2		Fuel Policy and Fuel Monitoring

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Reserve Fuel

Contingency Fuel

An operator must ensure that every flight carries sufficient fuel for the planned operation, and reserves to cover any replanning necessary for in-flight contingencies. A contingency is a chance occurrence or unforeseen event. Contingency Fuel is carried to compensate for deviations:

•Of an individual aircraft from the expected fuel consumption data

•From the forecast meteorological conditions

•From the planned routing and/or cruising levels/altitudes.

Alternate Fuel

Alternate Fuel is simply the fuel required to fly from missed approach at the destination to the planned alternate. It should take into account probable routing and expected wind component, but it does not have its own allowance of contingency fuel. Contingency allowance is applied only to the trip fuel.

Final Reserve Fuel

If you fly from departure to destination, use the contingency fuel en route, and then have a missed approach at the destination and fly to the alternate, you will have no fuel left on arrival. We therefore have a minimum landing fuel, and you should normally never land with less than the Final Reserve Fuel. It consists of 30 min (jet/turboprop) at 1500’ above AAL in ISA conditions, or 45 min (piston engine aircraft) fuel consumption at endurance speed.

Additional Fuel

Contingency, Alternate and Final Reserve fuel cover most cases, and provided that suitable diversions are available en route and near the destination, this is all that is required for Reserve Fuel. There are two cases, however, where Additional Fuel may be needed:

No Alternate

This is also known as the “Island Holding” situation. If there is no alternate available at some isolated aerodrome, then you need to be able to cope with the aircraft landing two minutes ahead of you bursting a tyre on the runway, or possibly a short duration tropical squall going through.

No En Route Alternate and Inability to Hold Height

If you are a long way from an alternate and you suffer some malfunction which requires you to reduce to a lower altitude (engine failure or pressurization failure or both), you may have to fly a long portion of the flight at a higher fuel consumption than planned. In this case you may need Additional Fuel.

EU-OPS policy states minimum Additional Fuel should be sufficient to permit:

a.If an engine fails or the pressurization is lost at the most critical point, the aircraft to descend as necessary and proceed to an adequate alternate aerodrome and hold at 1500 ft for 15 minutes above the aerodrome elevation in ISA conditions

except that this additional fuel is not required if adequate basic trip, contingency, alternate and final reserve is sufficient to complete the above profile and

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b.Holding for 15 minutes at 1500 ft above the destination aerodrome in ISA conditions when a flight is operated without a destination alternate aerodrome

On most flights Additional Fuel is not required but in either of the above cases, it may be necessary.

Calculation of Contingency Fuel

Numerical calculation of taxi, trip, alternate and final reserve fuels is fairly straightforward. Taxi fuel is usually a standard allowance. Trip fuel and alternate fuel are extracted from graphs or tables from the appropriate Operational Flight Manual. We will practise this process in Chapters 3, 4 and 5. Final reserve fuel is a simple calculation based on 30 (jet/turboprop) or 45 (piston) minutes hold at endurance speed. However, contingency fuel can vary depending on the type of operation.

Contingency Fuel is the higher of A and B below:

A

As agreed with the appropriate national aviation authority:

•5% of the planned trip fuel, or, in the event of in-flight replanning, 5% of the trip fuel for the remainder of the flight. No en route alternative is needed in this case.

•If the operator has a fuel monitoring programme and agrees a particular method of statistical analysis which includes standard deviations (the details need not concern us for the purposes of the ATPL), this can be reduced yet further by agreement with the authority.

B

An amount to fly for 5 minutes at holding speed at 1500 ft (450 m) above the destination aerodrome in standard conditions.

For the most part the contingency Fuel will be based on 5% of trip fuel but be aware of the alternate B because questions do occur when holding for 5 minutes at 1500 ft will be a HIGHER figure.

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2		Fuel Policy and Fuel Monitoring

Monitoring Fuel and Policy Fuel 2

Fuel Policy - Worked Examples

Example 1

Jet aircraft. Taxi fuel is 60 kg. Cruise fuel flow is 5000 kg/h. Hold fuel flow is 3000 kg/h. Flight time is 2 h 30 min. Contingency is 5% of trip fuel. Alternate fuel is 900 kg. What is the required ramp fuel?

Taxi		60
Trip	5000 kg/h × 2.5 h	12 500
Reserve
Contingency		625
Alternate		900
Final Reserve	30/60 × 3000	1500
Additional		Not required
Extra		Not required
Total ramp fuel		15 585 kg

Example 2

Jet aircraft. Taxi fuel is 100 kg. Trip fuel is 5325 kg. Hold fuel is 6000 kg/h. Alternate fuel is 4380 kg. Contingency is the higher of 5% trip fuel or 5 minutes of holding at 1500 ft.

What is minimum required take-off fuel?

a.12 971 kg

b.14 500 kg

c.13 205 kg

d.13 370 kg

Ans: c

Example 3

Piston aircraft. Taxi fuel 20 lb. Cruise fuel flow 150 lb/h. Hold fuel flow 60 lb/h. Flight time 1 hour 20 min. Alternate fuel 40 lb.

Assuming minimum fuel uplift, normal en route diversions available and that contingency fuel is not used en route, what will be your fuel on arrival at the alternate?

a.315 lb

b.95 lb

c.57 lb

d.295 lb

Ans: c

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Example 4

Piston aircraft. Taxi fuel 20 lb. Cruise fuel flow 150 lb/h. Hold fuel flow 60 lb/h. Flight time 1 hour 20 min. Alternate fuel 40 lb.

Assuming minimum fuel uplift, normal en route diversions available and that contingency fuel is not used en route, what will be your fuel on arrival at the destination after a 20 minute hold?

a.87 lb

b.97 lb

c.57 lb

d.77 lb

Ans: d

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