Fuel decision at the destination-hold point
A twin-jet is planned from Amsterdam (EHAM) to Madrid (LEMD). The operational flight plan shows taxi fuel 250 kg, trip fuel 5,200 kg, contingency 5% of trip fuel, alternate fuel to Zaragoza (LEZG) 900 kg, final reserve 650 kg (30 min at 1,300 kg/h) and additional fuel 150 kg. Take-off fuel is 7,160 kg. The aircraft is now 50 min from Madrid with 2,900 kg remaining. Cruise fuel flow is 1,300 kg/h. ATC advises that Madrid will require a 15-min hold, and the crew expects the same fuel flow in the hold. Zaragoza is forecast CAVOK. The present position is 180 NM from Zaragoza with an expected ground speed of 420 kt. Company policy protects the final reserve and permits contingency fuel to be used for unforeseen holding, but not for a planned diversion.
1. Calculate the fuel required from the present position to land at Madrid with the 15-minute hold and the final reserve intact. Can the crew accept the hold? Explain how the contingency allowance affects the answer.
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Fuel to Madrid: 50 min at 1,300 kg/h = 1,083 kg. Hold: 15 min at 1,300 kg/h = 325 kg. Add alternate 900 kg and final reserve 650 kg:
1,083 + 325 + 900 + 650 = 2,958 kg required.
Available is 2,900 kg, so the deficit is 58 kg. The contingency figure of 260 kg is not extra fuel in the tanks; it is already part of the 2,900 kg remaining. It may be used for unforeseen holding, but it cannot be added a second time. Even using all usable contingency/additional allowance, the crew would still land below the protected final reserve or would have insufficient fuel for the filed alternate. Therefore do not accept the hold; divert to Zaragoza.
2. Calculate the fuel needed to divert from the present position to Zaragoza and state the minimum fuel at touchdown. What common error must be avoided when using the flight-plan alternate figure?
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Diversion time = 180 NM / 420 kt = 0.429 h = 25.7 min. Diversion fuel = 1,300 × 0.429 = 557 kg. Minimum at touchdown = final reserve 650 kg. Total required from present position = 557 + 650 = 1,207 kg. With 2,900 kg available, the margin is 1,693 kg, so the diversion is comfortably feasible.
The common error is to use the 900 kg alternate fuel directly. That figure is the fuel from Madrid to Zaragoza, not from the present position. The present-position diversion fuel must be computed from the actual distance and ground speed; otherwise the crew may believe it has less or more fuel than it really has.
3. State the actions and ATS communication if the crew decides to divert.
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The crew should advise ATC immediately that they are diverting to Zaragoza, request the appropriate clearance and revised route, and state the reason (destination hold plus fuel). They should amend the flight plan/company flight following, confirm Zaragoza handling and weather, and monitor fuel against the new plan. There is no need to declare an emergency or MINIMUM FUEL at this stage because the computed margin is large. If fuel later falls below the diversion plan such that any further change would cause landing below final reserve, the crew should declare MINIMUM FUEL; if the final reserve itself is threatened, declare MAYDAY FUEL.