FUEL PLANNING AND MANAGEMENT FOR CAPTAINS

by Captain Tim Sindall FRAeS

Preamble to Section 7

There is much that could be said on the topic of fuel planning and management. However, the following Section remains focused on how new captains should comply with EU-OPS 1 - the basis of the dissertation - without expanding beyond that. When converting to type, pilots will almost certainly be taught the fuel management procedures applicable to their new aircraft type, to satisfy Company Orders and Legislation.

7.1 INTRODUCTION

Within this appendix, and purely for the sake of consistency, the term ‘captain’ should be taken to mean what is elsewhere described as ‘pilot-in-command’ (International Civil Aviation Organisation – ICAO) or ‘commander’ (UK Air Navigation Order and EU/EU Operations). Although all three terms are similar yet contain subtle differences, it will be easier for the reader if only one of these is used here.

Not until the new captain plans and operates his or her first sector without training staff on board, will responsibility for deciding upon the appropriate fuel quantity required for the flight become apparent. This is an accountability that cannot be truly appreciated for as long as someone else such as a training captain, who has legal responsibility for commanding the aircraft, makes that decision - and signs accordingly!

The purpose of this appendix is to help identify what a captain is expected to consider when deciding how much fuel should be in the tanks when the engines are started and how to manage it thereafter, with the expectation that when the aircraft arrives at its destination, there will still be adequate reserves that can be used in the event that the landing is delayed.

For the sake of clarity, the fuel planning and management model used is that contained in EU-OPS 1 (developed from EU-OPS 1 at Amendment 13). Although the EU/EU-OPS 1 standard, which is applicable to Commercial Air Transport (CAT), exceeds requirements for general aviation (GA). It cannot be read across directly by pilots of helicopters (for whom guidance can be obtained by reading EU-OPS 3 and its successor documents). It nevertheless embodies principles of fuel planning and management that should be of use to captains of both CAT and GA aircraft.

7.2 FUEL PLANNING - GENERAL

ICAO Annex 6 (Operation of Aircraft) Parts I and III (International Commercial Air Transport – Aeroplanes/Helicopters) contains the fundamentals of fuel planning, thus:

A flight shall not be commenced unless, taking into account both the meteorological conditions and any delays that are expected in flight, the aeroplane/helicopter carries sufficient fuel and oil to ensure that it can safely complete the flight. In addition, a reserve shall be carried to provide for contingencies.

All ICAO Contracting States are expected to reflect these two requirements into their national legislation (e.g. UK Air Navigation Order/EU/EU/EASA OPS) and ‘flesh them out’ with detailed guidance as to how they should be interpreted (e.g. to comprise elements such as trip fuel, reserve fuel, etc). Each air operator/air carrier must then specify in their operations manual (OM), for each type of aircraft listed on the air operator certificate (AOC), details of the quantities that must be used in pre-flight fuel planning and in decision-making once the aircraft is in flight (e.g. taxi fuel and the point at which an emergency must be declared).

The most commonly-used format for fuel planning, in effect for deciding before flight what quantity or mass/weight of fuel must be in aircraft tanks before the engines are started, such that the operator’s type-specific instructions are complied with, is a series of elements that together comprise:

a. What is required to satisfy all that can be foreseen if the flight proceeds without hindrance,

b. What is required as a reserve to include what might not reasonably be foreseen (such as not receiving optimal flight levels, diversion to a destination alternate, etc).

7.3 THE EU-OPS 1 FUEL PLANNING MODEL

The usable fuel contained on board before flight will comprise Taxi Fuel, Trip Fuel, Reserve Fuel and Extra Fuel (if required by the captain). Fuel consumption rates and minimum quantities, such as fuel to be used as Final Reserve Fuel, must be specified in the OM and must be realistic. Pre-flight planning must also take account of the anticipated mass/weight of the aircraft, the expected meteorological conditions and air navigation services providers’ procedures and restrictions. (The term ‘weight’ will be used hereafter to mean both ‘mass’ and ‘weight’).

