Fuel Planning with a Reclearance and a Holding Requirement
A twin-jet is planning a flight of 2,200 nm from a departure airport to a destination airport. The planned cruise is at FL370 with a true airspeed of 460 kt and a headwind of 50 kt, giving a ground speed of 410 kt. The fuel flow at cruise is 2,300 kg/h. The taxi fuel is 200 kg, the climb fuel is 1,800 kg, and the descent fuel is 600 kg. The destination forecast is for thunderstorms, and the crew plans a 30-minute hold at the destination before landing. The alternate is 150 nm away with a 20-minute flight at 400 kt ground speed and a fuel flow of 2,000 kg/h. The required reserve is 30 minutes of holding fuel at 1,500 ft, which the AFM gives as 1,100 kg/h. The aircraft has a maximum fuel capacity of 16,000 kg, and the crew is planning to load 13,500 kg.
1. Calculate the total fuel required for the flight, including the hold and the alternate, and compare with the planned fuel load.
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The cruise time is 2,200/410 = 5.37 hours, and the cruise fuel is 5.37 x 2,300 = 12,351 kg. The total fuel required is taxi 200 + climb 1,800 + cruise 12,351 + descent 600 + hold 30 minutes at 2,300 kg/h = 1,150 kg + alternate 20 minutes at 2,000 kg/h = 667 kg + reserve 30 minutes at 1,100 kg/h = 550 kg. The sum is 200 + 1,800 + 12,351 + 600 + 1,150 + 667 + 550 = 17,318 kg. The planned fuel load of 13,500 kg is far below the requirement, and even the maximum fuel capacity of 16,000 kg is insufficient. The crew must reduce the payload, plan a fuel stop, or choose a closer alternate. The shortfall against the maximum capacity is 17,318 - 16,000 = 1,318 kg, so the flight cannot be made as planned.
2. The crew considers reducing the hold to 15 minutes and using a closer alternate 80 nm away. Recalculate the fuel required.
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With a 15-minute hold, the hold fuel is 15/60 x 2,300 = 575 kg. The closer alternate is 80 nm away at 400 kt ground speed, so the time is 80/400 = 0.2 hours = 12 minutes, and the fuel is 0.2 x 2,000 = 400 kg. The reserve remains 550 kg. The total is 200 + 1,800 + 12,351 + 600 + 575 + 400 + 550 = 16,476 kg. This is still above the maximum fuel capacity of 16,000 kg by 476 kg. The crew must reduce the cruise fuel by reducing the payload or planning a lower cruise speed, or plan a fuel stop. The reclearance option, where the crew plans to a point and then reclears to the destination, could allow a lower fuel load if the reclearance point has a suitable alternate, but the total fuel required must still cover the worst case.
3. Explain how the reclearance procedure could change the fuel planning and the reserve requirement.
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A reclearance procedure allows the crew to plan to an intermediate point and then, in flight, reclear to the destination if the weather and fuel permit. The advantage is that the crew can plan a lower fuel load because the reclearance point has its own alternate and reserve, and the destination weather is assessed later. The disadvantage is that if the reclearance is not available, the crew must divert to the reclearance alternate, which may require more fuel than planned. The reserve requirement is still the 30-minute hold at 1,500 ft, but the alternate fuel may be lower if the reclearance alternate is closer. In this case, the reclearance could reduce the alternate fuel from 667 kg to, say, 400 kg, bringing the total to about 17,051 kg, still above the maximum capacity. The crew should therefore plan a fuel stop or reduce the payload, and use the reclearance only as a contingency.