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2	FUEL MANAGEMENT AND SAFETY FUEL MANAGEMENT AND SAFETY Accurate and efficient fuel management on the part of the airline and flight crews improves safety, because it requires additional attention, accuracy and increased situational awareness. By accurately managing fuel, airlines can: Ensure that proper risk management processes for fuel boarding are in place by carrying enough fuel to the high-risk airports and less fuel to airports where it is not required. Minimize the risk of unplanned fuel diversions Ensure that flights land with adequate fuel on board Ensure that crews maintain a safe and efficient approach to fuel management
3	FUEL MANAGEMENT AND THE ENVIRONMENT FUEL MANAGEMENT AND THE ENVIRONMENT A 1% saving in fuel for a B737-300 aircraft will result in a yearly reduction of fuel consumption by 100 metric tons (32,835 US Gal) and save airlines approximately USD$50,000 per aircraft. It will also decrease the emission of pollutants by the following amounts: 318.7 tons of CO2; 123.9 tons of H2O; 2.112 tons of NOx; 98 kg of SO2; and 56 kg of CO
4	ECONOMIC IMPACT OF EFFICIENT FUEL MANAGEMENT ECONOMIC IMPACT OF EFFICIENT FUEL MANAGEMENT Fuel is the second largest cost item after employee wages. For some airlines, fuel represents approximately 20% or more of the total budget. Airlines that have an aggressive fuel saving program can reduce their overall fuel budget by at least 5%. Fuel savings directly affect the bottom line. In an environment of extreme competition, airlines that manage fuel efficiently will have a definite competitive advantage. Because of low profit margins, to compensate for each dollar wasted in fuel burn, airlines would have to generate 15 to 20 dollars in additional revenues to achieve the same profit. All departments including Flight Operations must be accountable for efficient fuel management. Effective communications, efficient procedures, adequate training programs and proactive management of each flight will minimize overall corporate costs (fuel, time cost, connections, etc) and ensure the company’s success. For example, by slowing down flights scheduled to arrive early not only saves fuel, but also reduces emissions and, in some cases, prevents ramp and gate congestion. On-time arrivals improve ground staff efficiency and customer service.
5	ECONOMIC IMPACT OF EFFICIENT FUEL MANAGEMENT Airlines must sensitize government regulators to the additional costs such as delays, fuel and emissions, which result from certain regulations, inefficient ATC route structure and excessive ATC restrictions. Some of the factors that contribute to an increase in fuel consumption and gas emissions include insufficient ATC staffing, inadequate and antiquated equipment, inefficient and cumbersome procedures, unnecessary route or altitude restrictions for controllers’ convenience, restrictive and inflexible noise abatement procedures, and poor communication facilities.
6	BASIC FACTS REGARDING FUEL CONSUMPTION BASIC FACTS REGARDING FUEL CONSUMPTION Airlines perform limited maintenance to their fleet due to the cost of aircraft down time or spare engines. Regular maintenance contributes to an airplane’s fuel efficiency. During normal line operation, for every 3,000 hours of flight time or 1,000 cycles, new airplanes will lose approximately 1% efficiency. After a few years of operation, the fuel burn performance of an aircraft will tend to stabilize at between 5 - 7% above baseline new aircraft performance levels. Some aircraft will burn as much as 10% or more in certain circumstances. Major engine overhauls will normally recover approximately ½ of the efficiency degradation compared to a new engine. Engine wash, airframe control rigging, buffing and good paint condition can reduce fuel burn from one to two percent in some cases.
7	EFFICIENT FLIGHT PLANNING EFFICIENT FLIGHT PLANNING An efficient flight planning system should have the full range of Cost Index (CI) planning capability with appropriate vertical and lateral optimization. The vertical and lateral profiles should change with the planned CI because the winds and temperatures vary at different altitudes. Consequently, the final flight levels and route solution would normally differ. For greater accuracy, a flight-planned route should include the planned takeoff runway, the departure and arrival procedures, and landing runway rather than planning from centers of the departure and destination airport. In addition, Cost Index based flight plans should be available for non-Flight Management Computer Systems (FMCS) equipped aircraft. CI optimization is a critical tool for performance optimization and cost control. While many modern larger aircraft are equipped with CI optimization embedded in the FMCS, many regional jet aircraft and other older generation aircraft, do not have the necessary technology. However, CI optimization is available for these aircraft from vendors of Cost Index systems, which operate independently of the FMCS. That technology is available as a software application on Class 1 and Class 2 Electronic Flight Bag (EFB) systems and even as a flip chart or booklet-based system. Compared to fixed-Mach flight planning or Long Range Cruise (LRC) speeds, CI optimization of planned speeds will yield savings from 2 to 3% and in some cases as much as 10% when a flight is restricted to a low altitude or in unusually strong winds.
8	EFFICIENT FLIGHT PLANNING In certain circumstances, on-board CI performance systems, whether embedded in the FMCS or operating on an EFB or in a flip chart, will be of great value for making tactical decisions by flight crews and assist in saving fuel and valuable time, or both.
9	STATISTICAL AND DISCRETIONARY FUEL STATISTICAL AND DISCRETIONARY FUEL One of the difficult tasks for flight dispatchers and pilots during flight planning is to board the correct amount of fuel above the minimum regulatory requirements. Because of the high cost of carrying extra fuel, careful consideration is required to minimize expenses. It is therefore important to develop and maintain up-to-date statistics by aircraft type (from a Fuel Management Information System) on the amount of fuel consumed above the planned fuel burn for each route and aircraft type. Several factors will impact a flight’s fuel burn, including the time of day, day of the week, seasons, runway configuration, training, etc. The idea is to acquire data from which discretionary fuel can be better optimized on a specific route. Used in conjunction with other information such as Airport Traffic Demand charts and graphical traffic display, traffic advisories from ATC units, and weather information, fuel can be optimized accurately resulting in minimum cost and improved safety, because it will also decrease the chances of unplanned diversions.
10	STATISTICAL AND DISCRETIONARY FUEL Experience has demonstrated that without proper statistics, an average of 2 to 3 times the amount of discretionary fuel was carried compared to the amount determined from statistical information. A confidence factor covering 99% of the flights will demonstrate that in most cases, no additional fuel above regulated contingency fuel is required. Flight statistics help increase the flight crew’s confidence level of the flight planning system and will reduce their tendency of ad hoc fuel boarding.
11	ALTERNATE SELECTION ALTERNATE SELECTION One of the most important aspects of fuel optimization is the alternate selection process. With today’s modern aircraft and advanced approach aids at modern airports, diversions are a rare event. The weather requirements for an alternate are very conservative and have not changed in recent years in spite of the significant advances in aircraft navigation and landing systems, improved weather reporting including satellite and radar imaging and improved airport ground systems technology. The primary reasons for diversions are equally divided between medical emergencies, maintenance or weather. Most diversions are not to the planned alternate. There are several reasons why the selection of alternate airports is not fully optimized. Many airlines have not carefully analyzed the best and most efficient alternate for each destination. Many alternate airports are selected because of a dispatcher’s familiarity with that airport or with the services available in case of diversion, or for personal preferences, etc. Many times a long alternate is selected with the full knowledge that if a flight diverts, it will divert to an airport other than the designated alternate airport. As for pilots, they might prefer a specific alternate because of comfort, familiarity, available charts, perceived traffic, ground servicing and communications after landing, etc. When an alternate is carried for regulatory reason such as international flights but the weather and traffic at destination are such that a diversion is very unlikely, the closest suitable alternate (the one that requires the least fuel) should be selected. In some cases, the use of re-dispatch or re-clearance can be used where the alternate can be dropped once the flight is approaching its destination.
