View Full Version : FMC Cost Index
Red Comet
11th Dec 2004, 09:24
Can anyone tell me how the optimum fmc cost index is calculated for the 737 ?
Alaskan Timber
11th Dec 2004, 13:36
Interesting question, at my company they didn't find it out themselves. So we always fly with a fixed CI.
Wizofoz
11th Dec 2004, 14:08
It is established by dividing aircraft hourly cost (Crew, maintenance costs etc.) by the cost of fuel. The higher the fuel cost, the lower the cost index, and the closed Econ speed will be to maximum range.
Alaskan Timber
11th Dec 2004, 14:48
Theoratically this would mean that for several destinations you would need a different CI, because of fuel price differences etc.
Is your company also using a fixed CI or do they have different ones for each destination ?
Alaskan Timber, cost index will be different for every route due to the various fuel prices. We cheated in that we just settled on an average value based on all foreign destinations.
Red Comet, suggest you avoid cost index unless your airline has the manpower to maintain its accuracy, garbage in, garbage out, if wrong it will end up costing you money!
Mutt
RC - my current operator has a pilot-accessible programme based on current fuel costs which does calculate CI, but, as Mutt says, it needs to be kept up-to-date or it is less reliable. I would not go so far as to castigate it as 'garbage' (:D ) should it be a tiny bit OOD, as it will still be broadly ok.
ATB
catchup
11th Dec 2004, 18:13
Is it a bug?
No, it's a feature.
:)
Shore Guy
11th Dec 2004, 18:36
The Bible....
http://www.fmcguide.com/
:O :O :O
There are other big picture costs to consider too.
RPT operations need to be able to publish a schedule and keep to it. If you then want to vary cost index on each flight depending on the vagaries of fuel prices you will surely incur other costs not considered by the CI concept.
Say the cost of fuel rises significantly over a short period of time and you therefore decide to use a lower cost index. You would have to ask some questions first...
How much does it cost to arrive later than the published schedule?
Would this not put pressure on passenger connections, aerobridge utilisation, ground staff resoucses, as well as on-time departure for the next service?
How much is THAT going to cost?
It's a can of worms!
Sorry BOAC but i stand by the "garbage in, garbage out" statement! :) Using operations/mx costs associated with a state run and totally overmanned airline combined with cheap fuel provides some extremely interesting cruise speeds!
The cost index formula is only as good as the information used for the calculation :)
Mutt.
Another helpful thread:
Variable Cost Index (http://www.pprune.org/forums/showthread.php?threadid=139504&highlight=Cost+Index)
:ok:
Chimbu chuckles
16th Dec 2004, 07:23
Simple really....running late and going a long way upwind...cost index 100...not running late or downwind...cost index 60.:E
Mutt - there was a :D there. Know what you mean though, from personal experience.....;)