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Guest teeloo

Cost Index.... how does it work?

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Guest teeloo

Hello,Two questions:1) What numbers should I use for Cost Index.2) Where does this number come from?I know minimum is 0 and max is 500.500 = lots of fuel use (safe time)?0 = very economical (time no issue)?What is the 0-500 scale coming from?regardsTeeloo

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hii cant be to much help but, i dispatched a air malta 737-300 this summer and in the cockpit was a sticker saying cost index 34since then i have always used this figure...hope this is of some help to youif any one can elaborate further pls do."Lairy"Liam Reynolds

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I think the scale runs from 0-1000 but I may be wrong (it may differ between various airplane models).Cost Index is defined to be that speed which minimizes total cost (time+fuel). It

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A captain on our team said that a CI over 100 does not make really any big differnce in savings on the NG. CI is different for each airline because it's directly related to their costs. It is exactly time VS fuel and operation costs. I see from 20s to 60s most commonly around upper 20s though..[h4]Randy J. Smith[/h4]

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Guest nattydread

i thought I remember it being siad that 80 was normal. this was with the old Fly!II PMDG 777 FMC manual though. Thats the setting I always use.

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Guest teeloo

Anybody knowing the formula?I know it is directly about fuel vs time etc.But anybody knowing what Boeing implemented as a formula?After all, it's their FMC telling what the engines should burn.I am interested in anybody knowing the calculations. It seems like it is rather complicated (dollars vs fuel cost vs engine perf.)Teeloo

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Cost Index = Time-Related Cost ($/flt.hr) / Fuel Cost (cents/pound)CI of 999(9): Premium exists on time. Corresponding speeds are maximal in all flight phases. The FMC will build a small buffer from the barber pole (VMO/MMO).CI of 0: This is the case of highest influence of fuel cost ni the oerating bill, or a requirement for max range. ECON minimizes consumption in all phases. Climbs at max rate, cruises at little less than LRC (Long Range Cruise), and descends at close to moin drag.

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Guest Crazed One

I found this in an earlier search, an Airbus Cost Index guide.http://www.iata.org/NR/ContentConnector/CS...ex_Material.pdfI also found that Southwest Airlines seems to use 36 for CIAnd for some reason I had a 19 CI for Fed Ex cargo flights, I cant remember where I came up with that number though.And I had read that during flight, if behind schedule bump your CI up to 100-110, I am sure its pilot/airline dependent though.Would be neat if someone kept an updated Cost Index by airline/flight page :)

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Guest teeloo

Thanks all of you!Great!The Airbus one is really coolTeeloo

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I am sure its pilot/airline dependent though. Pilots have nothing to do with CI other than crunching them into the FMC. Flight dispatch are the guys who provide this information along with your route and fuel. There is NO correct CI because each airline has different COSTS. [h4]Randy J. Smith[/h4]

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Guest Crazed One

What I meant about pilot dependent, was bumping the CI up on the FMC if behind schedule for arrival, from whatever the original airline CI was, while in flight.

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Yep, that is correct although from a what I understand the purpose of CI is pretty much thrown out the window when one need to manipulate it to achieve some tactical goal such as make up for lost time. Since the purpose of CI is to fly as economically as possible any changes to it screws up the calculations done by the management. Reduce it and the cost/flight hour increases, increase CI and the fuel cost increases. Arriving on time is not a factor for the CI calculation, but just as yousay the CI can be used to increase/decrease the ETA.Since I

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Guest Hawkeyeted

I think the CI is calculated based on a baseline fuel cost for a given company.United Airlines; the cost for a gallon of Jet-A in Chicago (hypothetically) is $1.00. That is the baseline (CI 100). If you are going to fly from KORD to KJFK, and fuel in KJFK is $1.25 a gallon, the CI for the KORD to KJFK route is 75 (since fuel is 25% more expensive at KJFK). Conversely, if you fly from KORD to KLAX and Jet-A is $.75 a gallon in Los Angeles, the CI for that route is 125.I figure that if you're using a CI of 500, you're getting the fuel for free.....If I'm wrong here, please educate me....

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Guest Soulman

CI differs for each segment and also each aircraft depending on the leasing terms. A high CI gives best time while low gives best cost. Ours are normally on the low end at around 16 or so.

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I recently tried different CI values to see if they had any effect on the suggested FL in the FMC (thought they would have) but didn't notice any difference no matter what CI value I entered. So maybe that's correct that the CI isn't modelled...?

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Guest Hawkeyeted

I thought I saw the CI work in the FMC. Not in cruise FL's, but in flight speed. Enter a CI of 50 and note the cruise speed (around .77-.78?) and then enter a CI of 500 and see if cruise speed jumps to .8 or so.

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OK, I will have a look on next flight but shouldn't the CI value also affect your FL if the calculations are as their real counterparts?

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Guest Hawkeyeted

I would believe that in reall life, the CI DOES effect the FL's AND cruise speed. I just don't think it is in PMDG. Maybe I'm all wrong and it isn't modeled at all. I just thought I remember seeing CI effecting the in flight cruise speed.

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Guest gustav.m

Hi Teeloo,Timothy Metzinger in his excellent advanced manual advises:- "The COST INDEX is not modeled in the sim yet so any number will give the same result." I believe his ball park figure is actually 150Hope this helps.Regards,Gustav.

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