12	ALTERNATE SELECTION On longer-range flights, not only is it expensive to carry a long alternate [from a fuel point of view], but payload can also be affected. Every ton of fuel not carried to destination can enable the boarding of additional 10 revenue passengers. As the risk of diversion increases, an important factor to consider when selecting the alternate is customer service and rerouting. Look for an alternate that will offer a quick a turn-around and a rapid return to normal operation, proximity to hotels and restaurants, customs and visa requirements, etc. Airlines should, subject to regulations, establish a clear policy that outlines the actions to take by the crew when the weather at destination or alternate airports deteriorates. The following scenarios could be considered: If the weather at destination is above alternate weather limits and the weather at the designated alternate airport decreases unexpectedly below normal approach limits, the flight can continue at the captain’s discretion after verifying that the landing at destination can be assured and the no unreasonable traffic delays are expected. If the weather at destination is between normal approach and alternate weather limits, the weather at the alternate should remain at least above normal approach limits with no traffic delays expected. If the weather at destination decreases below normal CAT I ILS approach limits, then the weather at the designated alternate should remain above normal alternate limits.
13	ALTERNATE SELECTION Caution is required to ensure that a flight does not end up without options. Unless the landing can be safely assured at either the destination or the alternate airports with no anticipated ATC delays, an enroute landing should be considered. To improve the alternate selection process, consider the following steps: Designate a primary alternate at every destination Perform a detailed review of all possible alternates for each new destination List all the available alternates in order of fuel requirements for reference Ensure that the information regarding handling details, communications, approach charts, etc are readily available for the closest alternates Ascertain that both the crews and dispatchers are fully familiar the primary and closest alternates for each destinations Perform regular reviews to ensure adherence to the established alternate selection process by both pilots and dispatchers.
14	RE-DISPATCH AND RE-CLEARANCE TECHNIQUES RE-DISPATCH AND RE-CLEARANCE TECHNIQUES Re-Dispatch and Re-Clearance procedures offer significant potential savings. However, the Re-Dispatch technique is preferable because ATC clears the flight to destination from the onset and all the necessary fuel requirements are clearly established before flight departure. Re-Clearance, on the other hand, requires the flight to change destination while enroute, which is cumbersome. With accurate flight planning systems, most of the flight planned contingency fuels remain unused and the re-dispatched technique will bring large benefits in both fuel savings and payload optimization especially on long-range flights. Depending on an airline’s fuel policy, between 5 - 10% of contingency fuel is normally boarded. Since flight conditions can vary during flight and possibly the alternate airport is no longer required for arrival, re-dispatching the flight can prevent an enroute stop while carrying maximum payload.
15	Fuel Tankering FUEL TANKERING Fuel tankering should be an integral part of the flight planning system. For ecological reasons, consider tankering only when there is a definite commercial benefit for the airline. Tankering is normally limited to short flights or for tactical reasons. Consider the full cost of carrying the additional fuel, including wear and tear on the aircraft. To avoid overweight landings, the planned landing weights must be monitored. Anticipate the possibility of last minute additional cargo, go-show passengers or changes in aircraft route scheduling. Also consider the departure and arrival runway conditions, the lower enroute altitudes that, in some cases, can limit the cruise altitude options to avoid turbulence or cause additional detouring around weather.
16	WEIGHT MANAGEMENT WEIGHT MANAGEMENT Carrying extra weight on board will result in additional fuel burn equivalent to about 4% per hour of the extra weight carried. This will vary depending on the aircraft type, the flight profile flown, etc. The best way to get an accurate measurement of the penalty associated with the additional weight carried is to compute the flight plan for different weight combinations. Here is a list of items which will result in significant additional fuel consumption when all added up. Old magazines and newspapers Galley containers, ovens, extra supplies Excess duty free material Extra water in the tanks not required for the flight Pillows and blankets Excessive crew baggage Extra airline magazines and publicity in seat pockets Infrequent toilet servicing
17	Weight Management Empty baggage and cargo containers Moisture accumulation in the aircraft insulation Accumulated dirt every where in the aircraft Parts of the aircraft which can be replaced by lighter ones such as carpets, seats, fire extinguishers, tires, etc. Fuel tankering Over fueling Aircraft servicing, caterers, In-Flight service and line maintenance personnel all have an important role to play to minimized excess weight on board aircraft.
18	CENTER OF GRAVITY MANAGEMENT CENTER OF GRAVITY MANAGEMENT An aircraft stability in flight is assured by maintaining the Center of Gravity forward of the Center of Lift. To do so will require that the tail plane produces downward lift which has to be compensated by the main wings. The further forward the Center of Gravity, the greater the downward lift required from the tail plane and the more the main wings have to compensate and therefore the greater the drag. There are obviously limits to the fore and aft loading of an airplane to retain a minimum stability in flight. Depending on the aircraft type, drag created by loading an aircraft to the maximum forward Center of Gravity can increase drag by up to 3% compared to loading the aircraft to the most rearward Center of Gravity where drag can be reduced by approximately 1.5% of nominal drag. Therefore properly managing the Center of Gravity can have a significant impact on fuel efficiency.
19	FLIGHT MANAGEMENT SYSTEM PROGRAMMING FLIGHT MANAGEMENT SYSTEM PROGRAMMING Most modern aircraft are equipped with different sophistication types of Flight Management Systems (FMS). Some will have fuel Cost Index [CI] optimization capabilities and extremely accurate time and fuel predictions. Others will have basic capabilities with no speed or CI optimization. Whatever system is available, crews should make maximum use of the FMS capabilities to monitor the operation and operate the flight as efficiently as possible. Like any computer, the quality of the information entered in the FMS will determine the accuracy of the system’s information and predictions. The present discussion will center on the more advanced FMS in an attempt to make the best use of their capabilities from a crew point of view. At the preflight programming level, the FMS will serve as an excellent means of performing a cross check of the flight plan time and fuel data. While many pilots have different methods of performing fuel checks during flight planning, many limitations exist. Fuel performance charts will only consider data provided by manufacturers and they have many limitations. Items such as aircraft specific airframe and engine in service deterioration, Cost Index, winds and temperatures at specific waypoints, last minute Zero Fuel Weight changes, etc. are not considered. Some crews will use an average burn figure per hour and will do a rough check based on the flight time, etc. The problem is that all the various methods are very approximate and basically are not precise methods of cross checking the accuracy of the flight plan.
20	FLIGHT MANAGEMENT SYSTEM PROGRAMMING Accurate programming of the FMS for long-range flights is critical. For instance, a one-degree deviation in temperature will change the true airspeed by one knot. While that may not seem significant consider the following example. If the average temperature is 10 degrees above or below standard, on a 15 hour flight, it can cover a distance of ± 150 nautical miles and impact the Estimated Arrival Time by as much as ± 20 minutes. Insert the most accurate available information in the FMS. For instance, the departure runway, Standard Instrument Departure with appropriate transition, the planned route with the planned arrival procedure (STAR or FMS) and the planned runway should be inserted during preflight. It is critical to enter the winds and temperatures at each waypoint (ideally these should be downloaded directly from the flight planning system) as well as the altitude step-climbs (or descents) as these will be used by the FMS to further compute additional wind predictions and times. If the FMS optimum altitude predictions are to be used, the winds above and below the planned cruise flight level must also be inserted, as these will be considered when determining if an altitude change is fuel-efficient. The more advanced FMS will also consider the Cost Index selected to determine the optimum altitude. Once all of the available information has been inserted, the fuel and flight times should be accurate and any discrepancies should be reconciled before flight. The minimum Fuel over Destination (FOD), which should include the regulatory final holding fuel (30 or 45 minutes), plus the alternate fuel, should be subtracted from the planned FOD to determine the amount of discretionary fuel for the trip. Improperly programming the FMS may lead to crews wanting to add fuel to compensate for inaccuracies. This can be costly especially on long-range flights where it can impact the payload.
