my understanding is that the CI should be able to adjust parameters in climb, cruise and descent modes (N1?) as applicable. In the PMDG product I seem to be unable to see changes in any of those modes.I have adjusted the setting from 250 to 450 during cruise and did not see a revised (mod) cruise speed.Is this correct? If so, what parameters does the CI in this product adjust?

No men!!!! Your wrong who tould you that.....CI calculates the CLB, CRZ and DES speeds.Thats one of the basics you have to have as a pilot.

Mike,I'm not sure if you can change the CI in flight. I certainly have seen changes to CRZ speed when changing the CI on the ground in the '800.Best,Martijn

Also been thinking about this CI and maybe it's in the documentation somewhere, but how do you calculate what CI you should use for your different flights?Have been using 150 as CI since going through Timothy's tutorial when the CI yet wasn't modelled but that value always gives me a FL that is far above the FL:s I normally use.Thanks in advance for any info on the subject,

Cost index is normally assigned by policy from whatever airline you happen to be flying with. What it does is calculates a climb, cruise and descent profile (if you will) that takes into account speed and cost, ie cost of fuel to go that speed. Kind of an overly simplified explanation, I'd like to see someone explain it better than I have.Our VA uses 65 as a standard cost index.

OK, thanks for the info. Anyone happen to know what SAS uses or where I could find some info about it? And also, will the CI used be different for different flights - ie how long the flight is etc?

Hi RichardSAS uses a CI of 50 for their 737s. And no it's not different for different flights.But as has been said earlier, the CI will change for each and every airline depending on their policy and the costs. It will even change between each aircraft type. The CI is basically comparing the speed dependant and the time dependant costs. High speed means high fuel cost, high maintenance costs. That has to be compared to the time costs which are the crew costs and stuff like that. Somwhere between these two equations there's an optimum. This optimum decides the CI to be used.If you have a low paid crew you can probably afford to keep them in the air for a bit longer and not spend to much on fuel and maintenance so you go for a low CI.Cheers,

unless I'm mistaken, a lower CI conservers fuel and lowers speeds, and higher makes you go faster, and burns more gas.So that would mean a cost index of 0 will get you the farthest, and the slowest speed?

Thanks alot Mats for your most informative answer, just the info I wanted!(Hm...wonder if a CI of 50 for SAS means they have low paid crew...;-) )

The easiest way to this of Cost Index is as a measure of the effect of time on operating costs. The formula of Cost Index is as follows:Cost Index = Time-related Cost / Fuel CostTime-Related Costs ---------------------------------It has long been recognised that airplane operating costs are affected not only by fuel burn, but by speed or flight time. Certain types of costs are directly related to flight time, eg: leasing costs, power-by-the-hour, crew etc. So a reduction in flight time of say, 5% will result in a 5% savings for that cost type. These costs are called

I said it before and I say it again - it's amazing how much you learn by just spending some time in this forum!!Thanks alot Skip!

Skip Fulton... would I be correct in saying ur in a Virgin Blue Virtual Airline? If so... have u got a link and would I be able to join?Cheers,Ryan

Ryan,its http://www.vozvirtual.org

Isn't it possible to have a list on wich cost index is normally used by wich airline? Where could i find that information?Cheers,Ian Udinga

>Isn't it possible to have a list on wich cost index is>normally used by wich airline? Where could i find that>information?>>Cheers,>>Ian UdingaSome airlines would probably consider that proprietary information, as it either gives away "a secret" to the competition, or reveals something about their operating costs.IE, I'd expect discount carriers to have lower cost indexes because they have relatively lower labor costs. Someone like United with it's high labor costs (and those costs include maintenance) might have a higher CI, because crew pay and a lot of maintenance work is determined by the time in the air