Performance - Aeroplanes
The Performance - Aeroplanes domain tests your ability to use the AFM/POH to predict take-off and landing distance, climb performance and limiting speeds, and to decide whether a runway, obstacle and mass combination is legal. Questions often combine declared distances, density altitude and chart corrections.
Declared distances and speeds
- TORA: take-off run available.
- TODA: TORA plus clearway; ASDA: TORA plus stopway.
- LDA: landing distance available.
- V1 decision speed; VR rotation; V2 take-off safety speed; Vref landing reference speed.
- Vx best angle of climb; Vy best rate. Climb gradient is performance-limited by mass, altitude, temperature and configuration.
Worked example
Pressure altitude 4,000 ft, OAT 25°C. ISA temperature at 4,000 ft is about 7°C, so the excess is 18°C. Using the approximation of 120 ft per °C above ISA, density altitude ≈ 4,000 + (18 × 120) = 6,160 ft. The chart at 6,000 ft, 1,200 kg, zero wind gives a ground roll of 650 m. Grass adds 15%: 748 m. A 5 kt tailwind adds 10%: 823 m. A 1% uphill slope adds 10%: 905 m. This is below TODA 1,100 m, but you must still confirm the obstacle clearance and the required climb gradient.
Traps
Using pressure altitude instead of density altitude; applying correction percentages to the wrong base; forgetting that a clearway may be used for take-off distance but not for the ground run; mixing TORA with TODA; and accepting a runway length that satisfies distance but not climb or obstacle limits. Always interpolate charts and state the units.