easyJet Cost Index & Econ Descent
Ut Sementem Feeceris
Lordy, some people are certainly getting a bit hot under the collar with this one.
Fact: A slower descent uses less fuel due to not being at cruise thrust for so long. Think about it. An extra 3 mins at 40kgs/min and descent at 320 knots = 120 kgs extra burn.
Fact: If you are going to get in peoples way, then at ATC request you may speed up.
COMMON SENSE: ASK ATC WHAT SPEED THEY WOULD LIKE IN THE DESCENT BEFORE YOU START IT. IF THEY SAY FREE SPEED, GREAT YOU CAN APPLY THE SOP AND FEEL ALL WARM AND FUZZY. IF THEY SAY 290 KNOTS FINE, DO IT.
Some posters on here dismiss a saving of 50kgs per flight - well eJ operate close to 1000 sectors per day so it does have a significant effect on their operation. We also use single engine taxi in, have been trialling single engine taxi out and minimum use of APU on turn around. But all of these can be over-ridden by the Commander if deemed inappropriate for any reason. Any management that does not actively pursue sensible fuel saving practices is not doing its job.
I expect to see CI determined descent becoming more widespread as the price of fuel continues to rise. So as one other contributor said, perhaps those roaring round with their hair on fire will be the ones being vectored. PRNAV is also going to become more influential over the next few years - and we really will be "pilots monitoring".
There also seem to be some very bitter and twisted individuals on here.
Fly safe everyone.
A4
Fact: A slower descent uses less fuel due to not being at cruise thrust for so long. Think about it. An extra 3 mins at 40kgs/min and descent at 320 knots = 120 kgs extra burn.
Fact: If you are going to get in peoples way, then at ATC request you may speed up.
COMMON SENSE: ASK ATC WHAT SPEED THEY WOULD LIKE IN THE DESCENT BEFORE YOU START IT. IF THEY SAY FREE SPEED, GREAT YOU CAN APPLY THE SOP AND FEEL ALL WARM AND FUZZY. IF THEY SAY 290 KNOTS FINE, DO IT.
Some posters on here dismiss a saving of 50kgs per flight - well eJ operate close to 1000 sectors per day so it does have a significant effect on their operation. We also use single engine taxi in, have been trialling single engine taxi out and minimum use of APU on turn around. But all of these can be over-ridden by the Commander if deemed inappropriate for any reason. Any management that does not actively pursue sensible fuel saving practices is not doing its job.
I expect to see CI determined descent becoming more widespread as the price of fuel continues to rise. So as one other contributor said, perhaps those roaring round with their hair on fire will be the ones being vectored. PRNAV is also going to become more influential over the next few years - and we really will be "pilots monitoring".
There also seem to be some very bitter and twisted individuals on here.
Fly safe everyone.
A4
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Taxiing on one engine?
Taxiing on one engine?
At one of our bases it is "encouraged "all the time.
The down side of this?
When on the odd occasion we do an Aircraft swap, during the walkaround I found the Engineers were changing a Brand New Tyre, which had been very badly worn on the shoulder of one side. This they attributed to the taxiing on one engine policy and were ripping there hair out over it. This tyre wear is apparently quite common with the one engine taxiing practice.
So what the company is actually saving becomes a bit of a mystery, as you now have an extra unforeseen cost involved plus the 25 min turnarounds go way out of the window. Not to mention the safety implications of worn tyres.
BR.
At one of our bases it is "encouraged "all the time.
The down side of this?
When on the odd occasion we do an Aircraft swap, during the walkaround I found the Engineers were changing a Brand New Tyre, which had been very badly worn on the shoulder of one side. This they attributed to the taxiing on one engine policy and were ripping there hair out over it. This tyre wear is apparently quite common with the one engine taxiing practice.
So what the company is actually saving becomes a bit of a mystery, as you now have an extra unforeseen cost involved plus the 25 min turnarounds go way out of the window. Not to mention the safety implications of worn tyres.
BR.
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You can't really blame the guys in the front, if the management are getting really draconian about SOPs.
However, I feel SOPs are the fundmentals on which we operate, and not always the absolute best way to operate on the day, phase of flight etc. Some things don't really need to be deviated from, while other things can only be viewed as being commercially expeditious to do so.
Fly a CI descent, unless there is a good reason to do otherwise- traffic flow, atc request.
I have noticed at FARO, that atc are not always all that good, and all the planning in the world suddenly goes out the window when instead of the expected arrival that you started on, they suddenly short cut you and cut out 15 or 20 track miles.
Good judgement will have you fly anything other than CI speed, to maintain any separation and to ensure you keep position in the flow. Unless you want to go 'unable to comply' and move from 2, or 3 in the flow, to 6 or 7 which I am sure is something ATC could also do to the slower aircraft to keep the flow going for the faster aircraft, or even send the odd one or two slow aircraft to the hold, to keep the flow going.
