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ErnieAlston

Cost index

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There was a reference to this in another thread, and since this has always bugged me, I figured it was time to get the real info, so I called my pal at US Air.I know how it affected the speed, but didn't know how it is computed, so for anyone interested, heres the Readers Digest version....The number is assigned by dispatch, and is computed using multiple factors. Its based on a new plane, factory fresh, load, atmospheric conditions, altitude, winds, leg length. The number theoretically gives the most fuel effeciency but does not figure in holds, diversions, in trail spacing etc.The way its used, at least in his cockpit, it to plug in whatever dispatch assigns as a number into the FMC, then over-ride it with the MCP, so dispatch is happy, and so are the pilots. Sounds like just the way Ive been using it in FS :-)XP Pro SP2-FSX SP2AMD FX60-8800GTS-2 Gigs RAMFEX-GEX-UTUSA-FSGenesis-and a bunch of other stuffComputer optimized by www.fs-gs.com

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I've pretty much always stuck with 63. But now, what you're telling me makes me think I can make the big move to 64. It's something I've thought about for a long time, but, well, you know. 63 has been good to me for so long already. It just seems, well, so...No, I'm going to do it. I am going to switch to 64. Tomorrow.Yes, tomorrow, I am definitely going to think about switching to 64, or else keeping 63. Seriously, though, thanks for calling your airline pilot friend and passing on that info, that was nice on both your parts. I bet even the video gamer guy in "Snakes On A Plane" would have missed the cost index. Sure, he landed the plane, but he cost the airline a lot of fuel. Jeff ShylukAssistant Managing EditorSenior Staff ReviewerAVSIM

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>I know how it affected the speed, but didn't know how it is>computed, so for anyone interested, heres the Readers Digest>version....Frankly you have not learned that much, if you had searched PMDG forum the subject of Cost Index has been discussed there extensively in considerable detail over last years. This is for example a highly succinct entry from 2005: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.Michael J.http://img142.imageshack.us/img142/9320/apollo17vf7.jpg

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>>I know how it affected the speed, but didn't know how it is>>computed, so for anyone interested, heres the Readers Digest>>version....>>Frankly you have not learned that much, if you had searched>PMDG forum the subject of Cost Index has been discussed there>extensively in considerable detail over last years. This is>for example a highly succinct entry from 2005:>>>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.>>>Michael J.>http://img142.imageshack.us/img142/9320/apollo17vf7.jpgThanks for the tip Michael, but when I want real information, I prefer to go to those who know, not some 'wannabe' in a forum, and since I don't use PMDG, why would I go there?Not to mention its much easier to get understandable information from a person who flys the heavys everyday as opposed to those who wish they did. :-)I'm not saying that describes you, just my observations over the years in FS.XP Pro SP2-FSX SP2AMD FX60-8800GTS-2 Gigs RAMFEX-GEX-UTUSA-FSGenesis-and a bunch of other stuffComputer optimized by www.fs-gs.com

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>Thanks for the tip Michael, but when I want real information,>I prefer to go to those who know, not some 'wannabe' in a>forum, and since I don't use PMDG, why would I go there?PMDG forum is frequented by many real world 747 drivers, also real pilots who don't fly 747 and yes a great deal of "wannabes" too. Frankly there is a tremendous amount of solid information available there and dismissing it as information from "wannabes" is a rather crude and uninformed statement. As a good example as of this moment the most comprehensive information available anywhere on this forum about the cost index is still to be found only on the PMDG forum.Michael J.http://img142.imageshack.us/img142/9320/apollo17vf7.jpg

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I'm sure there are plenty of real pilots there, as well as lots of information, however it's much easier for me, since I have the contact, to simply call a pilot who flys these daily, and get 'real world' info on how it works. As most pilots know, in many instances there is a signifigent difference between manuals and real world procedures.I wasn't dismissing anything, there are lots of real world pilots in all forums, in fact I happen to be one. I posted the info here for those who might want to know what its for and how its used, instead of wading through endless posts trying to find accurate information. If it doesnt suit you, sorry.XP Pro SP2-FSX SP2AMD FX60-8800GTS-2 Gigs RAMFEX-GEX-UTUSA-FSGenesis-and a bunch of other stuffComputer optimized by www.fs-gs.com

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I thought Michael's simple description of how the higher cost index values put the greater importance on time, while the lower cost index values put greater importance on fuel comsumption is directly usable for flight simmers.On my sim fuel is real cheap, so I tend to use the higher values.But for the real Airlines , I suspect that CI value has crept downward in recent months.Regards.Ernie.

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Well, either your pilot friend doesn't understand cost index (which wouldn't surprise me) or you did not accurately capture what he said. Cost index, as Michael indicated, provides a way for operators to balance fuel burn-related costs versus time-related costs. The lower the cost index, the more emphasis you are putting on lowering fuel burn-related costs (which will give you lower speeds). Only a zero cost index "gives the most fuel efficiency."'Don S.

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ON the B73XNG series the typical Cost index is in the teens (13-14 is very typical)Just found it:http://www.boeing.com/commercial/aeromagaz...07_article5.pdfThis comes from a Boeing magazine. the difference in time is a minute or two over 'typical' what ever that means legs.I had heard previously that Delta was Using 80 on their 763's, but that is old info.I'd love to see what is in use today

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>The most through explanation of CI and how it's calculated>I've found anywhere is in this thread, particularly the last>post:>>http://www.pprune.org/forums/showthread.ph...ight=Cost+Index>>Here's a link to the actual document the last post refers to.https://www.iata.org/NR/ContentConnector/CS...ex_Material.pdfHeavy stuff, but if someone really really wants to know, there it is.Regards.Ernie.

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