Flight Performance and Planning
Performance and planning questions test your ability to compute and to sanity-check. Know the take-off and landing distance factors: mass, density altitude, wind, runway slope and surface. Understand that take-off distance increases with mass, altitude, temperature and tailwind, and decreases with headwind and downhill slope. Learn to use the aircraft flight manual charts and to apply the safety factors required by regulation. For planning, know fuel computation (trip, reserve, contingency, taxi), mass and balance (empty mass, payload, fuel, CG position), and the effect of loading on performance.
Traps: forgetting to convert units (litres to kilograms using fuel density, feet to metres), using the wrong chart axis, and ignoring the effect of a tailwind on landing distance. Candidates also miscompute mass and balance by forgetting that fuel burn moves the CG. Always check that the planned mass and CG fall within the envelope, not just within maximum mass.
Worked example: cruise fuel 60 L, reserve 30 min at 30 L/h = 15 L, taxi 3 L, contingency 5 L. Total = 60 + 15 + 3 + 5 = 83 L. If fuel density is 0.72 kg/L, that is about 60 kg. Rule of thumb: a 10 kt tailwind increases take-off and landing distance by roughly 20%; a 10% increase in mass increases take-off distance by about 20%. Always add a personal margin and verify the CG after fuel burn.