21	FLIGHT MANAGEMENT SYSTEM PROGRAMMING The in-service performance deterioration factor (drag factor) of a specific aircraft should be entered in the FMS for increased accuracy. On long flights, after several hours, more recent winds and temperatures should be updated. When the cruise altitude is different from flight plan, winds and temperatures for the new altitudes should be inserted. Once airborne, the FOD and ETA should be monitored continuously and cross-checked with the flight plan. Any differences should be reconciled. If a high Cost Index was planned for the flight and the FOD falls below the desired level, the CI should be reduced to ensure that adequate fuel is available on arrival. If the flight is held at a less than optimal altitude for some time, allow the FMS to compute the best Mach for that altitude to minimize the fuel burn. If the ETA varies from the normally scheduled arrival time, coordinate with Operations Control and Dispatch to adjust the ETA as discussed in the Mission Management section. The idea is to ensure that the most accurate information is inserted in the FMS to maximize it usefulness, improve safety while reducing cost.
22	AUXILIARY POWER UNIT (APU) MANAGEMENT AUXILIARY POWER UNIT (APU) MANAGEMENT While always keeping the comfort passengers in mind, efficient APU management can yield significant savings. Depending on the aircraft type, the cost of APU usage is about 30 to 50 times more expensive than the gate supplied electrical power. Not only does the APU consume a large amount of fuel and cause pollution, it also incurs high maintenance cost. The APU is often used to compensate for shortcomings in ground operation. Here is a list of reasons that lead to excessive use of APU: Inadequate SOPs; Ground electrical power unavailable; Ground air conditioning or heating unavailable; Shortage of ground personnel to connect the ground support equipment; APU air conditioning provided to unattended airplanes; Aircraft abandoned with the APU running; APU operating overnight; Excessive aircraft towing using the APU; Aircraft plugged to ground electrical but APU still operating; Maintenance performed on the aircraft with the APU instead of ground power;
23	AUXILIARY POWER UNIT (APU) MANAGEMENT Excessive charges for ground equipment or lack of an adequate servicing contract with ground handling agencies often encourages airlines to use the APU; Incompatible or unreliable gate power for certain aircraft types; Crews who have completed their flight leave the aircraft with the APU operating; Unnecessary operation of APU during taxi, takeoff and landing; APU operating in flight with unserviceable generator; and Lack of training and sensitization of personnel. When the APU is required, the load should be minimized by using pneumatics only when necessary. For certain APU types, the fuel consumption is reduced by as much as 35%. If the APU is started when a flight arrives, and if the turn time for the airplane is more than one hour and is left unattended, consider de-powering the aircraft once the passengers have deplaned. Airlines should develop a system to track APU usage and correct any excessive usage.
24	ENGINE START-UP AND TAXI ENGINE START-UP AND TAXI Avoid starting engines at the gate because it will not only increase fuel consumption and pollution but it can also be hazardous for ground personnel. If a departure slot time would result in a long taxi time and if gate occupancy permits, consider delaying the pushback and absorbing some of the delay at the gate with the engine off. To minimize departure delays and ramp congestion, engine start-up and push-back procedures should be streamlined and coordinated. Inefficient procedures at busy airports can delay several other aircraft with engines operating. Once a ramp crew has pushed back an airplane, the ramp crew must disconnect the tow bar and communication cord as soon as possible. To minimize power requirements during initial roll out and minimize ground hazard, position the aircraft in the initial taxi out direction. An engine-out taxi procedure should be considered when: Ramp and taxiway conditions permit The aircraft weight is below maximum landing weight The anticipated taxi time and specific aircraft system permits.
25	ENGINE START-UP AND TAXI If a flight’s weight is light, and the flight crew chooses to taxi with all engines running, the crew may have to ride the brakes. This can cause excessive wear and heating of the brakes. Cold soaked engines might require longer warm up time. Engine out taxi requires slightly more anticipation compared to taxiing with all engines operating. Crews that never use engine out taxi procedures will consider them awkward while crews who consistently use them will consider them routine. Before using engine out procedures, airlines must ensure that the SOPs regarding engine out taxi are well established and crews properly trained. When unanticipated delays are encountered during taxi-out, consider engine out taxi or shutting down engines during extensive delays. On some engine types, the use of engine anti-ice on the ground will result in increased idle RPM and fuel consumption in addition to the possibility of foreign object damage. On slippery taxiways, it might be difficult to stop the aircraft with engines spooled up. Momentarily turning off engine anti-ice will facilitate stopping. In congested ramp areas, delay turning on engine anti-ice to prevent blasting due to spool up. If de-icing is to be performed at a centralized de-icing area and a long deicing is anticipated, consider to shutting engines down during de-icing.
26	ENGINE START-UP AND TAXI Taxi speeds A lot of time can be made up or lost while taxiing. In ideal conditions, the recommended taxi speeds should be around 10 knots for maneuvering and on straight taxiways; however, speeds up to 30 knots are acceptable. Flight crews must remember that fuel burn with engines that are idling on the ground equates approximately 25% of cruise power. Choice of Departure Runway vs. Taxi times At low-density airports, there might be a choice of departure runways. It is always difficult to establish a trade off point regarding the cost of taxiing versus air-time but here is a rule of thumb. Strictly based on fuel consumption, it might be worthwhile to taxi 4 minutes for every minute of air-time saved. For example, a flight departing in a direction 180 degrees from the intended flight course may need to travel an extra 15 miles in the air. This will have to be made up at cruise altitude at the cost of 2 minutes of air-time. In this case, it may be more cost efficient to taxi an extra 6 to 8 minutes. There are other considerations however; if a flight is late with several connections and a short turn around on arrival and if the selection of a different runway can possibly result in additional ground delays, it might be worthwhile to use the most expeditious runway. Crew cost is another factor to consider.
27	REDUCED THRUST TAKE-OFF REDUCED THRUST TAKE-OFF Compared to full thrust, the use of reduced thrust will not reduce fuel consumption during takeoff. However, it will preserve engine life and reduce fuel consumption over time. The majority of engine wear will occur at higher temperatures. For instance, a 1% reduction from full take off thrust will result in a 10% saving in engine life. The first few degrees are the most damaging. Consistent use of reduced thrust will more than double engine life and prevent rapid performance deterioration. Reduced thrust is also important on the first flight of the day when the engine core is cold. When possible, avoid the use of engine anti-icing during takeoff as it will further increase the engine operating temperature (EGT). Avoid using full thrust at the first sign of a slight tail wind. When calculating the required takeoff power, consider the tail wind component. In most cases, it will require a decrease of a few degrees in the assumed temperature and will still permit some reduction from full thrust.
