Archive > Technical discussions
PMDG Fuel cost Index
EHM-1343 Jonathan:
ok....thanks. When i got this, i din't realise how accurate things were, everything down to fuel comsumption, its amazing:o
EHM-0654 Murray:
--- Quote ---Originally posted by Razza
ok....thanks. When i got this, i din't realise how accurate things were, everything down to fuel comsumption, its amazing:o
--- End quote ---
In that case... ;D
Hey kids! Don't forget to enter the cruise temp and wind forecasts (temp on PERF INIT, winds on LEGS), as they have a *huge* bearing on the fuel usage calculations... The PMDG FMC doesn't model either of these as well as the PM FMC, but does take them into account when doing it's fuel usage calcs.
EHM-1539 Pierre:
99 or 999 ? Both.
Depending on the FMC version and manufacturer the cost index is usually 0-99 OR 0-999.
EHM-0654 Murray:
Well, to quote from my 737NG FMC User's Guide, COST INDEX is the:
--- Quote ---[*]Ratio of other crew and maintenance costs compared to the cost of fuel. The lower the index, the more influence fuel price has on the speed schedule. The higher the index, the greater influence time related costs (i.e. maintenance and crew) have on the equation.
[*]0 causes ECON speed to be approximately Max Range Cruise in zero winds. 500 results in minimum flight time.
[*]Adjusting CI to meet operational schedule or ATC requirement defeats cost studies if computed by your engineering department.
[*]RTA function adjusts Cost Index to meet arrival times. Ed: PMDG FMC doesn't do RTA. Don't know about PM FMC.
[*]Ref: Cost Index, CRZ section.[/list]
--- End quote ---
Hence my assertion that for the 737NG CI can be 0-500. :) And as far as usage goes, on the same page, a little further down, it gives this nugget of wisdom:
--- Quote ---Technique For a quick set-up to prioritize fuel conservation, enter a CI of 36 to shorten climb phase and for a 280kt descent. Then select LRC on CRZ page.
--- End quote ---
EHM-1343 Jonathan:
This will come in very handy...when you say PM FMC, what do you mean...which manufacturer
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