Your Cost Index and Mach SPD over the Atlantic
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Your Cost Index and Mach SPD over the Atlantic
Good Day,
I am planning on writing a paper for college on the affect rising fuel costs have had on cruise speeds and cost indeces over the past decade for commercial aircraft.
So for those of you that don't mind giving me some info. i would appreciate:
Aircraft type:
Cost Index: (if not applicable then state you CRZ mach used)
CRZ Mach used over the Atlantic or when on a NAT: (if applicable)
Airline: (at your discression)
Feel free to add any extra info.
thanks in advance!
I am planning on writing a paper for college on the affect rising fuel costs have had on cruise speeds and cost indeces over the past decade for commercial aircraft.
So for those of you that don't mind giving me some info. i would appreciate:
Aircraft type:
Cost Index: (if not applicable then state you CRZ mach used)
CRZ Mach used over the Atlantic or when on a NAT: (if applicable)
Airline: (at your discression)
Feel free to add any extra info.
thanks in advance!
Last edited by B-HKD; 14th Apr 2010 at 21:49.
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Mach speed over the atlantic in the NAT track system must be a constant mach! Cost index doesn't realy apply over the atlantic. When you get your NAT track clearance, you are given a specific mach speed to maintain. You can fly a cost index before and after the NAT track system, but over the atlantic, you must maintain a constant mach speed.
On the 744, we usually fly .85 +- .01
On the 744, we usually fly .85 +- .01
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Years ago it was .85 for B-747-400 and Cost Index 250.
Now reduced back to Cost Indexes around 40, so Mach .82-83. Fly at constant Mach on the Tracks as previously mentioned, but we are supposed to ask for a Mach re-clearance at various times, as fuel burns down or winds change.........but most are too lazy to do it.
Flying so close to Max Range is getting silly.
Now reduced back to Cost Indexes around 40, so Mach .82-83. Fly at constant Mach on the Tracks as previously mentioned, but we are supposed to ask for a Mach re-clearance at various times, as fuel burns down or winds change.........but most are too lazy to do it.
Flying so close to Max Range is getting silly.
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Few years ago we were flying 75s round at CI 55-65 generally. Flying round now at 21-23 usually, and Mach numbers .78-.79.
Flying the 76s round at the moment (recently fitted with winglets) at CI 6-10 and depressingly slow .76 - .77ish!!
Flying the 76s round at the moment (recently fitted with winglets) at CI 6-10 and depressingly slow .76 - .77ish!!
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Default for BA747 (as if 6 months ago when I took VR) was:
CI=0 for climb than CI=90 until NAT then typically fixed M0.85, then CI=90 to 10,000ft etc.
Variation from above if quick flight time, in which case CI for cruise and mach for fixed speed portions could be varied downwards to achieve schedule, eg CI=0 and Mach 0.82.
CI=0 for climb than CI=90 until NAT then typically fixed M0.85, then CI=90 to 10,000ft etc.
Variation from above if quick flight time, in which case CI for cruise and mach for fixed speed portions could be varied downwards to achieve schedule, eg CI=0 and Mach 0.82.
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Low Cost Index etc
B-HKD, concur with most of above posts. We fly A330's on CI's of 14-16 now, gives M.81 in cruise but in MNPS this must be pegged at your OCA CLX speed.
An interesting development of low Cost Indices is that the descent speed becomes very slow (A320/1=250kt, A330=260kt) and one just holds other traffic up, so ATC usually ask you to speed up anyway! Oh well, we did try...
An interesting development of low Cost Indices is that the descent speed becomes very slow (A320/1=250kt, A330=260kt) and one just holds other traffic up, so ATC usually ask you to speed up anyway! Oh well, we did try...
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CI again
Good to see that you all have slowed down
CI is of course (variable) Cost of Time divided by the Cost of Fuel (using different parameters depending on metric or non-metric numbers).
Now, Cost of Time doesn't change often (contract negotiations, change of MRO), however, the Cost of Fuel does.. compared to 12 months ago the average fuel price is 30% higher and so, consequently, your CI values should be about 30% lower than last year when you all posted to this thread.
In theory.