28	INITIAL CLIMB OUT PROFILE MANAGEMENT INITIAL CLIMB OUT PROFILE MANAGEMENT Note: The following departure procedures must be compatible with local noise abatement procedures. Speed and flap management on departure will greatly impact fuel consumption and flight time. Once the flight is airborne, the flaps and slats should be retracted as soon as possible. Although the flaps and slats increase lift, they also increase drag and therefore increase fuel consumption However, when departing in a direction opposite to the desired enroute course, there may be some advantages to maintaining the takeoff flap setting and trading speed for altitude until the aircraft reaches the initial altitude where a turn to the on-course can be initiated. This will minimize the distance away from the intended direction. It will also maintain a lower speed and allow for a faster turn rate to the on-course for a specific bank angle (when possible use bank angles of up to 30 degrees). When the flight is within 90 degrees from the intended course, flight crews should accelerate to normal climb speeds. If a flight is departing away from the intended course, and a turn cannot be initiated before a certain point from the departure course, then cleaning up the flaps and slats will improve departure efficiency. Speed should not be increased above minimum clean drag speed until the aircraft is within 90 degrees from the intended course.
29	LATERAL TRACK MANAGEMENT LATERAL TRACK MANAGEMENT Most efficient flight planning systems will consider all possible routes or portions thereof to determine the most efficient routing between the airport of origin and the destination including the planned departure runway and procedures, winds, temperatures at altitude, airways restrictions, NOTAMS, restricted areas, arrival procedures and expected landing runways, etc. The cost of airways and overflight charges must also be considered. The problem with many flight-planning systems is that the route analysis is based on a fixed Mach number analysis of minimum time tracks. That is very simplistic and the ultimate objective of the system should be to find a minimum cost route based on Cost Index, looking at the route possibilities vertically and laterally. Higher Cost Index values will tend to drive altitude selection to lower Flight Levels due to the higher True Air Speed values, assuming the system is optimizing based on Cost Index and not on simplistic parameters. Failure to monitor overflight charges can result in several thousands of dollars in additional costs.
30	LATERAL TRACK MANAGEMENT Crews should attempt to fly the planned track as closely as possible while taking some short direct routings to minimize large turns at waypoints. It is important to adhere to the general routing of the flight plan. When accepting a long direct routing, there is also the danger of crossing restricted or military areas and when in doubt, it is desirable to adhere to the planned routing. On long flights, there could be some value in reevaluating the routing because after several hours of flying, the wind forecast might have changed. Re-planning and re-filing the route after departure can be difficult for the crews. ATC services will generally not accept changes to the planned route from the ground when a flight is airborne. In some cases, if the actual winds turn out to be different than those forecasted - a rare case in today’s modern flight planning systems with accurate wind and temperature data - there might be some value in re-optimizing the whole flight plan and routing. The use of pre-determined routes and altitude capping should be avoided and the route optimized according to the flight conditions for the day of operation, unless required due to heavy traffic, specific local procedures, or restricted by a preferred ATC route system.
31	VERTICAL PROFILE MANAGEMENT IN CRUISE VERTICAL PROFILE MANAGEMENT IN CRUISE Planning the most efficient vertical profile offers great potential savings. An accurate flight planning system will produce the best vertical profile based on the wind field at each waypoint, the aircraft weight, temperatures and the flight specific Cost Index (assuming the airline is using the correct Cost Index values adapted to its cost structure and the flight planning system incorporates Cost Index values in its altitude selection process). Flight planning systems normally look at all available altitudes to achieve the minimum cost per ground mile. A properly optimized flight plan will provide the best altitude profile to be flown for the current mission conditions. This may include descents to lower altitudes to take advantage of better wind / TAS combinations. In the case of a flight being forced to deviate from its flight planned altitude profile, the wind values for the next usable flight levels above and below the planned altitudes should be available to assist the crew in making tactical decisions. If forced away from the planned altitudes, crews should attempt to return to the flight planned vertical profile as soon as the restrictions are cancelled.
32	VERTICAL PROFILE MANAGEMENT IN CRUISE Use FMS suggested optimum altitudes with care. Unless the wind field (including winds above and below planned altitudes) and temperatures at the planned waypoints are accurately inserted into the FMS by either an automatic download or manually, the recommended FMS optimum altitude will be incorrect. Some older FMS versions will recommend a flight level based on weight regardless of winds or Cost Index. In the case of older generation or regional aircraft without FMS altitude information available, the Aircraft Operating Manuals simply recommend altitudes normally based on weight for LRC speeds (no wind or Cost Index input). Performance advisory systems are available for non-FMS aircraft, which enable the use of Cost Index speeds and altitude optimization. These systems are available in either in a booklet format, electronically as part of the Electronic Flight Bag system (EFB), or in a stand-alone system. Ideally, the optimization from these systems should be integrated to the flight planning system for greater flight planning accuracy and optimization. Cost Index optimization will result in substantial fuel and time savings, while balancing the time and fuel costs for a specific airline cost structure. They would also permit the use of tactical Cost Indices for day-to-day operation to accelerate flights when adverse winds are impacting on the on-time performance or during delays when several passenger connections are affected. The use of lower Cost Index values should also be available to reduce speed for flights arriving early thereby reducing fuel consumption and minimizing the chances of gate holds and possibly ramp congestion.
33	VERTICAL PROFILE MANAGEMENT IN CRUISE If a flight is restricted to a lower than planned altitude for a significant time period such as ocean crossings, allow the Cost Index to determine the best Mach for that altitude. This process may result in additional time costs; however, there will be significant fuel savings. In some extreme cases, it might even allow for the completion of the flight rather than diverting for fuel. If the actual aircraft weight differs significantly from the flight-planned weight, the best option is to re-compute the flight plan to achieve a better optimized vertical flight profile. On short flights, the most efficient vertical profile would be to continue climbing until intercepting the descent profile. However, this is not always practical. Most optimum altitude data for short flights will assume a minimum cruise time of 5 minutes. Total air distance should be considered when selecting the optimum altitude on short flights, including the departure and arrival runways and procedures.
34	CRUISE SPEED MANAGEMENT CRUISE SPEED MANAGEMENT In normal cruise conditions, FMS equipped aircraft should produce an optimized Mach number based on the selected Cost Index, the aircraft weight, altitude, temperature and wind conditions. The Cost Index should not be changed to control the Mach number. As the winds, weights and FL change, regardless of how well they match the flight plan, allow the FMS to compute the best Mach number. The above assumes that the Cost Index selected is properly optimized for a specific airline’s cost structure. Manually overriding the FMS speed will normally result in a loss of efficiency either in time, fuel or both. Several aircraft types do not have FMS speed optimization. In this case, either a fixed Mach speed or Long Range Cruise (LRC) speed is typically used. LRC speed is equivalent to 99% of the Maximum Range Cruise (MRC) fuel burn but it does not account for the wind effect. Again, there are optimization systems, paper or electronic, which provide an optimized Mach and improve the cruise efficiency from about 3 to 7% depending on flight conditions and altitude.
35	CRUISE SPEED MANAGEMENT The Cost Index selected for a flight should be based on actual airline cost structure. It should also be route specific since the price of fuel will often vary at each origin airport. However, the use of “non standard” Cost Index values can be used if the flight conditions for that day are different than the average. Higher head winds, last minute delays, curfews, slot times, gate constraints, down-line impact of on subsequent flight, etc. can increase a delay costs and the use of higher than normal Cost Index can be utilized to minimize the delay cost. On the other hand, for an early arrival situation, a lower than “standard” Cost Index can be used to reduce the speed of an early flight. This will save fuel and prevent possible gate holds, ramp congestion, and additional ground staff costs. While the cost of fuel should be minimized, other costs must be considered when selecting a specific mission Cost Index. Post departure re-optimization of the flight speed profile should be considered to reduce other time related costs.
