Aircraft Performance, Mass and Balance, and Take-off/Landing Data
Core concepts
Performance planning determines whether the aircraft can safely take off and land given runway length, slope, surface, wind, temperature, pressure altitude, and obstacles. Key terms: take-off distance available (TODA), take-off run available (TORA), accelerate-stop distance available (ASDA), landing distance available (LDA). Mass and balance requires computing the centre of gravity (CG) from the basic empty mass, payload, and fuel, and verifying it lies within the forward and aft limits.
Traps
Questions test: using pressure altitude instead of elevation; forgetting temperature correction (density altitude); confusing TORA with TODA (clearway); applying wind correction incorrectly (headwind reduces distance, tailwind increases it); and ignoring the fact that CG moves as fuel burns. Also watch for landing distance being the unfactored distance versus the required factored distance (typically ×1.67 for dry runways).
Worked example / rule of thumb
Rule of thumb: density altitude increases ~120 ft per 1°C above ISA. Example: elevation 1,000 ft, QNH 1013, temp 25°C (ISA 15°C) → ISA deviation +10°C → density altitude ≈ 1,000 + 1,200 = 2,200 ft. Use this to enter the performance chart. For mass: moment = mass × arm; total moment ÷ total mass = CG. Verify CG within limits for take-off, zero-fuel, and landing configurations.