I would have thought the aim should be an overall fuel saving across all the scheduled flights over a period, not rigidly having EVERY single flight return a fuel saving of x-kg, irrespective of the disruption that may occur.
In london certainly, the big picture is keeping ALL the traffic moving as steadily as possible for a variety of reasons, and is done by various methods but seemingly primarily by speed control. It's a shame that their ability isn't seen in other places.
By being commercially expeditious I would consider CI, flighttime, turnaround, traffic flow, plus any number of other factors that may pop up.
One factor that I am sure will not be reviewed is the flight schedule. While everyone is slowing aircraft down, to optimise the fuel burn, the potential for delays will start to creep in with a knock on effect further on.
As for the CI itself.
B738, ci35 we fly mostly. Descend at 279kt, until the 250/fl100 restriction.
At ci25, descend at 256kts. 23kts difference, but about 8minutes more idle descent time. Or more importantly, 8 minutes less at cruise power.
I can't remember the figures exactly, because it was over a year ago that we last had the very low ci imposed. I expect it to turn up soon though.
However, I feel SOPs are the fundmentals on which we operate, and not always the absolute best way to operate on the day, phase of flight etc. Some things don't really need to be deviated from, while other things can only be viewed as being commercially expeditious to do so.
Fly a CI descent, unless there is a good reason to do otherwise- traffic flow, atc request.
I have noticed at FARO, that atc are not always all that good, and all the planning in the world suddenly goes out the window when instead of the expected arrival that you started on, they suddenly short cut you and cut out 15 or 20 track miles.
Good judgement will have you fly anything other than CI speed, to maintain any separation and to ensure you keep position in the flow. Unless you want to go 'unable to comply' and move from 2, or 3 in the flow, to 6 or 7 which I am sure is something ATC could also do to the slower aircraft to keep the flow going for the faster aircraft, or even send the odd one or two slow aircraft to the hold, to keep the flow going.
I would have thought the aim should be an overall fuel saving across all the scheduled flights over a period, not rigidly having EVERY single flight return a fuel saving of x-kg, irrespective of the disruption that may occur.
In london certainly, the big picture is keeping ALL the traffic moving as steadily as possible for a variety of reasons, and is done by various methods but seemingly primarily by speed control. It's a shame that their ability isn't seen in other places.
By being commercially expeditious I would consider CI, flighttime, turnaround, traffic flow, plus any number of other factors that may pop up.
One factor that I am sure will not be reviewed is the flight schedule. While everyone is slowing aircraft down, to optimise the fuel burn, the potential for delays will start to creep in with a knock on effect further on.
As for the CI itself.
B738, ci35 we fly mostly. Descend at 279kt, until the 250/fl100 restriction.
At ci25, descend at 256kts. 23kts difference, but about 8minutes more idle descent time. Or more importantly, 8 minutes less at cruise power.
I can't remember the figures exactly, because it was over a year ago that we last had the very low ci imposed. I expect it to turn up soon though.
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I work for said airline. I'll fly whatever speed I like cos I'm the bloody captain. If I think 300kts in the descent, or lowish level cruise, is more appropriate for ATC and everyone else around me then that's what I'll do. "Non-standard" if it's safe and appropriate to the situation is the flexibility which keeps the operation in the sky, and my brain from seizing up under the ever increasing grind of 'procedure for every eventuality' mentality of my company.
Long live the freedom of thought that we call airmanship.
JB
Long live the freedom of thought that we call airmanship.
JB
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I dont like to see this kind of mentality creep into aviation."I am doing what I was told to do".Pilots are better than that.ATC will expect and plan around a jet descending at 300,then 250 and then 210/220 in the latter stages.The point though is fly what they tell you.Thats sacrosanct.A company that has its jets descending at 250 or 260 @FL300 will upset the system for everyone else.They may think they're the only ones in the sky but they're not.Some days you'll get slowed up early,others you'll be asked to maintain high speed for as long as possible.Think flexible and always comply.Speed control is a great tool for ATC and denying them that for some pansy-ass reason like SOP's is not pukka.You're a pilot not a monkey.
If the company CI generated a descent of 265,I'd override it to 300 manually based on common-sense and professionalism.ATC compliance,providing its safe for you and your passengers,is a test of your airmanship.I cannot imagine
a pilot saying "unable to comply due SOP" to a controller in the States.He'd get taken out of sequence.They dont have time for such antics.
If the company CI generated a descent of 265,I'd override it to 300 manually based on common-sense and professionalism.ATC compliance,providing its safe for you and your passengers,is a test of your airmanship.I cannot imagine
a pilot saying "unable to comply due SOP" to a controller in the States.He'd get taken out of sequence.They dont have time for such antics.
I wish some people would read the bl00dy NTC. It says if the Captain feels he needs to fly at a higher speed to fit into the ATC situation thats fine.
Rananim - we will not refuse to fly an ATC speed due to SOP. We fly the C.I speed until ATC require a speed. Thats if we have not flown a higher speed already as we think the ATC environment dictates.
Rananim - we will not refuse to fly an ATC speed due to SOP. We fly the C.I speed until ATC require a speed. Thats if we have not flown a higher speed already as we think the ATC environment dictates.
Ut Sementem Feeceris
Some of the replies on here really do come across as very childish. The NTC clearly states that the Captain can modify the speed to fit in with ATC requirements - is that too difficult for some to understand 
Many contributors have said things like "I'm a pilot, not a monkey", "I'm the bl00dy Captain" - would it be incorrect if I suggested that perhaps said people started to behave as such. As a Captain you are a role model - what impression do you think you give to a fresh faced FO if you decide to ignore an SOP? Would you do the same for stable at 1,000'/500'? Thought not. Would you do it on a Line Check. No, thought not. Even if you don't agree with it, it's their trainset and you are paid to comply with Company procedures - and the procedure allows you to modify your speed, if necessary,so where's the problem?
Comments like "please vector us to the back of the queue to teach the Company a lesson" are pathetic. Shame on you - grow up, read the NTC and start acting like a Professional or find another career.
Yes I did get out of bed the wrong side.
A4
Many contributors have said things like "I'm a pilot, not a monkey", "I'm the bl00dy Captain" - would it be incorrect if I suggested that perhaps said people started to behave as such. As a Captain you are a role model - what impression do you think you give to a fresh faced FO if you decide to ignore an SOP? Would you do the same for stable at 1,000'/500'? Thought not. Would you do it on a Line Check. No, thought not. Even if you don't agree with it, it's their trainset and you are paid to comply with Company procedures - and the procedure allows you to modify your speed, if necessary,so where's the problem?
Comments like "please vector us to the back of the queue to teach the Company a lesson" are pathetic. Shame on you - grow up, read the NTC and start acting like a Professional or find another career.
Yes I did get out of bed the wrong side.
A4
Right Way Up, that's the plain and simple truth that I and several other posters have said two pages ago: SOP=econ till ATC instructs otherwhise.
Apparently no one cares, they just want to have a go at SOP-huggers and showcase their airmanship, whatever that is..
Apparently no one cares, they just want to have a go at SOP-huggers and showcase their airmanship, whatever that is..
Penko, agreed. The irony is that those people having a go at the SOP have not even bothered to read it properly in the first place.
A4 - also agreed. Some of the egos on this thread suggest there would be no room in the flight deck for anyone else anyway.
A4 - also agreed. Some of the egos on this thread suggest there would be no room in the flight deck for anyone else anyway.
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It has come up about four times already in the thread but it seemd to still get ignored. The SOP specificlly says that CI should be flown unless the Skipper decides otherwise based on the OVERALL ATC ENVIRONMENT. So no excuse to ignore ATC or send people behind you into the hold.
The most fuel economical descent is not 210 kts (close to minimum sink speed) as we are not trying to remain airborne the longest. The ideal fuel profile is a top of descent for a continuos descent at best glide speed (close to 250 kts) and iddle thrust. The airbus does not plan an iddle thrust continuos descent. It plans a partial thrust descent, followed by a geometrical path between constrains, followed by a level segment at the end. It does this presumably to avoid those peski pilots getting all hot and high and because all those years back it was decided that extra margin was worth the extra fuel, specially if your descend was planed close to the barbers pole. The world has moved on and this is anyhow quite pointless if you are already descending at 250 kts. With this in mind is it not more efficient to plan a descent at iddle thrust (ie delay the top of descent) and minimum rate of descent between constraints until you achive the next iddle thrust profile?
I accept ofcourse that fuel is not the only cost...
Should we not try easier ways to reduce the burn before clogging up all the approaches around Europe?
It makes me laugh all the references of people flying with their head on fire, we are talking about descending at 290kts until FL100 and 250 below. Hardly on fire.
Faro are not so good because they give a short cut? humm... I think a short cut flown at a higher speed will clearly reduce the burn.
In any case the SOP clearly says, again, is the capts decision based on the ATC environment.
Edited to say: you beaten me to it guys!