36	COST INDEX MANAGEMENT COST INDEX MANAGEMENT Cost Index is the ratio of the cost of time over the cost of fuel. When entered into the FMS, it optimizes the flight profile to balance the cost of time (crews, aircraft time based maintenance, etc) against the cost of fuel. For instance, if time is not a factor (Cost Index= “0”), the use of cost index 0 would optimize the flight for minimum fuel burn taking into consideration the aircraft weight, altitude, temperature and wind conditions. If time is critical and the flight must be conducted at minimum time, then Cost Index 999 (or the maximum for a particular aircraft type) would yield the minimum time flight but at the expense of significant increase in fuel consumption. Note carefully that in an optimal system that is not simply a case of “going fast”. Rather, it is a complex optimization of the winds at different flight levels with the TAS values at those levels (and if in the flight planning system, also considers the routes) to produce a true minimum flight time scenario, but at a minimum possible burn for that flight time. That is why Cost Index is used - the result is an optimal solution; minimum possible burn for the flight time, or minimum flight time for the burn. Cost Index “0” should seldom be used because cost of time is usually a factor. A tactical exception would be an in-flight delay, such as a hold. In that case, use of Cost Index zero (or even slower) will be appropriate. Cost Index values at the maximum limit are also used less frequently, however, if circumstances support the cost of the fuel, then it is worth the extra fuel burn for the flight time savings.
37	COST INDEX MANAGEMENT Airline that maximize the use of Cost Index will conduct a study of all time related costs and determine the best default Cost Index for day-to-day operation. Since the cost of fuel differs from airport to airport, the default Cost Index should be route specific. Because the flight schedule will subsequently have an impact on the speed at which flights are operated on the day of flight, the scheduled flight times should be based on speeds derived from the route specific default Cost Index. It is very important that airlines spend the time and effort to properly determine the most cost efficient value to minimize overall cost. There are, however, other time related costs that occur during the day-to-day operation that would justify not using default Cost Index. Stronger than usual headwinds or a last minute delay can affect several connecting passengers, impact subsequent flights with short turn around times, miss a curfew or a slot time, create gate occupancy conflicts, crew legalities or connections. As can be seen, the cost of time can vary and the use of other than default Cost Index values will help minimize the time related costs even though additional fuel could be consumed in the process. Flight crews are normally in a difficult position to decide on the most appropriate Cost Index for the flight. Flight dispatch or Operations Control must proactively plan and monitor of the flight progress. Finally, whatever airlines decide to do, they must ensure that all processes are well defined, managed and fully integrated. Furthermore, the value of effective training cannot be overemphasized. These processes can be somewhat counterintuitive and compliance will be somewhat proportional to understanding. The benefits of a well thought out performance optimization program are significant.
38	FMS DESCENT PROFILE MANAGEMENT FMS DESCENT PROFILE MANAGEMENT A properly planned and executed descent offers the greatest opportunity for fuel savings. The ideal profile is an uninterrupted descent from cruise altitude without the use of thrust or speed brakes until reaching the final approach stabilization altitude. Adhere as closely as possible to the computed descent speeds and monitor the decent profile to determine as early as possible if adjustments are required. If above profile, correct by increasing speed rather than using speed brakes. If below profile, correct by reducing descent speed slightly to regain profile or make power adjustments for profile correction as high as possible.
39	FMS DESCENT PROFILE MANAGEMENT FMS Descent Profile FMS systems can compute accurate and efficient descent profiles. Except for tactical reasons, do not intervene by descending early or late, or otherwise by modifying speeds and descent rates. In the final approach area, avoid taking flaps early and use the minimum drag speeds when conditions permit. The need to intervene may be necessary in certain situations but unless the profile is modified by ATC, it should be flown as planned. When possible, allow the technology to do what it was designed to accomplish. To be accurate and efficient, the FMS should be allowed to manage the descent profile, The number one rule in programming the FMS is to enter the approximate descent and approach pattern which will most likely to be flown, especially the first altitude restriction to be met. Otherwise, the top of descent point computed by the FMS profile will be erroneous and the aircraft’s energy state in the terminal area will be incorrect. Energy management is of the utmost importance during the descent profile and the approach. Failure to properly program the FMS will undermine the crew’s confidence in the system and may lead to a destabilized approach by placing the aircraft too high on close final. Monitoring the previous traffic clearances may provide some clues to the restrictions that can be anticipated.
40	FMS DESCENT PROFILE MANAGEMENT FMS Descent Profile FMS systems can compute accurate and efficient descent profiles. Except for tactical reasons, do not intervene by descending early or late, or otherwise by modifying speeds and descent rates. In the final approach area, avoid taking flaps early and use the minimum drag speeds when conditions permit. The need to intervene may be necessary in certain situations but unless the profile is modified by ATC, it should be flown as planned. When possible, allow the technology to do what it was designed to accomplish. To be accurate and efficient, the FMS should be allowed to manage the descent profile, The number one rule in programming the FMS is to enter the approximate descent and approach pattern which will most likely to be flown, especially the first altitude restriction to be met. Otherwise, the top of descent point computed by the FMS profile will be erroneous and the aircraft’s energy state in the terminal area will be incorrect. Energy management is of the utmost importance during the descent profile and the approach. Failure to properly program the FMS will undermine the crew’s confidence in the system and may lead to a destabilized approach by placing the aircraft too high on close final. Monitoring the previous traffic clearances may provide some clues to the restrictions that can be anticipated.
41	FMS DESCENT PROFILE MANAGEMENT Distance, speed and altitude trade off Generally, the following rules can be used for a quick calculation between distance, speed and altitude trade-off: An aircraft in clean configuration and at idle power will decelerate 10 knots per nautical mile when in level flight. i.e. 60 knots speed loss will require about 6 NM In a clean configuration and at idle power, an aircraft will descend 1,000 feet per 3 NM A flight that has decelerated 60 knots when in level flight and subsequently regains initial speed will lose 2,000 feet (1,000 feet per 30 knots) during acceleration to previous speed. For example, flights arriving downwind from the landing runway could most likely receive an altitude restriction to cross downwind from the airport at about 6,000 feet. If any kind of tailwind exists on the downwind leg or if a Visual Approach is expected, the flight, from an energy standpoint flying at 6,000 feet and at 250 knots, for certain aircraft types (B767, A320) would be high on the profile and need extra drag to complete the approach.
42	FMS DESCENT PROFILE MANAGEMENT If the speed abeam the airport while at 6,000 feet is reduced to 190 knots instead of 250 knots, the aircraft’s energy level would be equivalent to that of crossing the abeam point at 250 knots but at 4,000 feet. At 190 knots, 9 NM would be required to descend from 6,000 feet to 3,000 feet and this would place the aircraft in a good position for an energy efficient approach when turning on final. Otherwise, the need to reduce speed from 250 knots to 190 knots and descend at the same time would make the aircraft too energy rich and would require the use of speed brakes. Closely monitor the energy level of the flight and make the appropriate adjustments to avoid continuous alternating use of thrust and speed brakes during descent and approach.
43	FMS DESCENT PROFILE MANAGEMENT Descent Profile Wind Corrections A clear understanding of the FMS Vertical Navigation (VNAV) capabilities will permit the crews to establish a much improved descent profile. For a more accurate FMS computation of the descent profile, insert the descent winds. If the descent winds are not entered in the FMS, a wind profile will be built assuming a constant decreasing wind speed from the cruise level down to the airport altitude. On some aircraft, the computed descent winds at each waypoint can be seen on the flight plan page and can be compared to the forecast winds. If they are found to be significantly different, then the forecasted winds should be updated in the FMS. Chances are that the descent winds will vary from the assumed wind profile built by the FMS. If the winds are noticeably different than those computed by the FMS, like in the case of a jet stream or increasing winds after the descent is initiated, the pilot can, re-select the Direct To function to the active waypoint after the winds stabilize. This allows the FMS to recalculate a new wind profile and descent vertical flight path using actual winds from the present altitude and will create a new possibly more accurate descent profile. It is important to take corrective action as high as possible to allow sufficient time for the extra energy to be burnt off with additional speed in case of an increasing tailwind or to regain the proper profile as high as possible with increased thrust when in an increasing headwind.
44	FMS DESCENT PROFILE MANAGEMENT Landing Weight Higher landing weights will increase the descent distance for the same descent speed since it takes longer to dissipate greater potential energy. However, if the descent speed is increased, then the additional energy will be absorbed by the increased drag and the descent angle will then be increased. For instance, competition gliders will carry water ballast to increase speed while maintaining the best angle of attack. Some modern FMS systems will vary the descent speed in accordance with landing weight. Other optimization systems will account for the landing weight while computing the descent profile.
45	FMS DESCENT PROFILE MANAGEMENT Engine Anti-Ice On some aircraft types (Airbus 330, Boeing 767, etc.), the engines will automatically spool up upon selection of engine anti-ice. In some cases, this can force the aircraft above the computed descent profile as the increased speeds might not be sufficient to absorb the extra energy. When engine icing is anticipated, for the aircraft which do not account for the use of engine ice on descent, plan a lower than desired descent speed in the FMS for profile computation purposes. The increased speed resulting from the use of engine anti-ice will bring the descent speed closer to the desired descent speed. If the flight is on profile when the engine anti-ice is selected, attempt to increase speed rather than using speed brakes to absorb the extra energy.
46	FMS DESCENT PROFILE MANAGEMENT ATC Restrictions When on descent profile, if the descent is interrupted temporarily forcing the aircraft above profile, slow down as much as possible while in level flight and then trade the surplus altitude to subsequently regain the descent speed and profile. This minimizes the chances of subsequent use of speed brakes. This could be subject to ATC restrictions depending on circumstances.
47	FMS DESCENT PROFILE MANAGEMENT Penalties for Early/Late Descent Profiles that commence too early or too late cause a significant increase in fuel usage. f one is to err, it is better to be slightly early on descent, rather than late. If one starts down early, the opportunity of regaining the optimum profile is available and it should be done as high as possible. If the descent is started too late, then the fuel has already been consumed by remaining at altitude and it can never be recovered since the extra energy must now be dissipated with increased drag. Ideally, the descent profile should be planned correctly. Some crews tend to always undershoot target altitudes for comfort. Appropriate programming of the Flight Management Systems should enable the aircraft to accurately be on profile. Note: There is obviously a greater use of speed brakes for crews who are new on an aircraft type or have less experience on heavy jets but speed brakes should not be a substitute for adequate descent profile management and overall planning. The goal is to reach the initial approach point at the right altitude and the correct speed without the use of speed brakes or power. Ideally, the descent should be uninterrupted.
48	BASIC PRINCIPLES OF THE DECELERATED APPROACH BASIC PRINCIPLES OF THE DECELERATED APPROACH The most fuel-efficient arrival allows the descent profile to flow unrestricted into final approach without the use of engines thrust or speed brakes. The following should be considered: Since normally the descent speed below 10,000 feet is limited to 250 kts, that speed should be maintained until ready to reduce speed to the minimum drag clean speed in preparation for the approach phase. When feasible, use or request speed vectors to prevent excessive distance travel to establish the aircraft on final approach. This will often require some initiative by the crew. Remember that most aircraft have a significant speed margin of almost 150 knots between VMO and clean maneuvering speed during the descent phase. Keep the aircraft clean! Flaps and slats are not designed as drag devices for slowing down but to produce lift. In the process, there is a significant drag increase. Continuous extension of flap at near limiting speeds also increases the risk of component failure. Note that ATC might not always be aware of the clean maneuvering speed for your aircraft type. Often a word to them will save an unnecessary early flap extension. Don’t be afraid to retract the flaps should the approach be extended
49	BASIC PRINCIPLES OF THE DECELERATED APPROACH Request the arrival sequence number from the Approach Controller on initial contact. This makes it easier to estimate the distance to touch down. Decide how to manage the energy and whether to slow down early to minimum drag speed to prevent excessive downwind vectoring. Avoid dumping excess altitude too early or use of speed brakes to a cleared altitude and then having to add power to fly level at that cleared altitude for an extended period of time Unless assigned a hard speed by ATC or by a specific procedure, do not hesitate to use speed control to best advantage
50	BASIC PRINCIPLES OF THE DECELERATED APPROACH FMS Arrivals Many airports use FMS arrivals. A well-designed FMS arrival should allow a flight to descend and maneuver with the engines at idle and the engines ‘spooling-up’ at the final approach fix, thus saving fuel. Visual Approaches Although ATC expects the FMS arrival to be flown as planned, it is sometimes possible to perform a Visual Approach from the downwind leg. A Visual Approach will save some additional fuel. Calculations indicate that in some cases, fuel savings associated with Visual Approaches equal a total of 2 minutes at idle power fuel flow (20 kg for the A320/B737). The distance traveled is reduced by approximately 3 miles for each of the downwind and final approach. The aircraft is assumed to roll out on final approach at approximately 2 miles back from the FAF when conducting a Visual Approach. The Visual Approach offers an opportunity to best optimize all of the above recommendations. During FMS approaches, which are designed for IFR conditions, the use of a Visual Approach will normally result in additional savings.
51	BASIC PRINCIPLES OF THE DECELERATED APPROACH Decelerated Approaches (Low Noise Low Drag) Although this is an Airbus recommended procedure, it applies to most aircraft types. The Low Noise/Low Drag approach has been used to minimize noise in several countries for many years. The basic principles apply to other aircraft types with minor variations depending on specific characteristics. The advantages of the Decelerated Approach are as follows: Lower fuel consumption and emissions Lower noise levels Time savings Flexibility and ability to vary speed to suit ATC Another advantage of using the Decelerated Approach is that it sets some clearly defined target altitudes and speeds to achieve during the approach. After a few approaches, it will result in improved standards because most approaches at various airports will be completed in an identical manner. Presently, many crews will start flap selection at a distance that varies from over 20 miles to less than 5 miles from touchdown with little consistency from one approach to another.
52	BASIC PRINCIPLES OF THE DECELERATED APPROACH In the case of the Decelerated Approach, the slats and flaps selections are mainly a function of altitude above the ground rather than a distance to the touch down point. This permits improved energy management during the approach. Using the Final Approach Fix (FAF) to establish the stabilization altitude will lead to inconsistencies as the FAF can be located at a distance which can vary greatly from the runway threshold. Basically, the aircraft is kept in a clean configuration with the speed reducing to minimum drag clean speed until base leg or prior to turning final at approximately 3,000 feet above ground. At that point, the initial slat selection is made and the speed adjusted to the slats only minimum drag speed. If the aircraft intercepts the glide slope above 3,000 feet, slats/flaps selections should be delayed until reaching that target altitude. The ability to maintain speed on the glide slope in a clean configuration will depend on the aircraft type, the landing weight and the wind component. If possible, use speed brakes to control speed rather than flap or gear extension to control speed.
