FUEL POLICY AND FUEL MONITORING

Universal Application of Fuel Policy

The principles which establish how much fuel should be carried on an air transport flight have been internationally agreed and are laid down in CS-OPS 1. Whilst the actual amounts vary from aircraft type to type, because different aircraft have different fuel consumptions, the rules by which the minima for each flight are calculated are universal.
This is known as EASA Fuel Policy.

Realistic Trip Fuel

The operator shall ensure that the planning of flights is based only upon:
• Procedures and data derived from the Operations Manual or current aeroplane specific
data.
• The conditions under which the flight is to be conducted, including:
• Realistic fuel flows expressed as kg/h, lb/h or gal/h;
• The aircraft's anticipated weights (masses)
• Expected meteorological conditions; and
• Air Traffic Service procedures and restrictions

EASA Fuel Policy - Breakdown of Fuel

Under EASA fuel policy, fuel is considered under the following breakdown:

Taxi Fuel
The amount required to start up, taxi, and hold (if necessary) before take-off. It will also include any fuel required to operate pre-flight services, such as cabin conditioning, and may include use of the APU. In the Boeing 737, for instance, 260 kg of Taxi Fuel is allowed. This is over a quarter of a tonne of fuel before take-off.

Trip Fuel
This should include fuel:
• For the take-off from the airfield elevation, the departure procedure (SID) and thence to
the top of climb (TOC) at the initial cruising level/altitude.
• From the TOC to top of descent (TOD), including any step climbs or descents.
• From TOD to the point where the approach is initiated; account is taken of expected arrival
procedures (STARs).
• For approach and landing.

Reserve Fuel
Reserve Fuel is further subdivided into:
• Contingency Fuel
• Alternate Fuel
• Final Reserve
• Additional Fuel
Each of these will be dealt with separately shortly.

Extra Fuel
Extra Fuel is any fuel above the minima required by Taxi, Trip and Reserve Fuel. It can simply be because more has been uplifted than is required for the trip, so the surplus is defined as Extra Fuel or, more usually, it can be because, even when all the minima required by EASA fuel policy are carried, the aircraft commander decides that more is needed because of particular circumstances.

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 ReserveFuel. 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.

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

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 practice 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.

Fuel Monitoring
Having planned the expected fuel consumption, we now have to ensure that the aircraft is performing closely to the plan, and take appropriate action if it does not.
A commander must ensure that fuel checks are carried out in flight at regular intervals. The fuel remaining must be recorded and evaluated to:
• Compare actual consumption with planned consumption
• Check that the remaining fuel is sufficient to complete the flight
• Determine the expected fuel remaining on arrival at the destination
The relevant fuel data must be recorded.
If, as a result of an in-flight fuel check, the expected fuel remaining on arrival at the destination is less than the required alternate fuel plus final reserve fuel, the commander must take into account the traffic and the operational conditions prevailing at the destination airfield, along the diversion route to an alternate aerodrome and at the destination alternate aerodrome, when deciding to proceed to the destination aerodrome or to divert, so as to land with not less than final reserve fuel.
Modern major carriers use computer flight planning. Either they install their own dedicated ground flight planning computer, such as BA's CIRRUS system or Lufthansa's LIDO system, or they subscribe to a commercially available system such as JETPLAN. The computer output is usually in the form of large sheets of fanfold paper and a typical print-out is shown on the next page. Line 18 in this example is a list of the titles of each column and the last entry is "REM". This means "Fuel Remaining". Look down the columns and you will see that for each waypoint (KONAN, KOKSY, REMBA, etc) there is a REM value (0045, 0043, 0038, etc). This is the minimum fuel that should remain (in hundreds of kilogrammes) overhead the waypoint (i.e. 4500 kg, 4300 kg, 3800 kg, etc). All that the pilot has to do is check as he passes over each waypoint that the fuel remaining is not less than the flight plan fuel and he then knows that he has sufficient to complete the trip and arrive with appropriate reserves.

 For longer flights, it is also necessary to keep a track on the fuel consumption trend. We may have adequate reserves at the start of a trip but if the fuel consumption rate is higher thanforecast we may go below the minimum requirement at a later stage of the flight. We need to have adequate early warning of the fuel flow as well as the total quantity. On sophisticated modern aircraft this is accomplished by use of the Flight Management System. The fuel contents and the fuel flow-meter readings are passed directly into the Flight Management Computer (FMC). The FMC also knows the route distance to go, the current ground speed and the anticipated descent profile. From this    it can work out the expected fuel on arrival. This is available for the pilots to check at any time. This expected arrival fuel is also compared with the sum of the alternate fuel and the final reserve fuel. If it goes below this sum, a warning to the pilots is displayed on the Control and Display Unit (CDU). For aircraft without an FMS, the 'Howgozit' fuel graph is the usual method. A graph is drawn with 'Fuel Remaining' as the 'y' axis and 'Distance to Go' as the 'x' axis. See the example at Figure 2.2. Note: Questions on the 'Howgozit' are not set in the EASA exam. This is simply to help your understanding of fuel monitoring. In this example, we are assuming that we have a flight of 1000 nautical ground miles. We have to land with 1000 kg (our final reserve fuel) and the fuel required to fly to the alternate is 700 kg. Therefore our minimum on arrival at the destination is 1700 kg.
 (Just out of interest, note that the slope changes shortly after the start. This is because aircraft usually climb at a slower speed than cruise, but the engines are at or near max continuous power in the climb but at cruise power when level).
 We are expecting to use 5000 kg en route, so this is our trip fuel. Our contingency will be 5% of the remaining trip fuel, so this will be 250 kg at the start of the trip, reducing to zero at the end. Our minimum take-off fuel is therefore 6950 kg.
Now, although we must have our contingency fuel on board, very often we do not use it.
  After all, the trip fuel is supposed to be based on a realistic figure. Therefore the contingency is only to cover unforeseen fuel consumption deviations, incorrect met forecasts and unexpected ATC re-routing. On the majority of trips, these should not occur. In these cases, the fuel will track down the 'probable fuel consumption' line and we will arrive with the contingency fuel unused.
During the flight we take fuel checks every half hour (or other interval, as specified in the
company's Flight Operations Manual). From these we build up the history of the fuel
consumption and establish a trend. Extrapolating the slope will indicate to us the expected arrival fuel if the trend continues. In Figure 2.3, for instance, we are going to arrive with sufficient fuel. In Figure 2.4, we are not. In this case, appropriate action would have to be considered, such as returning to the departure airfield or diverting to a suitable en route airfield to up-lift fuel.

