Flight Performance and Planning: Mass, Balance and Performance
Mass and balance
Every performance calculation begins with mass and centre of gravity. Know the terms: basic empty mass, dry operating mass, take-off mass, landing mass, zero-fuel mass, and maximum structural limits for each. Centre of gravity must remain within the forward and aft limits for the whole flight, including fuel burn and load shifts. A forward CG increases stability but raises stall speed and elevator forces; an aft CG reduces stability and can make stall recovery difficult.
Performance
Performance questions test the relationship between density altitude, mass, wind, runway slope and surface, and the resulting take-off and landing distances. High, hot and heavy means longer distances. Know how to use the aircraft flight manual charts and how to apply corrections - the trap is applying corrections in the wrong order or forgetting to convert indicated to true airspeed, or pressure altitude to density altitude. Another trap is confusing accelerate-stop with accelerate-go concepts, and misreading whether a chart gives ground roll or total distance to 50 ft.
Worked example / rule of thumb
Rule of thumb: a 10 °C rise in temperature or a 1000 ft increase in pressure altitude increases take-off distance by roughly 10 % each; a 10 % mass increase raises take-off distance by about 20 %. For balance, always compute the moment (mass × arm) and divide total moment by total mass to find the CG; if the result falls outside limits, move load before considering ballast.
Study strategy
Practise one full load sheet and one take-off chart from start to finish, writing each step, until the sequence is automatic.