53	BASIC PRINCIPLES OF THE DECELERATED APPROACH
54	BASIC PRINCIPLES OF THE DECELERATED APPROACH The next target is 2,000 feet AGL where the initial trailing flaps are selected (approximately 15 degrees depending on the aircraft type). This normally occurs just outside the Final Approach Fix and a gradual reduction toward the final approach speed is started. When the flaps have reached their intermediate position, the landing gear is lowered. The final landing flap selection is made to achieve approach stabilization by 1,000 feet AGL. Note that the flight should be configured at the approach speed by 1,000 feet AGL. If by 500 AGL, the flight is not fully stabilized, a Go-Around should be considered. Flight crews will quickly become familiar with the Decelerated Approach and significant fuel savings will result.
55	BASIC PRINCIPLES OF THE DECELERATED APPROACH High Head Winds on Final will result in long final legs When high winds (30 knots or more) are encountered on final approach, its effect on the intermediate approach pattern can be significant. Slower traffic will often cause the subsequent traffic to back up and will result in very long final approach legs at low speed in a high drag configuration. When this is anticipated, subject to ATC restrictions, the crew should attempt slow down as soon as the situation is recognized (normally early downwind). All speeds above minimum drag clean speed should be traded for altitude even if that will make the flight appear high on final. The flight will likely end up on a long approach and the extra altitude can be used up once the flight is turned toward final. It is not difficult to eliminate excess altitude on final approach when headwinds winds are strong. The idea is to reduce speed early, when possible, to minimize excessive downwind travel and getting into a high drag configuration while on the final approach in a strong headwind. This is extremely inefficient and will consume a significant amount of fuel during the final leg. Slowing down early will improve the possibilities of maintaining the aircraft in a clean configuration as long as possible once on final. At this point, the previous traffic would have had time to move forward. This should help position the flight for a low drag approach, which is even more critical in a high head wind situation.
56	REDUCED FLAP LANDING REDUCED FLAP LANDING Most airplanes are certified to land without using full landing flaps. Some aircraft types even have auto-land capability while using reduced flap settings. When conditions are appropriate, landing at less than full flap has some definite advantages. At the last flap setting more drag than lift is normally generated. Reduced flap landings will not only reduce fuel consumption but also decrease chemical and noise emissions. When landing an airplane with reduced flaps, fuel burn is reduced by approximately 25 kg in fuel on an A320/B737 landing and 50 kg for an A340/B777 size aircraft. Some of the factors to consider when performing a reduced flap landing include: The landing weight; The runway length; The runway exit point and occupancy time; The runway surface conditions; Possible tail wind component on final approach; and Brake cooling during short turn around times
57	REDUCED FLAP LANDING The average increase in speed for reduced flap is landing is approximately 5 knots and the extra landing distance around 500 feet. Several airlines have made reduced flap landing procedures a standard.
58	IDLE ENGINE REVERSE ON LANDING IDLE ENGINE REVERSE ON LANDING With the ever increasing price of fuel and environmental considerations, the use of idle engine reverse should be used whenever possible. The main advantages of using idle reverse on landing include: Reduction in fuel consumption; Reduction in environment emissions; Reduction in noise emissions; Better passenger comfort; Elimination of a high power cycle on the engines; Reduction of foreign object damage (FOD); Reduction in potential engine stall and re-ingestion; Increased engine reliability; Lower cooling time requirement before shutting engines down for engine-out taxi; and Slower engine performance deterioration.
59	IDLE ENGINE REVERSE ON LANDING Most modern aircraft now use carbon brakes. Brake wear is more a function of the number of applications rather than the amount of braking used. Carbon brakes can withstand higher temperatures without loss of efficiency or fading. In the case of an airplane equipped with auto-brake capability, the braking selection will determine the rate of deceleration, and the stopping distance is generally identical to landing with full reverse thrust. When using idle reverse on landing, the following factors should be considered: Runway length and aircraft landing weight; Tailwind on final approach; Runway surface condition; Touch down point; and Turn around time. On long runways, idle reverse thrust can decelerate the aircraft sufficiently without using the brakes.
60	ENGINE-OUT TAXI-IN ENGINE-OUT TAXI-IN Under normal conditions, engine-out taxi-in should be a standard procedure. SOPs that are well designed encourage engine-out taxi with minimal work for the flight crew. When using the engine-out taxi procedure, anticipation is important and the aircraft must be kept moving. Flight crews will require training and familiarization with engine-out taxi procedures. Crews familiar with engine-out taxi-in procedures follow the procedure after almost every landing. The main advantages are the following: Reduction in fuel consumption; Reduction in pollution; and Reduction in brake wear. Consider the following before apply engine-out taxi-in procedures: Taxiway surface conditions; Taxi-in time; Ramp congestion; and Local airport regulations.
61	FLIGHT SCHEDULE AND FUEL MANAGEMENT FLIGHT SCHEDULE AND FUEL MANAGEMENT Based on an accurate airline cost structure, an optimized schedule takes into account efficient aircraft speeds. Airlines must use rationale business-based methodologies for establishing optimized Cost Index values (CI) for each aircraft type equipped with Flight Management Systems (FMS) or with other onboard systems capable of CI optimization. The CI should reflect a balance between the fuel cost and other time-based costs specific for the airline and, when the business processes support it, the specific flight based costs. Since the price of fuel is normally different at each departure airport, the specific flight CI should reflect the price differential. Cost Index is a function of time cost over fuel cost. Flying with a high CI will increase aircraft speeds and may result in flying at lower altitudes, depending on conditions. The increased fuel costs are offset by a reduction flight time related costs. A low CI increases the flight time costs, and results in flying at higher altitudes, however it consumes less fuel.
62	FLIGHT SCHEDULE AND FUEL MANAGEMENT For example, a B767 using a very high CI (inappropriately high for the actual corporate time costs in this example) on a 6-hour flight might result in the flight burning 3 tons of additional fuel (US$1500) relative to a flight plan at the correct Cost Index. The time saved at the high Cost Index could be, for this example, 20 minutes flight time worth US$1,000 (1/3 of $3,000 / hour time cost for rental, maintenance, crew, etc.). It would result in a US$500 loss for that flight due to the high cost of fuel compared to value of extra time saved. Using a much-reduced CI, (compared to the hypothetically correct for the airline’s actual cost structure), the operator could reduce the fuel burn by $1,000 but increase the flight time by 15 minutes ($750) thereby reducing the total flight cost by $250. One might want to consider the fact that additional fuel burn in some cases might be cost effective when dealing with of late or oversked flights with numerous connections, curfew or slot restrictions, and impact of the delay on subsequent flights, etc.
63	CALCULATION OF SAVINGS CALCULATION OF SAVINGS Air Traffic Control The impact of Air Traffic Control on fuel consumption is covered elsewhere. However the following can have a marked effect on fuel consumption: •Excessive Government regulations; •Poor ATC route structure; •Excessive ATC restrictions for no specific reason or for ATC controllers’ convenience; •Lack of sufficient ATC staffing; •Poor equipment; •Inflexible noise abatement procedures; and •Inadequate communications.
