Flight Performance and Planning
This domain tests mass and balance, take-off and landing performance, climb, and fuel planning. Questions are numeric and demand that you read POH data correctly and show the arithmetic.
Mass and balance
- Mass, arm and moment: moment equals mass times arm. Total moment divided by total mass gives the CG position.
- Limits: MTOW, MLW, MZFW and the forward and aft CG limits. A forward CG gives more stability and a longer take-off run; an aft CG reduces stability and may cause a tail-stall in the flare.
- Recompute after every change of load, fuel or crew.
Performance
- Density altitude = pressure altitude + 120 x (OAT minus ISA temperature for that altitude).
- Take-off and landing distances increase with mass, altitude, temperature, tailwind, uphill slope, wet or contaminated runway.
- Climb gradient and obstacle clearance are degraded by high temperature and heavy mass - Oman summer conditions are demanding.
Fuel
- Trip fuel, contingency, alternate, final reserve and taxi fuel. A common ICAO Annex 6 planning figure is 30 minutes final reserve by day VFR, 45 minutes at night; confirm against the current OCAR-OPS requirement.
Worked example
Pressure altitude 2,000 ft, OAT 40 C. ISA temperature at 2,000 ft = 15 minus 2 x 2 = 11 C. Difference = 29 C. Density altitude = 2,000 + (120 x 29) = 2,000 + 3,480 = 5,480 ft approximately. Apply the POH chart for 5,500 ft and read the increased ground roll.
Traps
Using airfield elevation instead of pressure altitude; forgetting a 50 percent factor for a tailwind component or a clearway; mixing litres and kilograms without the fuel density.