Once CI values approach the lowest 10s other factors start playing a role as well.. by now schedules are stretched upwards and additional crews are required to fill those higher block times, etc., creating additional cost; not to mention of course that aircraft are ECONning at very low speeds and high alphas, even close to stall. Not good.
And yes- ATC still doesn't get it after all these years, even though most everybody is cruising in sloooowly nowadays.
So what is wise here?
Cruising at fixed Mach speeds will always cost more in relation to CI-managed cruise, as ECON cruise takes into consideration the impact of winds and temperatures on specific range, resulting in optimized speeds for the given circumstances compared to the more coarse corrections used in fM flying.
Fuel efficiency-wise MRC (or 1% less, LRC) just won't do compared to CI=0
Maybe it's time for a CORRECTED Cost Index, a CI value which is looped back to scheduling and takes into consideration the overall network effect of slowing down or speeding up the fleet; city-pair specific fuel price deltas of course (sector-specific CI values) and additionally, specific aircraft operating limitations by only allowing a certain band of ECON speeds, a minimum and a maximum for example.
The one who has the correct answer can sell a very nice tool
Max
CI is of course (variable) Cost of Time divided by the Cost of Fuel (using different parameters depending on metric or non-metric numbers).
Now, Cost of Time doesn't change often (contract negotiations, change of MRO), however, the Cost of Fuel does.. compared to 12 months ago the average fuel price is 30% higher and so, consequently, your CI values should be about 30% lower than last year when you all posted to this thread.
In theory.
Once CI values approach the lowest 10s other factors start playing a role as well.. by now schedules are stretched upwards and additional crews are required to fill those higher block times, etc., creating additional cost; not to mention of course that aircraft are ECONning at very low speeds and high alphas, even close to stall. Not good.
And yes- ATC still doesn't get it after all these years, even though most everybody is cruising in sloooowly nowadays.
So what is wise here?
Cruising at fixed Mach speeds will always cost more in relation to CI-managed cruise, as ECON cruise takes into consideration the impact of winds and temperatures on specific range, resulting in optimized speeds for the given circumstances compared to the more coarse corrections used in fM flying.
Fuel efficiency-wise MRC (or 1% less, LRC) just won't do compared to CI=0
Maybe it's time for a CORRECTED Cost Index, a CI value which is looped back to scheduling and takes into consideration the overall network effect of slowing down or speeding up the fleet; city-pair specific fuel price deltas of course (sector-specific CI values) and additionally, specific aircraft operating limitations by only allowing a certain band of ECON speeds, a minimum and a maximum for example.
The one who has the correct answer can sell a very nice tool
Max
Last edited by max payload; 21st Oct 2011 at 12:33.
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B777-300ER, CI 26 to 29, too slow. In the CFP the constant M is filed with around .84 to .85 it depends on the day and time.
Before reaching the NATS entry point the speed is re-checked at the FMC Legs Page and E/ is entered at the Exit point. The speed increases at the entry from ECON to the cleared track speed and at the Exit point it decreases again to ECON.
On the NOPAC it is not that busy as the NATS, you do not need a extra clearance to enter the tracks. That is automatically done with your ATC clearance on the Ground.
Another colour another name, the rest is the same, no big diffrences.
Fly safe and land happy
NG
Before reaching the NATS entry point the speed is re-checked at the FMC Legs Page and E/ is entered at the Exit point. The speed increases at the entry from ECON to the cleared track speed and at the Exit point it decreases again to ECON.
On the NOPAC it is not that busy as the NATS, you do not need a extra clearance to enter the tracks. That is automatically done with your ATC clearance on the Ground.
Another colour another name, the rest is the same, no big diffrences.
Fly safe and land happy
NG
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B777 - 200ER and B777 - 300 ER
Normal CI used is CI 50 for both types.
This gives M.82 - M.83 for the 200ER and M.83 - M.84 for the 300 ER.
On the North Atlantic use M .83 ( NO CI used after the crossing the OEP until leaving Oceanic airspace, although westbound some of the Canadian airspace has separate rules) for both types.
Normal CI used is CI 50 for both types.
This gives M.82 - M.83 for the 200ER and M.83 - M.84 for the 300 ER.
On the North Atlantic use M .83 ( NO CI used after the crossing the OEP until leaving Oceanic airspace, although westbound some of the Canadian airspace has separate rules) for both types.