Taking each element in turn: 7.3.1 Taxi Fuel

Taxi Fuel may often be specified in the OM as a ‘standard’ value applicable to each type of aeroplane listed in the AOC, but there are occasions when a more accurate, realistic value may be required. Where prolonged taxiing or other delays can be anticipated after engine start, use of a ‘standard’ value may result in the aircraft commencing its take-off with less fuel on board than desired, leading to a deficit when in-flight fuel consumption checks are first carried out. Conversely, use of the ‘standard’ value where the time between engine start and take-off is expected to be brief may result in the aircraft starting its approach to land at an all-up weight that exceeds its regulated maximum landing weight. This can quite often be a consideration when the aircraft leaves carrying ‘round-trip’ fuel for an ‘out-and-back- flight. Thus, although use of a ‘standard’ value may be perfectly satisfactory for most occasions, this may not always be the case and so any flexibility to increase or decrease the amount specified in the OM should be employed if permitted and the need arises. Fuel likely to be consumed by the APU should be included in Taxi Fuel.

7.3.2 Trip Fuel

Trip Fuel must always reflect all that can reasonably be foreseen for the flight including:

a. Fuel for take-off and climb from the aerodrome elevation to the initial cruising level/altitude, taking into account the expected departure routing,

b. Fuel from top of climb to top of descent, including any step climb/descent,

c. Fuel from top of descent to the point where the approach is initiated, taking into account the expected arrival procedure, and

d. Fuel for approach and landing at the destination aerodrome.

Just as mentioned above under ‘Taxi Fuel’, failure to take proper account of the anticipated departure routing (which probably can be predicted) and the most likely arrival routing (which may be more difficult to predict) can result in a short- fall or excess of fuel once the flight has commenced. As an example, when making a flight from Gatwick with its east/west runway to the Spanish mainland (that lies to the south-west), an easterly initial departure can add some four or five minutes of flight time when compared with departures to the west: the amount of fuel consumed in the process can be similar to the amount calculated as Contingency Fuel. So, if no allowance for the easterly extended routing has been made, the aircraft will have little or no Contingency Fuel remaining from the moment it passes abeam Gatwick on its west-bound heading some four or five minutes after getting airborne! Editors’ Note: Flight Planners will normally be well aware of departure routings to create the initial plan, but rapidly changing weather conditions can mean a runway change, with attendant departure re-routing consequences.

Trip Fuel planning should include all other influences that can be foreseen. These may include: an expectation that the desired cruising flight level(s) may not be granted by ATC due to regular congestion on popular routes; the presence of weather likely to result in track adjustments (significantly prolonging flight time and/or use of higher fuel consumption combating ice accretion); and holding/delayed commencement of the approach-to-land at the destination aerodrome due to commonly-encountered congestion. When these can be termed ‘foreseen’ events, proper allowance should be made for them in the Trip Fuel.

7.3.3 Reserve Fuel

Reserve Fuel will include Contingency Fuel and Final Reserve Fuel (often a type-specific standard amount), may include Alternate Fuel (if an alternate is required), and Additional Fuel (if the nature of flight requires it, e.g. for extended/long range operations, isolated aerodrome operations, etc).

a. Contingency Fuel

This is calculated at the pre-flight planning stage to compensate for those factors that cannot reasonably be foreseen such as deviations of an individual aircraft from the expected fuel consumption data; deviations from forecast meteorological conditions; and deviations from planned/expected routings and cruising levels/altitudes.

There are various ways in which Contingency Fuel amounts can be calculated, but the solutions will never be less than a type-specific minimum value. Operations manuals will always specify which calculation methods may be used for each type operated.

For short-range flights, it may be convenient to use 5% (say) of the planned Trip Fuel. However, for long-range sectors an amount calculated by this means may be excessive, especially where adequate aerodromes can easily be reached from the planned route if an en-route refuelling stop becomes necessary. For such flights, a lesser percentage for the whole time of flight may be acceptable to the national authority, or the latter may permit a specific percentage of Trip Fuel for the latter stage of flight from abeam a usable alternate.

