Commercial Pre-Flight Fuel Planning
Alternate Selection Requirements
- Standard: At least one destination alternate must be selected.
- Two Alternates: Required if:
- Weather at destination is marginal ($< 2,000$ ft ceiling or $< 3$ miles visibility) for 1 hr before/after ETA.
- No meteorological information is available for destination.
Special Fuel Procedures
Isolated Aerodrome Procedure
If no suitable alternate exists (e.g., island destination):
- Carry fuel to fly to destination.
- Additional fuel to fly for 2 hours at normal cruise consumption (final reserve included).
Predetermined Point (PDP) Procedure
Used when the destination alternate is not available or reliable. The flight plan includes a PDP where a decision is made to either:
- Continue to destination and land with mandatory reserves.
- Divert to an en-route alternate.
Reduced Contingency Fuel (RCF)
Allows carrying less than 5% contingency fuel by using a Decision Point en-route.
- At the Decision Point, the pilot checks fuel.
- If fuel $\ge$ Required Fuel to Destination + Reserves, continue.
- If fuel $<$ Required, divert to a closer alternate (commercial stop).
- Typically reduces contingency to 3% or 5 minutes (whichever is greater).
Factors Calculating Fuel
Fuel planning must take into account:
- Expected taxi time.
- Expected departure/arrival routes (SIDs/STARs).
- Forecast meteorological conditions (wind/temp).
- Mass of the aeroplane.
- Performance data (fuel flow charts).