Flight Performance and Planning (Mass and Balance, Performance)
Core concepts
This domain covers mass and balance and takeoff, climb, landing and cruise performance. Know how to compute the centre of gravity from moments, how to shift CG by moving or adding load, and how mass affects stall speed, takeoff distance, climb rate and landing roll. Understand the variables in performance charts: pressure altitude, temperature, wind, runway slope and surface, and aircraft configuration.
Traps
Common errors: using the wrong datum or arm sign, forgetting to convert mass to weight, ignoring fuel burn's effect on CG during flight, and reading a chart at indicated rather than pressure altitude. Questions often test whether an aircraft is within both mass and CG limits after a last-minute load change. Also watch for density altitude traps: high, hot and humid conditions reduce performance more than temperature alone suggests.
Worked example
Aircraft empty mass 700 kg at arm 2.0 m; pilot 80 kg at 1.5 m; baggage 20 kg at 3.0 m. Moments: 1400 + 120 + 60 = 1580 kg·m; total mass 800 kg; CG = 1580/800 = 1.975 m. If the forward limit is 1.98 m, the aircraft is out of limits forward, and you must move load aft or reduce forward load. Rule of thumb: adding mass aft of the CG moves the CG aft; adding mass forward of it moves it forward, in proportion to moment change.
Exam technique
Show your units, keep a moment table, and check the answer against the envelope sketch before selecting an option.