Flight Performance and Planning - Performance, Mass & Balance, Fuel
Performance
Take-off and landing distances come from the aeroplane flight manual and must be corrected for mass, pressure altitude, temperature, wind, runway slope and surface, and flap setting. Density altitude is the central concept: it combines elevation and temperature, and both high elevation and high temperature increase it, lengthening the ground roll and reducing the climb gradient. Climb performance also degrades with mass, altitude and temperature.
Mass and balance
Every loading problem reduces to moment ÷ mass = centre-of-gravity position. Start with the empty mass and moment from the manual, add crew, fuel, baggage and payload moments, then check the result lies inside the CG envelope for the take-off and landing configurations. An aft CG reduces stability and stick force; a forward CG increases stick force and can reduce elevator authority, lengthening the take-off run.
Fuel
Plan taxi, trip, contingency and final reserve fuel, and be able to convert a reserve expressed in time into litres using the hourly consumption. Re-check fuel and groundspeed at each waypoint rather than waiting for the destination.
Common traps
Using true instead of indicated airspeed in the charts; forgetting that a tailwind lengthens take-off and landing distances; mixing imperial and metric units; and applying a wind correction in the wrong direction.
Worked example
Runway 09, wind 060° at 20 kt. The angle is 30°, so the crosswind component is 20 × sin 30° = 10 kt and the headwind is 20 × cos 30° = 17 kt. Against a 15 kt crosswind limit you are legal, and the headwind may be entered as a favourable correction on the take-off chart.