Flight Performance and Planning (Mass and Balance, Performance)
Flight Performance and Planning
This domain tests mass and balance and aircraft performance: can the aircraft carry the load, is the CG inside limits, and can it take off, climb and land within the available distances?
Mass and balance. Start with basic empty weight and arm, add crew, passengers, baggage, fuel and cargo, and compute moments. Total weight must not exceed MTOW, MLW or MZFW, and the CG must stay between the forward and aft limits for take-off, in-flight and landing. Fuel burn moves the CG because fuel has an arm.
Performance. Use pressure altitude, temperature, wind, runway slope, surface and obstacle data. Density altitude rises with altitude, temperature and humidity, reducing engine power, propeller thrust and lift. Take-off distance increases with tailwind, upslope, soft runways and high density altitude; landing distance increases with tailwind, downslope and contaminated runways.
Worked example
Basic empty weight 800 kg at arm 1.0 m; pilot and passenger 160 kg at 0.5 m; baggage 20 kg at 2.0 m; fuel 100 kg at 1.0 m. Moments: 800 + 80 + 40 + 100 = 1,020 kg·m; weight 1,080 kg; CG = 0.94 m. If the forward limit is 0.95 m, the aircraft is out of balance and baggage must be moved aft or fuel reduced.
Traps
Do not mix kilograms and pounds. Do not use indicated altitude as pressure altitude. Remember that fuel burn can move the CG forward or aft depending on tank location, and never plan to use the final reserve.