Aircraft Performance
Take-off, climb, cruise and landing
Candidates must understand the take-off run and the factors affecting it: density altitude, weight, wind, runway slope and flap setting. Higher density altitude reduces thrust and lift, lengthening the ground roll. Know the climb performance relationships: rate of climb depends on excess power, and climb gradient on excess thrust per unit weight. Understand V_X (best angle) and V_Y (best rate), and that V_X is lower than V_Y. In cruise, know the relationship between power required and speed, and that maximum endurance occurs at minimum power required while maximum range occurs at a higher speed where the lift-to-drag ratio is greatest.
Traps
Typical traps include assuming V_X and V_Y are the same, forgetting that headwind improves both take-off and landing performance, and confusing endurance with range. Another trap is applying indicated airspeed values without correcting for density altitude, and misreading a climb-gradient versus rate-of-climb question.
Worked example
Aircraft climbs 600 ft in 2 minutes: rate of climb = 300 ft/min. If groundspeed is 90 kt, gradient = (300 ft/min) ÷ (90 kt × 101.3 ft/min per knot) ≈ 3.3%. Rule of thumb: gradient (%) ≈ (rate of climb in ft/min) ÷ (groundspeed in kt) × 0.99, so approximately rate ÷ speed.