Flight Planning and Flight Monitoring under IFR
Planning as a chain of decisions
The IFR flight plan is the output of a chain: route selection, fuel computation, alternate selection, weather minima check, and performance check (takeoff, climb, cruise, landing, missed approach). Each link must be documented and each must remain valid at the moment of departure. Candidates should be comfortable with the standard fuel breakdown: taxi, trip, contingency, alternate, final reserve, and any extra fuel.
Fuel logic
Contingency fuel is a percentage of trip fuel (commonly 5%) or a time-based equivalent; final reserve is a fixed endurance figure (typically 30 minutes at holding speed at 1500 ft above the aerodrome). The trap is adding alternate fuel before contingency or confusing "minimum fuel" with "final reserve". If the flight must divert after the alternate is no longer usable, the pilot is in a fuel-critical situation and must declare it.
Alternates and minima
Know when an alternate is required (destination forecast below specified ceiling/visibility at the expected time of arrival) and the difference between a destination alternate, an en-route alternate, and a takeoff alternate. Weather minima for planning use forecast values, not reported values. A common question gives a TAF and asks whether an alternate is needed: read the whole validity period, not just the arrival hour.
In-flight monitoring
Once airborne, monitoring means comparing actual fuel, time, and position against the plan at each waypoint, and acting early. A rule of thumb: if actual fuel at a checkpoint is below plan by more than the contingency allowance, start planning a diversion rather than waiting for the final reserve to erode.
Worked example
Trip fuel 400 kg, contingency 5% = 20 kg, alternate 60 kg, final reserve 120 kg, taxi 15 kg. Minimum ramp fuel = 400 + 20 + 60 + 120 + 15 = 615 kg. If the question asks for fuel at takeoff, subtract taxi fuel: 600 kg.