Flight Performance and Planning
Performance fundamentals
Performance questions test your ability to use take-off, landing, climb, and cruise data correctly. Know the definitions: take-off distance available (TODA), take-off run available (TORA), accelerate-stop distance available (ASDA), and landing distance available (LDA). Understand the difference between ground roll and the distance to 50 ft, and why obstacle clearance is built into the take-off flight path.
Mass and balance
Know that centre of gravity affects stability and control: too far forward increases stick forces and stall speed; too far aft reduces stability and can make recovery from a stall difficult. Compute moments as mass × arm, and remember that adding mass at a given station shifts the CG toward that station.
Planning
Fuel planning must include taxi, trip, contingency, alternate, and final reserve. Know that density altitude raises take-off and landing distances, and that headwind and tailwind affect them significantly.
Traps
- Using TORA when the question asks for TODA.
- Forgetting to correct for density altitude when the question gives pressure altitude and temperature.
- Mixing mass and weight units, or forgetting to convert.
- Assuming a tailwind improves performance; it degrades it.
Worked example
A 10 % increase in take-off mass increases the stall speed by about 5 % (square root relationship) and the take-off distance by roughly 20 % or more. Apply the square-root rule for speed and the squared rule for distance when estimating.