A check of the aircraft's fuel system may be required if it was thought that the excess
consumption was caused by a fuel leak or a fuel-gauge fault. An error in computation at
flight planning or in the actual fuel amount up-lifted at departure may have been the cause of the short- fall. Aircraft have run short of fuel. Very strong un-forecast headwinds have been encountered. Pounds to kilograms, kilograms to pounds, have been erroneously converted and specific gravities applied incorrectly!

Special Cases 1 - Decision Point Procedure
There is a special case when we may get airborne without sufficient contingency fuel for theplanned trip to the destination. This is called decision point procedure.

Decision Point Procedure - A Typical Scenario

Consider the 'Howgozit' in Figure 2.6. A flight from Oxford to Faro, in southern Portugal, is planned. There are alternates near Faro - Seville or Jerez, for instance. The total of the final reserve fuel and the alternate fuel is 3000 kg. The trip fuel is exactly 10 000 kg. There is a suitable en route diversion at Lisbon, so contingency fuel is 3%, which comes to 300 kg. This means that we need 13 300 kg at take-off.

 Unfortunately, the maximum capacity of our fuel tanks means that we can get in only 13 150 kg at take-off. This is 150 kg short of the minimum requirement. Does this mean that we cannot do this flight? Not necessarily, if there is a suitable en route alternate. We define the top of descent for going into Lisbon, our alternate, as the Decision Point.

 We have plenty of fuel to proceed to Lisbon, so this is legal. At this Decision Point, we carry out a fuel check. Unless unforeseen circumstances have arisen, we will probably not have used the contingency fuel and so will still have 150 kg above the expected consumption line for Faro.

 The requirement for contingency fuel is 3% above the trip fuel required for the remainder of the flight, not the start trip fuel. At this stage of the trip, the required contingency fuel is only 55 kg. If the fuel remaining includes this 55 kg contingency fuel plus the remainder of the trip fuel for Faro (along with the usual alternate fuel and final reserve fuel), we continue to Faro. If the fuel remaining comes to less than this figure, we divert to our alternate, Lisbon.

 Decision Point Procedure should not be attempted unless the departure fuel is sufficient to guarantee a reasonable expectation of there being enough fuel remaining at the Decision Point to permit continuation to the scheduled destination. The success of a Decision Point Procedure will depend on whether unforeseen events, such as not being cleared to the optimum cruise level or avoidance of weather, have caused the contingency fuel allowance to be used. The normal non-consumption of contingency fuel, which can be a considerable amount (usually 3% at least of the fuel between departure and Decision Point), permits Decision Point Procedure to be feasible and safe.

 Comparing the Decision Point Procedure fuel requirement with the normal fuel requirements, the maximum fuel reduction available is the contingency fuel (3% or 5% of trip fuel) between Departure and Decision Point.

Alternatively, we can say that contingency fuel can be reduced down to that required
between Decision Point and Destination.

Special Cases 2 - Isolated Aerodrome Procedure
 An 'Isolated' aerodrome is defined as an aerodrome for which there is no Destination Alternate. An island in an ocean is a good example, for instance, Easter Island in the South Pacific. In this case  the aircraft might have to hold for longer than usual (e.g. in the case of a blocked runway or a tropical storm passing through) with no option of diverting. Reserves normally consist of contingency fuel, alternate fuel and final reserve fuel. In the case of an Isolated aerodrome there is no alternate, so there is no alternate fuel. Instead, for a jet or turboprop aircraft, the combination of final reserve fuel and additional fuel must comprise enough fuel to fly for two hours at normal cruise consumption after arriving at the destination aerodrome. CS-OPS 1
specifies that the fuel must include:
• Taxi fuel
• Trip fuel
• Contingency fuel
• Additional fuel if required but not less than:

• For aeroplanes with reciprocating engines, fuel to fly for 45 minutes plus 15% of the
flight time planned to be spent at cruising level, or two hours, whichever is less.

• For aeroplanes with turbine engines, fuel to fly for two hours at normal cruise consumption
after arriving overhead the destination aerodrome, including the final reserve fuel.

CS-OPS 1 EASA LINK BELOW: