What cost index does your airline use and why

[accinelli]

Flew on UAL the other day and was surprised to see a Cost Index of 27 being used.
What cost index does your carrier use. Anyone using a variable cost index out there?

 

[GuppyWN]

28 on the -300 and 36 on the -700. Why? Don't know. Laziness I presume. It would be easy to compute it each leg depending on winds and weight.

Gup

 

[bearcat]

CAL - we are using 15. But it is very unrealistic with a .74/256 descent into newark. Actually we use the fligh plan to determine our cost index. Apparently using cost index to adjust your FP speed is much more fuel efficient than using the CRZ/DES pages. It is an auo throttle thing. Less throttle jockey-ing.

 

[TWA Dude]

Dispatch assigns it based on our planned flight time vs scheduled block time. It's either 30, 50, or 70.

 

[waterski]

35....

 

[MD11Drvr]

200 most of the time and 100 on a reclear flight plan.

 

[FlyingSig]

DAL -Different on every leg and on portions of legs (flight plan software optimizes it).... a flight may start out with 23 and end up with 70 by the top of descent point...

For some reason though the flight planning software doesn't seem to recognize the need to put it at 300 on the last leg of a trip before the commute home

 

[Marko Ramius]

It is an auo throttle thing. Less throttle jockey-ing.

It's also the reason that LRC tends to be slower than cost index 0 vs. them being equal.

 

[SuperFLUF]

At CAL the cost index uplinked by dispatch varies (daily or weekly?) based on fuel cost, mx costs, crew costs...etc. Lately on the 757 it has been between 8 & 11.

This is our minimum cost index to be used if we are on time or early. If we are running late we bump up the cost index (using econ climb, crz, desct speeds) until it gives us an on time arrival. Of course we have to adjust the descent speed to fit the needs of the arrival airport but other than that it works real good and lasts long time.

 

[StaySeated]

At F9 we use 10 or 11. Crazy low if you ask me but supposedly we are getting new software that will optimize the CI on every leg. I can't figure out how a long slow descent with power saves fuel, but they say it does.

 

[Freight Dog]

20 on our ETOPS legs unless we're running late - then it's a fair game to stay on time.

30-45 on domestic legs.

 

[starchkr]

10 is pretty crazy stayseated...it drives me nuts...I always want to fly at redline, but that is just the old freight dog in me coming out. We are told that we do fly the most economical fleet in the nation right now because of our cost idex use...but i too wonder about the long slow descents with power. Completely goes against everything taught while flying a turbine aircraft, but oh well.

 

[radarlove]

28 on the -300 and 36 on the -700. Why? Don't know. Laziness I presume. It would be easy to compute it each leg depending on winds and weight.

Gup

Actually, I had a SWA friend talk about this exact thing, since I wanted to know what the low cost beast used to save gas. I was totally surprised.

It appears that SWA uses a cost index that forces the 737-700s and 737-300s into the 737-200 descent profile, a leftover from trying to pretend the 737-200 and the 737-700 are the same airplane.

He claims that those two CIs force a 280 knot descent and that the guys in charge have forgotten that SWA doesn't fly 737-200s any more.

For what it's worth, maybe he's nuts.

 

[McNugget]

757 = CI 60, gives about .80 cruise.

 

[Propblast]

B6=35 usually (although I saw 80 last week).

-PB

 

[venr122]

Heres a follow up question....

The highest altitudes available in the box are in ECON, vs. a hard coded speed....so why, when ECON is showing .80 at say 35,000, why then when .80 is hard coded the altitude drops, just a couple hundred feet usually but does this every time.

 

[SuperFLUF]

Heres a follow up question....

The highest altitudes available in the box are in ECON, vs. a hard coded speed....so why, when ECON is showing .80 at say 35,000, why then when .80 is hard coded the altitude drops, just a couple hundred feet usually but does this every time.

