, the loading is legal. Show the moment arithmetic, not just the final CG.
Traps
Using IAS for groundspeed, forgetting temperature correction, treating litres as kilograms, and checking CG only at takeoff. A forward CG can make rotation and flare difficult; an aft CG reduces stability.