Note that the captain must ensure in such circumstances that the en-route alternate aerodrome chosen for this purpose can really be used if needed, and that low visibility, precipitation or works in progress are unlikely to render it unavailable. Other methods that may be accepted by the authority can include an amount of fuel sufficient for 20 minutes of flight as determined by a fuel consumption-monitoring programme, and a statistical method relating to deviations from planned Trip Fuel, as compared with actual consumption on specific routes.

b. Final Reserve Fuel

This is another element in Reserve Fuel, and comprises, for aeroplanes that have reciprocating (piston) engines, fuel to fly for 45 minutes; and for aeroplanes powered by turbo-jet and turbo-propeller engines, fuel required to fly for 30 minutes at 1,500 ft above the aerodrome in standard conditions at the weight the aircraft is expected to be at that point. Purely for the sake of simplicity, air operators may specify a value that reflects the largest amount likely to be required.

c. Alternate Fuel

When this is required, it should be sufficient for a missed approach from the destination aerodrome’s MDA/DA to the missed approach altitude, a climb to cruising level/altitude, cruise from top of climb to top of descent, descent to the point where the approach is initiated taking into account the expected arrival procedure, and executing an approach and landing. If two destination alternate aerodromes are required, then Alternate Fuel must be sufficient for reaching the furthermost aerodrome. Again, it is important that the routing should be realistic: drawing a straight line between two aerodromes separated by congested airspace may not properly reflect the track miles to be flown and fuel burn likely to be encountered.

d. Additional Fuel

This becomes a Reserve Fuel element when the nature of flight requires its carriage against the possibility that it might have to be used. For example, loss of pressurisation in an aeroplane carrying passengers might necessitate prolonged flight to an en-route alternate at 10 – 12,000 ft resulting in a significantly increased fuel burn. Another example is where the flight proceeds to an isolated aerodrome where once committed beyond a ‘point of safe return’ the pilot has no further option but to land at the intended destination. Additional Fuel is then carried to allow the aircraft to loiter in the vicinity of the destination whilst any unexpected adverse weather passes on and conditions improve, permitting an approach to be made.

7.3.4 Extra Fuel

Extra Fuel is fuel added at the pre-flight stage if required by the captain. This should not be a substitute for foreseen elements, all of which should be included in the Trip Fuel, but may be added if the captain considers it desirable. Some operators provide guidance to captains as to how they would wish the latter to assess the need for carrying Extra Fuel. However, if the captain has reasons for wanting this Extra Fuel on board, he/she should not deprive him/herself of it – provided only that the performance of the aircraft and any limitations (such as the maximum regulated take-off weight, or the maximum regulated landing weight at the destination) are not compromised.

Editors’ note: Do not allow yourself to be pressurised into not taking any additional fuel which you deem necessary. After all, you are in command.

7.4 THE USE OF COMPUTERS TO ASSIST WITH PRE-FLIGHT FUEL PLANNING

Computer-generated hard-copy fuel planning logs (‘plogs’) that depict pre-departure fuel requirements derived from stored data are presented in a form that reflects the operator’s specification. Desirably, each element that comprises the pre-departure fuel requirement will be shown separately, as should the fuel expected to be remaining at various stages of the flight and on arrival at the destination aerodrome, (typically this is Alternate Fuel - when required - plus Final Reserve Fuel). For ease of reference in this document, ‘Alternate Fuel plus Final Reserve Fuel’ is hereafter described as Company Minimum Reserve (CMR) Fuel.

The captain’s responsibility at the planning stage is always to satisfy himself/herself that the fuel required has been calculated correctly according to the information available (weather, routing, all-up weight, etc), regardless as to how that calculation was performed. Obviously, the first form of gross-error check that can be done is by relating to personal experience, gained whilst operating the aircraft; but other benchmarks – such as an understanding of hourly fuel burn for the first and succeeding hours of flight – can help to identify significant under- or over-estimates. Other, more sophisticated methods of estimating how the calculated pre-departure fuel amount should appear may be employed, but the main ‘teaching point’ is that this gross-error check must always be done so as to avoid embarrassment later in the day!