Probably because ECON does not maintain that .80 number the whole way. It varies based on gross weight, OAT, winds....etc.

 

[SuperFLUF]

........ I can't figure out how a long slow descent with power saves fuel, but they say it does.

That must be an Airbus thing. The econ descent profile in all the Boeings I've flown is an idle descent no matter what the speed. So the lower descent speed translates to a longer time period at flight idle and thus saves fuel.

 

[geshields]

Does anyone use the RTA function to get the CI when you are runing late?

 

[FlyWolf]

18 at Midex, why? because thats what the numbers guru guy say we should use

 

[IAHERJ]

Anything that gives you the cruise speed that is required either for the north Atlantic crossing speed as filed by your dispatcher or whatever gets you on the ground at the time the flight plan wants you to touch down (given the variable taxi times). I've used everything from 1-250 on the 757/767. CAL doesn't really care what you use as long as you get the plane from point A- to point B on time using the least amount of fuel possible.

IAHERJ

 

[Beetle007]

An honest manager will admit they pulled the number out of their A##.

Do America West and U.S. Airways have a different cost for the Airbus? I would be curious to see how they come to the conclusion of which cost index is best.

 

[F/O]

999....have to catch my commuter flight...

 

[starchkr]

That must be an Airbus thing. The econ descent profile in all the Boeings I've flown is an idle descent no matter what the speed. So the lower descent speed translates to a longer time period at flight idle and thus saves fuel.

The Airbus descent profile uses what Airbus calls a zero drag idle, this is far from true idle which is used everywhere else (or so i have heard). Airbus holds power in the engine usually about 10-15 percent N1 above a true idle when on a managed descent. This, they say, creates zero drag from the engine fans spinning faster(and using more gas) which in turn gives a better fuel economy...again, so they say.

You know higher speed flight profiles have been used on the Airbuscool: ), and they actually saved more gas than the company had said we were to burn doing a strict CI 10. High speed climb, higher speed cruise with a 2-1 descent (more like a 2.5 - 1) at true idle and little to no power added until the requirement for stabilized flight again during the approach.

 

[Doug Parker]

.

999....have to catch my commuter flight...

Amen, brotha !!!



.

 

[minrest]

On CAL's 737 we use CI 15 but adjust accordingly to arrive on time. We have been instructed not to descend in CI15, rather hard-code your cruise mach and 280 kts. Apparently the slow descent was not making friends with ATC.

We regard to idle descents, we currently have two FMS software versions. Version 10.6 provide an idle descent between the first two hard descent points and then creates a descent profile that allows the aircraft to slow down during the descent (rather than descend at say 300 knots at idle and then shallow out the descent in the last 2,000 feet to slow. They say that this is a much more economic profile and it also allows for better speed changes during the descent as the engines are spooled up and the power can be reduced if necessary.

We should upgrade to 10.7 in the summer and will no longer have to deal with 10.6. BTW, there is a very complicated, pain in the ass procedure that we use to trick the FMS into providing a normal flight idle descent.

-minrest

 

[atldc9]

We use CI 25. The powers that be say it is as close to LRC as we can get. It typically has you climb between 290 - 311, transitioning to .75 - .775. Cruise is .75 - .775 depending on headwind or tailwind, and descent ends up transitioning to 287. Too slow for me.

The barber pole is a goal, not a limitation, and Boxes don't bitch. I miss freight.

 

[Bjammin]

80 usually.

0 if way early.

250 if late.

Higher if need to meet curfew.

 

[Phaedrus]

200 or so.

 

[Occam's Razor]

NWA Airbii use 60. There were some initial issues with using opt altitudes and the original CI of 30 when NWA launched the Airbus in '90. The stupid thing slowed down into a headwind, and went faster with a tailwind!

Airbus blamed Honeywell. Honeywell blamed Airbus. NWA mediated the Family Feud and now 60 is the law of the land for us.

Seems to work fine. .80m into the wind and a variable .78-79m with it.