Flight Performance
Performance fundamentals
Performance questions test your ability to read takeoff/landing distance charts, climb performance, cruise tables, and POH graphs correctly. You must understand density altitude, headwind/tailwind correction, runway slope, and obstacle clearance.
Key concepts
- Density altitude: pressure altitude corrected for non-standard temperature. High, hot, humid → poor performance.
- Takeoff distance: ground roll + 50 ft obstacle clearance; affected by weight, wind, slope, surface, and density altitude.
- Landing distance: ground roll + 50 ft; affected by weight, wind, slope, braking action.
- Climb gradient vs rate of climb: gradient is height gained per unit horizontal distance; rate is per unit time.
- Accelerate-stop and accelerate-go concepts for multi-engine (though PCA is single-engine focused, definitions appear).
Traps
- Applying wind correction in the wrong direction (tailwind always hurts; headwind helps).
- Forgetting that chart interpolation must be monotonic - do not mix units.
- Confusing pressure altitude with density altitude in the chart entry.
- Using still-air figures and then adding wind correction in reverse.
Worked example / rule of thumb
If a chart gives takeoff ground roll 500 m at sea level ISA and you must correct for 10 kt headwind, typical POH charts give ~10 % reduction per 9 kt headwind. Rule of thumb: 1 % runway distance per 1 % weight change; 10 % per 1 000 ft density altitude (approximate, verify with POH).
Always apply corrections in the order the POH chart specifies.