Flight planning - fuel planning and reserves
Flight planning - fuel planning and reserves tests the fuel breakdown and legal reserves for commercial transport. You must distinguish taxi, trip, contingency, alternate, final reserve, additional and extra fuel.
Fuel policy
- Taxi fuel is burned before take-off; trip fuel runs from take-off to destination.
- Contingency fuel is commonly 5% of planned trip fuel or 5 minutes holding, whichever is greater, subject to operator policy.
- Alternate fuel reaches the destination alternate; final reserve is commonly 30 minutes holding at 1,500 ft above the destination.
- Additional fuel covers specific cases; extra fuel is discretionary. Total fuel = taxi + trip + contingency + alternate + final reserve + additional + extra.
Worked example
Trip fuel is 8,000 kg; contingency at 5% is 400 kg; alternate fuel is 1,200 kg; final reserve is 900 kg; taxi fuel is 200 kg; extra fuel is 300 kg. Total = 8,000 + 400 + 1,200 + 900 + 200 + 300 = 11,000 kg. If tank capacity is 10,800 kg, the flight is not legal as planned; reduce extra fuel or payload, or replan the route.
Traps
Final reserve is not available for normal diversion. Do not forget taxi fuel. Use 5% when it is greater than 5 minutes, not automatically the smaller figure. Recalculate alternate fuel after a reroute or a change of alternate.