Flight planning and monitoring
Flight planning and monitoring tests the paperwork and arithmetic that turn an intended route into a legal, fuel-safe flight, and the in-flight checks that confirm the plan still works.
The plan
A PLOG holds headings, TAS, wind, ground speed, leg times, distances and fuel. The wind triangle gives heading and ground speed; variation and deviation convert between true, magnetic and compass. Mass at takeoff is empty mass + payload + fuel, checked against MTOW and the runway/obstacle performance. Fuel is planned as: taxi + trip + contingency (typically 5% of trip) + alternate + final reserve (commonly 30 min VFR by day, 45 min IFR/night) + any extra. The ICAO flight plan needs aircraft identification, type, route, levels, EET and alternate.
Worked example
Trip 2.0 h at 32 L/h = 64 L. Contingency 5% = 3.2 L. Alternate 0.4 h = 12.8 L. Final reserve 45 min = 24 L. Taxi 10 min = 5.3 L. Total = 109.3 L. At 0.72 kg/L that is about 78.7 kg, which must be added to the mass and balance.
In flight
Compare actual fuel flow and ground speed with the PLOG at each waypoint; a 10% speed loss on a 2 h leg costs 12 min and about 6.4 L. Re-plan if the alternate falls below minima, if fuel at destination would be under final reserve, or if a diversion is required.
Traps
Applying contingency to total fuel instead of trip fuel; forgetting taxi fuel; using TAS for leg time; converting litres to kg with the wrong density; planning to destination with no alternate when one is required.