Flight Performance and Planning
Core concepts
Performance and planning questions require you to compute take-off and landing distances, climb gradients, fuel requirements, mass and balance, and to interpret the aircraft flight manual. Understand density altitude, the effect of mass, wind, and runway slope on performance, and the difference between the take-off distance available (TODA), take-off run available (TORA), and clearway/stopway. For mass and balance, know that the centre of gravity must remain within limits throughout the flight, and that fuel burn shifts the CG.
Traps to watch
Examiners love density altitude: high altitude, high temperature, and high humidity all increase density altitude and degrade performance. Watch for questions mixing pressure altitude with density altitude. In fuel planning, distinguish trip fuel, contingency, alternate, final reserve, and taxi fuel. In mass and balance, remember that adding mass aft of the CG moves it rearward, and that maximum take-off mass is a structural limit, not a performance one. Always check units: litres vs kilograms vs pounds.
Worked example
Aircraft at 5,000 ft pressure altitude, +20 °C. Using a rule of thumb, density altitude rises roughly 120 ft per °C above ISA. ISA at 5,000 ft is about +5 °C, so 15 °C above ISA adds ~1,800 ft, giving a density altitude near 6,800 ft - a significant performance penalty.
Rule of thumb
Hot, high, humid, heavy = worst performance. Convert everything to the same units before computing.