Flight Performance, Planning and Loading
Core concepts
Performance questions test take-off and landing distances, climb performance, density altitude, weight and balance, and load sheet interpretation. Understand the effect of mass, altitude, temperature, wind, runway slope and surface on performance. Know centre of gravity limits and how loading affects stability and control.
Traps
- Density altitude is the key hidden variable: high altitude, high temperature and high humidity all reduce performance. Questions often give pressure altitude and temperature and expect you to apply the density altitude effect.
- Headwind vs tailwind: a tailwind increases both take-off and landing distance significantly; never assume symmetric effects.
- Weight and balance: moment = weight × arm; total moment divided by total weight gives CG position. A common error is forgetting to include the empty aircraft's basic mass and moment.
- Runway slope: uphill reduces take-off acceleration but shortens landing roll; downhill the reverse.
Worked example
Basic empty mass 700 kg at arm 2.0 m (moment 1400). Pilot 80 kg at 1.5 m (120), fuel 100 kg at 2.2 m (220). Total mass = 880 kg; total moment = 1740; CG = 1740/880 ≈ 1.98 m. Check against the envelope before accepting.
Study tip
Always tabulate mass, arm and moment; then verify CG lies within both forward and aft limits.