Fuel Planning
Fuel Planning tests the legal fuel figure you must carry and the order in which the components are built. The exam expects a defensible fuel plan, not a single 'trip fuel plus a bit' number, and it checks that you know which fuel is usable for diversion and which is protected.
Fuel components
For commercial planning, the common build-up is:
- taxi fuel;
- trip fuel to destination;
- contingency fuel, typically 5% of trip fuel (use the figure in the approved manual);
- destination alternate fuel, if an alternate is required;
- final reserve fuel;
- additional fuel for a specific operational need;
- extra fuel at the commander's discretion.
Final reserve is protected: it is not available for normal planning. Many CPL piston syllabi use 45 minutes holding at 1,500 ft above the aerodrome in ISA; commercial turbine operations commonly use 30 minutes. Use the figure stated in your operator's or school's approved manual.
Worked example
Trip fuel 120 L; contingency 5% = 6 L; alternate 25 L; final reserve 45 min at 30 L/h = 22.5 L; taxi 5 L. Total = 120 + 6 + 25 + 22.5 + 5 = 178.5 L. At avgas density 0.72 kg/L, mass = 178.5 × 0.72 = 128.5 kg. If the aircraft's fuel tank capacity is 150 L, the plan is not feasible without reducing the alternate, adding fuel stops or changing the destination; the reserve cannot simply be deleted.
Traps
Confusing litres with kilograms; applying contingency to total fuel rather than trip fuel; counting final reserve as diversion fuel; omitting taxi fuel; and using a density taken at the wrong temperature. A fuel plan that only balances on paper but exceeds tank capacity is invalid.