Flight Planning & Monitoring

An airline flight plan is a legal document and a fuel contract: it shows that the flight can reach its destination – and an alternate – with fixed reserves, whatever reasonable surprises happen on the way. This lesson covers how an airline plans fuel and alternates, how it builds the operational flight plan (OFP) and how the crew monitors fuel in flight.

1. The operational flight plan

The OFP, prepared by dispatch or flight planning software and accepted by the commander, contains:

• Route, cruise levels, cost index and the waypoint-by-waypoint log (tracks, distances, winds, temperatures, times and fuel remaining).
• The fuel breakdown and the planned weights (ZFW, TOW, LW) against their limits.
• Alternates, weather and NOTAMs for departure, destination, alternates and the en-route airports.
• Equal time points and en-route alternates for long or remote sectors.

The ATC flight plan is filed separately – usually at least 3 hours before off-block for flights in congested airspace, and no later than 60 minutes otherwise.

2. Fuel policy

Part	Typical rule (EASA)
Taxi fuel	Expected start-up and taxi, plus APU
Trip fuel	Take-off, climb, cruise, descent and approach to the destination, using the forecast winds
Contingency fuel	Usually 5% of trip fuel (3% with an en-route alternate, or less with approved statistical methods), but never less than 5 minutes holding at 1,500 ft above the destination
Destination alternate fuel	Missed approach at the destination, climb, cruise, descent and approach at the alternate
Final reserve fuel	30 minutes holding at 1,500 ft above the alternate (jets)
Additional fuel	When needed – for example to reach an en-route alternate after an engine failure or depressurisation at the critical point
Extra / discretionary fuel	Added by the commander for expected delays, weather or ATC holding

Example: trip 6,200 kg, contingency 5% = 310 kg, alternate 1,600 kg, final reserve 1,100 kg, taxi 200 kg. Minimum block fuel = 9,410 kg plus any extra.

Airlines also use tankering (carrying fuel for the next flight when it is cheaper at departure) – a cost decision that adds weight and fuel burn.

3. Alternates

• A destination alternate is needed unless the flight is short and the destination has two separate runways and good weather – or it is an isolated aerodrome (then extra fuel replaces the alternate: for jets about 2 hours at normal cruise above the destination, including final reserve).
• A take-off alternate is needed when the departure weather is below landing minima; it must be within 1 hour (twins) at the one-engine-inoperative speed.
• Planning minima: an alternate is only usable if its forecast is better than the landing minima by a margin – for example a non-precision approach needs the MDA plus 200 ft and visibility plus 1,000 m.
• Two destination alternates are needed when the destination forecast is below minima or unavailable.

4. EDTO / ETOPS planning

For twins flying beyond 60 minutes from an adequate aerodrome, the route is planned within the approved diversion time (for example 120 or 180 minutes) of en-route alternates with suitable forecast weather. The critical fuel scenario – a depressurisation, with or without an engine failure, at the worst point – must be covered by the fuel on board.

5. Decision point and reclearance

On long flights an airline may plan to a closer decision point destination with less contingency fuel, then decide in flight whether to continue to the planned destination (reclearance or "redispatch"). It saves fuel on long sectors while keeping legal reserves.

6. Flow management and slots

• In busy airspace, the flow management unit gives a CTOT (calculated take-off time), usually with a window of −5 to +10 minutes.
• Airports using A-CDM (collaborative decision making) give a TOBT (target off-block time) and TSAT (target start-up approval time).

7. In-flight fuel monitoring

• At each waypoint, compare the fuel remaining with the OFP. A growing deficit means stronger headwinds, a different level, a heavier aircraft – or a fuel leak: check that fuel used + fuel on board equals the departure fuel.
• Recalculate the expected landing fuel and compare it with alternate fuel plus final reserve.
• Declare "MINIMUM FUEL" to ATC when you are committed to land at a specific aerodrome and any change to the clearance may make you land with less than final reserve fuel. It is not an emergency, but it warns ATC.
• Declare "MAYDAY FUEL" when the calculated fuel on landing at the nearest suitable aerodrome will be less than final reserve.

8. Monitoring the flight

• Track progress against the OFP times; update the ETA and expected fuel.
• Keep the weather picture current: ATIS and VOLMET for the destination and alternates, SIGMETs on the route.
• Before descent: compare the landing fuel, the weather and the approach expected – and decide early if a diversion is likely.

Flying it at Levant

Every SimBrief OFP you load for a Levant flight shows the same fuel breakdown: taxi, trip, contingency, alternate, final reserve and extra. During the flight, compare the fuel at each waypoint with the plan; if you start eating into the reserves, decide on a diversion early – on IVAO you can declare minimum fuel exactly as in real operations.

Check yourself

1. What is the usual contingency fuel? 5% of trip fuel, but not less than 5 minutes holding at 1,500 ft.
2. How much final reserve does a jet carry? 30 minutes holding at 1,500 ft above the alternate.
3. When do you declare "MINIMUM FUEL"? When committed to an aerodrome and any change could make you land below final reserve.
4. When do you declare "MAYDAY FUEL"? When the calculated landing fuel will be less than final reserve.
5. Fuel used + fuel on board is 800 kg less than the departure fuel. What do you suspect? A fuel leak.

Simulation training material based on EASA-style fuel policy. Each operator's approved fuel policy applies in real operations.