gga - cost index

7/31/2019 GGA - Cost Index

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1/24Dispatcher Transition Course Cost Index

IN-FLIGHT PERFORMANCE

Cost Index

Version 1.4


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Content

Cost Index2

Specific Range1


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Content

Cost Index2

Specific Range1


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1. Specific Range

SR variations with Mach number

SR: distance coveredper fuel mass unit burnt

SR reaches a maximum

at the MACH of MAXI-RANGE (MMR)

At the Mach of Maxi-Range, the

fuel consumption is minimumas regards to the distance crossed

at the given altitude and weight.

SR (NM/t)

40

50

60

70

Given :- Altitude- Weight

MMR

Maxi Range

Mach.76 .80 .84


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1. Specific Range

SR variations with Mach number

M < MMR SR

For a given fuel quantity, thecovered distance is lower.

For a given distance,

consumption is higher.

M < MMR time

MMR = Inferior limit

SR (NM/t)

40

50

60

70

Mach

Maxi Range

.76 .80 .84


MMR


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1. Specific Range

MMR: advantages and drawbacks

Very advantageous regarding the trip fuel

But MMR is too low Trip time is quite long

Solution

Increasing cruise speed without increasing too muchthe fuel consumption This is what Long Range Cruise Mach aims at


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1. Specific Range

Long Range Cruise Mach

Definition:

SR: distance covered

per fuel mass unit burnt

Flying at LRC Machenables a low fuelconsumption (but

NOT minimum), whilethe speed is higherthan MMR

SRLRC = 99 % SRMAX

Mach

SR

.76 .80 .84

MMR

LRCMax SR

-1%






1. Specific Range

Long Range Cruise Mach

Advantages of LRC onMMR:

The 1% fuel consumptionincrement is compensated

by an important gain onspeed and consequently onflight time.

Any selected Mach number

under LRC would result in adecrease in the fuelconsumption.

Mach

SR

.76 .80 .84

LRC

MMR




Givenaltitude

A330FL 350

ISA

Example :

Max SR = 68.44 NM/tMMR = M 0.796

99% of Max SR = 67.75 NM/tLRC = M 0.811 + 9 kt TAS



Content

Cost Index2

Specific Range1



2. Cost Index

Direct Operating Costs: D.O.C.

Do not take as a reference

Cyclic

Maintenance

7%

Cockpit crew

13%

Hourly

Maintenance6%

Insurance

2%

Cabin crew13%

Fuel

15%

Depreciation

27%

Financial

charges

17%

Example of Direct Operating Costs



2. Cost Index


D.O.C. are made of:

Fixed costs Flight time related

costs

Fuel consumptionrelated costs

ECONOMY=

Minimize D.O.C.

Lower fuelconsumption

Lowerflight time

Compromise Time / Fuel ...

And

/ Or



2. Cost Index


Fixed costs: CC

Aircraft ownership (depreciation, lease rentals unrelated toflight hours, insurance) ($)

Cyclic maintenance ($)

Fixed flight crew ($)

Fixed cabin crew ($)



2. Cost Index


Time-related costs: CT . T

CT : Time related costs per flight hour:- Hourly maintenance costs ($/h)

- Airport charges ($/h)

- Air Traffic Service charges ($/h)

- Variable flight crew ($/h)

- Variable cabin crew ($/h)

T: Number of flight hours (h)



2. Cost Index


Fuel consumption related costs: CF . F

CF : Cost of fuel unit ($/ton)

F : Fuel consumed (tons)

Do not take as a reference

CyclicMaintenance

7%

Cockpit crew13%

HourlyMaintenance

6%

Insurance2%

Cabin crew13%

Fuel15%

Depreciation27%

Financialcharges

17%

Example of Direct Operating Costs



ECON Mach

2. Cost Index

Costs

Mach

Fixed costs

Cost of Time

Cost of Fuel

MMO

MMR

LRC

D.O.C.

ECON

Economic Cruise Mach Number(ECON Mach):the Mach number which minimizes the D.O.C.

Given:- Altitude- Weight

- Wind



2. Cost Index

ECON Mach

The ECON Mach is a function of the A/C weight,A/C Altitude and wind conditions.

Costs

Mach

Fixed costs

Cost of Time

Cost of Fuel

MMO

MMR

LRC

D.O.C.

ECON

Given:- Altitude- Weight

- Wind



2. Cost Index

Definition: Cost Index

Ratio

Possible Range:

From 0 to 999

In operations: from 0 to 300

The ECON Mach depends on Cost Index

C.I. =Cost of Time

Cost of Fuel


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2. Cost Index

Speed control and Cost Index

Increasein Mach

Increasein C.I.

C. I. = 0

C. I. = 999

ECON Mach =MMR

ECON Mach =MMO - 0.02

Fuel strategy

Time strategy

C.I. =Cost of Time

Cost of Fuel


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2. Cost Index

Costs

MachECON

LRCFixed costs

Given:- altitude- weight- wind

LRC

D.O.C.Cost of Fuel

Cost of Time

MMRMMO-0.02 MMO

Whatever the Cost Index, ECON is always includedbetween MMR (variable) and MMO - 0.02 (fixed).


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2. Cost Index


CI depends on each airline, and enables the speed oneach route to be optimized to minimize the DirectOperating Costs.

It is inserted in the MFD (Multi Function Display) beforedeparture, to enable AFS (Auto Flight System)calculation of ECON Mach according to externalparameters.

C.I. =Cost of Time

Cost of Fuel


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2. Cost Index


Some flight planning systems allow to calculate the fuelat a fixed cost index, so that the speed is optimized allalong the route as a function of the weight, altitude and

wind conditions.

C.I. =Cost of Time

Cost of Fuel


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2. Cost Index


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2. Cost Index

This table enables

you to find themost cost effectiveMach number vs.cost index, altitudeand wind as

calculated by theFMGC.

CI = 100 kg / min

FL 350Weight = 200 tWind = 50 kt

M 0.822


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