Flight Planning and Flight Monitoring
Flight Planning and Flight Monitoring tests the fuel, time and diversion calculations behind the operational flight plan, and your ability to check that the plan is holding up in flight. Expect triangle-of-velocities work, fuel policy and equal-time-point questions.
Fuel and the PLOG
- A typical fuel plan contains taxi, trip, contingency (5% of trip fuel, or 3% when no destination alternate is required), alternate, final reserve (30 minutes holding at 1,500 ft for turbine aircraft) and additional fuel.
- The PLOG combines true track, wind velocity, TAS and distance to give leg time and fuel. In flight, compare fuel used and fuel flow with the plan at each waypoint.
ETP and PNR
- The equal time point is where the time back to the departure airfield equals the time on to the destination; it lies towards the destination when the outbound leg has a headwind.
- The point of no return is the last point from which the aircraft can return with reserve fuel intact.
Worked example
A to B is 1,000 NM, TAS 400 kt, outbound headwind 50 kt, return tailwind 50 kt. Ground speed out = 350 kt, back = 450 kt. At the ETP, x/450 = (1,000 − x)/350. Cross-multiplying gives 350x = 450,000 − 450x, so 800x = 450,000 and x = 562.5 NM from A. The ETP lies beyond the midpoint because the outbound headwind makes the outbound leg slower.
Traps
- Using TAS instead of ground speed in ETP and PNR calculations.
- Taking contingency as a percentage of total fuel rather than of trip fuel.
- Forgetting that a changed cruise level alters both TAS and fuel flow, so the PLOG must be reworked.