7.5 FUEL MANAGEMENT - GENERAL

EU/OPS 1 make clear that an operator must establish a procedure to ensure that in-flight fuel checks and fuel management are carried out.

7.5.1 Fuel uplift check

Before starting engines the captain must confirm that the total fuel in tanks, as shown in the aircraft technical log, is the same as was requested and shown on the ‘plog’. This amount should be cross-checked by confirming that the actual fuel quantity uplifted from the bowser in litres agrees with what should have been expected (i.e. calculated using an appropriate specific gravity).

a. Gross Error Checks

It may be prudent to establish the units of measurement being used by the fuel supplier. Several different terms can be used, and whilst there are 'ready-reckoner' conversion factors, with which both the ground engineers and the refuellers will be familiar, the risk of human error, particularly under time pressure, cannot be ignored. A 'gross error' check made by the captain should establish if the projected uplift required has been delivered. The check will reveal if there has been any miscalculation that will need to be explained. The error, or possibly fraud, could be that fuel delivered to another aircraft may have been included in the current uplift, if the fuel delivery device flow meter was not 'zeroed' prior to delivery! Additionally, one must also consider prolonged running of the APU by ground/maintenance engineers, who, due to distraction or memory lapse, fail to subsequently adjust the Fuel Remaining figure, shown on the inbound sector of the Technical Log. (See paragraph 7.3.1.above for APU fuel handling). Become very alert where unfamiliar units are being used and hence unfamiliar ‘conversion’ factors. Always take your time and avoid any distractions, as the total uplift may be greater than half the total weight of the departing aircraft.

b. Physical Checks

In extreme circumstances, (remember the MEL might apply) it may be necessary to call for or to carry out a physical check of the contents within the tanks, and it is also pertinent to establish that the fuel required is where it should be, as this can have a significant effect on the aircraft trim. If a physical check is called for, then the 'parked attitude' of the aircraft will need to be included. It may be possible to supply this from the on-board FMS raw data page, failing which there may be physical 'sight gauges', typically in or adjacent to one of the landing gear wheel wells. The 'sense' of applying the indicated attitude correction is vitally important, given the swept-wing dihedral of the modern wing planform. In some aircraft, ‘drip sticks’ may be used. In an ideal world, the transition to command should include participation in aircraft refuelling, together with exercises in making uplifted units conversions and physical distribution resolution, together with attitude corrections.

7.5.2 In-Flight Fuel Checks

In-flight fuel checks should be carried out at regular intervals, recording usable fuel remaining so as to compare actual consumption with planned consumption. Check that this is sufficient to complete the flight and determine the expected amount of usable fuel that will be remaining on arrival at the destination aerodrome. (In summation, these checks are to ensure that the expected amount remaining will not be less than CMR Fuel).

7.5.3 In-Flight Fuel Management

In-flight fuel management describes the processes that the captain may wish to employ when it appears likely that the expected amount remaining will be less than CMR Fuel (and to avoid getting into that situation in the first place). Essentially, it is expected that the captain will decide whether it is acceptable to continue with the current flight plan or to divert to an adequate alternate aerodrome, to be certain of landing with not less than Final Reserve Fuel in either case. Certain in-flight re-planning processes, if these are specified in the OM, may then be employed by the captain, and of course shortening the route, and making changes to the flight level and/or air speed/mach number may help to ensure that CMR Fuel is once again going to be available on arrival at the destination.

7.5.4 Declaring an emergency

Almost certainly the captain will be required to declare an emergency if his/her calculations show that the expected fuel on landing at the nearest adequate aerodrome where a safe landing can be performed will be less than Final Reserve Fuel.

7.6 IN-FLIGHT FUEL RECORDS

It is sensible to make accurate records as the flight proceeds so that trends in fuel burn can be monitored. Many, but not all ‘PLOGS’ depict against selected waypoints what the fuel remaining should be if CMR Fuel is to remain at the destination. So, if no Contingency Fuel has been consumed, this will still be part of the fuel remaining at the waypoint and show as an excess. If the ‘PLOG’ does not depict predicted in-flight fuel remaining as described (i.e. CMR Fuel