64	CALCULATION OF SAVINGS Pilot Technique Through analysis of Fuel Management Information systems, which accurately captures achieved flight performance, it can be demonstrated that the fuel performance of various crews can vary on average from plus or minus 2.5% from planned fuel burns. This can be even more pronounced on short-range flights where a significant portion of the flight is spent maneuvering. Proper training, emphasis on fuel economy, adequate SOPs, proper management leadership and accountability will greatly impact fuel performance. It may be possible to save at least 1% to 2% in fuel consumption if the crews consistently apply all the following fuel saving procedures: •APU management; •Efficient start up and taxi speeds; •Engine-out taxi out; •Departure runway selection if possible; •Speed control and altitude trade off on departure; •Post departure flight profile optimization; •Cruise altitude and speed management process; •Descent profile planning and management; •Low noise low drag approaches procedures; •Reduced flap landing; •Idle engine reverse on landing; •Engine-out taxi in.
65	CALCULATION OF SAVINGS Cost Index Flying Cost Index optimization should be the basis for the optimization of all airline flight operations. The reason is simple; optimal profiles burn the least amount of fuel for a given flight time or, conversely, they have the shortest flight time for a given amount of fuel burn. The best way to plan and fly “optimal” profiles is to use a Cost Index optimization system, both at the flight planning stage and for real time flight management in the cockpit. Airlines that make proper use of Cost Index optimization at the flight planning stage, and on a day-of-flight basis, will achieve the greatest savings. With any optimization system, the system optimizes to a target parameter; in this case, the Cost Index. So, it is obvious that the Cost Index, which is a ratio of the true time cost per minute to the actual fuel cost, must be selected correctly. Since fuel costs, and in some cases, time costs vary with the route, the Cost Index should be route specific. Once an airline has made the internal effort to analyze their incremental time costs, then the Cost Index for each route should be the basis for their schedule construction and day-to-day operations. The potential savings from Cost Index flying vary based on many factors. However, total overall cost savings of approximately 3% - 5% is not unrealistic, especially given current very high fuel costs and the fact that most non-Cost Index flight profiles are rather aggressive and not particularly fuel conservative.
66	CALCULATION OF SAVINGS When circumstances in the day-to-day operation would result in a flight arriving significantly later than scheduled, (to the point where connections, curfews, etc. would be jeopardized) then it may be appropriate to use a higher Cost Index value to achieve a required target arrival time to minimize these costs. It will result in significant additional savings. The importance of using Cost Index to achieve these accelerated profiles, rather than just “going fast”, is again related to the fact that these profiles are optimal. This results in the achieved flight time being the shortest, and the least amount of fuel-burn the least possible using Cost Index. In the case of misconnection related costs, these can be very significant and in many cases, can be mitigated by the proper use of accelerated Cost Index profiles. No other method of flying - including fixed Mach, multiple fixed Mach, Long-Range Cruise - will result in optimal profile solutions. Furthermore, these basic profiles also use simplistic altitude selection methods. However, altitude is a critical component of the profile. Cost Index solutions solve both the altitude and Mach number. By using Cost Index profiles significant cost savings will result because of a more efficient overall operation, based on both fuel and time based savings.
67	CALCULATION OF SAVINGS Accurate Flight Planning Airlines can save millions of dollars with the right guidance on cost management, an accurate flight planning system, and properly trained dispatchers. Optimizing each flight and avoiding pre-determined routes or unnecessary altitude capping will save a significant amount of fuel. An adequate flight planning system will: •Optimize the route laterally, •Vertically based on Cost Index, •Look at the enroute navigation fees, ETA (connections) •Will assess all possible combinations to come up with the minimum cost (fuel and time) for a specific flight. Savings in excess on 1% to 2% are not unreasonable.
68	CALCULATION OF SAVINGS Using Statistics for Fuel Optimization Fuel in excess of minimum regulations should be planned carefully. The availability of statistics on the additional fuel consumed above the flight plan burn on a specific city pair based on time of day, day of the week, season, etc will yield valuable information to both the dispatchers and crews. The information will help them determine the right amount of fuel for the flight. In general, crews are in a difficult position to assess the correct amount of fuel required for a flight because of a lack of information on the actual traffic, the available time to flight plan, aircraft turn around times, ATS special advisories, frequency of flying that route, wanting comfort fuel, and lack of adequate statistics, etc. Almost invariably, the fuel added by crews without coordination with the dispatcher remains unused. Boarding additional fuel based on adequate statistics will reduce fuel burn from 0.5% to 1%. Alternate Selection Diversions for modern aircraft flying to airports with sophisticated ground equipment are a rare occurrence. On average, diversions will occur about one in a thousand flights. Normally, most of the diversions are not weather related but are about one third for mechanical reasons, one third for medical reasons and the rest for weather. Most of the weather related diversions were most likely anticipated based on the forecast.
69	CALCULATION OF SAVINGS It is therefore important to select the most efficient alternate based on circumstances. This is assuming that a no-alternate IFR flight is not possible. Many factors can affect the alternate selection. Airlines should systematically review the availability of the closest alternate for each destination. If the chance of diversion is very small, then select the closest alternate based on realistic distance to travel as per the anticipated ATC routing. When the chance of diversion increases, a more appropriate alternate should be planned taking into consideration all factors that can minimize the impact on the operation (see the alternate selection chapter for more details). An efficient alternate selection process can yield savings of 0.5% to1% in fuel not considering its impact on payload and other costs. Aircraft Fuel Burn Management As aircraft are put into operation, each airplane develops its own burn characteristics. If we compare a new airplane to one which is the same model and that has been in operation for a few years, you may see a difference in the fuel burn in excess of 5%. Accurately tracking each aircraft and adjusting flight plan fuel burns will reduce the carriage of unnecessary fuel. This is particularly critical for long-range airplanes. The failure to properly manage specific aircraft fuel burns will lead flight crews to develop their own system and add fuel on just about every flight. This lack of confidence in the planning system will be very costly and can lead to an increase fuel cost in the order of 0.5% to 1%. Tankering Depending on circumstances, the potential savings from tankering will vary between airlines. An adequate tankering process will yield significant savings. Proper fuel supply management will prevent tactical tankering, which is normally costly (see the Tankering section for more details). An efficient tankering program should save airlines between 0.5% to 1% and more in fuel cost.
70	CALCULATION OF SAVINGS Zero Fuel Weight Management Proper estimation of the Zero Fuel weight is critical because it will decrease the carriage of unnecessary fuel or prevent a possible last minute delay for additional fuel. It will also have a significant impact on the flight profile. Again, poor EZFW predictions will undermine the confidence in the flight planning system and lead to the tendency to load additional fuel to compensate for inaccuracies. Savings in the order of 0.5% to 1% are possible. Center of Gravity Management Flying with an aircraft loaded to the most forward Center of Gravity will consume approximately 3% more fuel above baseline Center of Gravity loading while flying with the most rearward Center of Gravity will reduce fuel consumption by as much as 1.5% depending on the aircraft type. Overall, properly managing the Center of Gravity will easily yield saving in the order of 1% to 2% during line operation. Maintenance Aircraft maintenance impacts the efficiency of an aircraft. Engine washes, flight control rigging, airframe buffing, paint condition, engine overhaul, door seals, protruding controls, spoilers, doors, etc contribute to the reduction of an airplane’s fuel efficiency. With improved maintenance, approximately 1% – 2 % in fuel savings can be realized. Refer to section 10 for more details.