The most fuel economical descent is not 210 kts (close to minimum sink speed) as we are not trying to remain airborne the longest. The ideal fuel profile is a top of descent for a continuos descent at best glide speed (close to 250 kts) and iddle thrust. The airbus does not plan an iddle thrust continuos descent. It plans a partial thrust descent, followed by a geometrical path between constrains, followed by a level segment at the end. It does this presumably to avoid those peski pilots getting all hot and high and because all those years back it was decided that extra margin was worth the extra fuel, specially if your descend was planed close to the barbers pole. The world has moved on and this is anyhow quite pointless if you are already descending at 250 kts. With this in mind is it not more efficient to plan a descent at iddle thrust (ie delay the top of descent) and minimum rate of descent between constraints until you achive the next iddle thrust profile?
I accept ofcourse that fuel is not the only cost...
Should we not try easier ways to reduce the burn before clogging up all the approaches around Europe?
It makes me laugh all the references of people flying with their head on fire, we are talking about descending at 290kts until FL100 and 250 below. Hardly on fire.
Faro are not so good because they give a short cut? humm... I think a short cut flown at a higher speed will clearly reduce the burn.
In any case the SOP clearly says, again, is the capts decision based on the ATC environment.
Edited to say: you beaten me to it guys!
Last edited by calypso; 7th Oct 2007 at 09:24.
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I don't agree. Managed descent uses a little more fuel in exchange for increased flexibility (for example by including the effects of antice although this is not used in many ocasions and seldom for the whole descent). Thrust iddle descent is more efficient. Open descent would be more efficient if you get it absolutely right. The most efficient would be an iddle thrust managed descent, such as you get if you delay a little the computed top of descent.
Actually the most efficient descent, from a fuel point of view, would be to shut the engines down at TD and descend at best glide speed to a dead stick landing.
Actually the most efficient descent, from a fuel point of view, would be to shut the engines down at TD and descend at best glide speed to a dead stick landing.
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Interesting debate here I suppose, just to add to what I said earlier, and maybe wrap up some issues with the way it came across. Of course the commander of the aircraft (the Captain) is effectively the manager too, that goes without saying from a safely perspective. Playing devils advocate, the company would never stand in the way of a descision made by the captain, esp. safety related.
But, as it's the companys aircraft that he is flying around in, which after all is there for the sole reason of making as much profit as poss....then the management (the earth bound management - bean counters etc) have to at least have their say on how the operation should be run.
The point about taking a 90 degree "off course" is a little dramatic, and not what I would class as a normal outcome to an ATC request for an easyJet to speed up. The Captain had his own reasons for doing that - maybe he was feeling a little bloody minded about the new SOP and took it to the extreme to make a point, who knows...his call.
Cheers Guys....
But, as it's the companys aircraft that he is flying around in, which after all is there for the sole reason of making as much profit as poss....then the management (the earth bound management - bean counters etc) have to at least have their say on how the operation should be run.
The point about taking a 90 degree "off course" is a little dramatic, and not what I would class as a normal outcome to an ATC request for an easyJet to speed up. The Captain had his own reasons for doing that - maybe he was feeling a little bloody minded about the new SOP and took it to the extreme to make a point, who knows...his call.
Cheers Guys....
I, like many think the new econ descent speed is probably to slow in the real world that we fly in. It is easy for some fuel manager to come up with a clever plan while pushing a pen behind a desk that does not work in the reality of a busy TMA.
However, I will fly the new SOP. Not because I am a management clone or cannot think for myself but because I expect everybody else that I fly with to follow it and all the other SOPs that we have. When people start following SOPs that they like and ignoring the ones they don't like nobody knows where they stand. FOs don't know the quirks of every Captain they fly with. With me it's simple, fly the SOP and if ATC want us to fly quicker or the weather is closing in get a move on and apply some good old common sense.
However, I will fly the new SOP. Not because I am a management clone or cannot think for myself but because I expect everybody else that I fly with to follow it and all the other SOPs that we have. When people start following SOPs that they like and ignoring the ones they don't like nobody knows where they stand. FOs don't know the quirks of every Captain they fly with. With me it's simple, fly the SOP and if ATC want us to fly quicker or the weather is closing in get a move on and apply some good old common sense.
Last edited by Airbrake; 7th Oct 2007 at 16:36.
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Cost index 19 descent speed seems to be about 255-265 kts. The difference in time taken to descend at this speed instead of 290-300 kts is 3 mins over a100 mile descent path. At 48 sectors / month that is 2hrs 24 mins / month or about 25 hours a year. That's a week less work per year. Bring it on !
P.S. OTP will now decline even further cos you can bet the fuel boys won't have discussed this with nav planning. Tant pis.....
P.S. OTP will now decline even further cos you can bet the fuel boys won't have discussed this with nav planning. Tant pis.....
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All very fascinating but who was the "Unknown Aircraft at FL70?" I have noticed that all you Lo cost people are descending with a low airspeed, but that was not the issue.
What a can of worms I've opened!
PS, we have a low ci on our aircraft but our sop calls for us to select a higher speed for descent. Oh yes we also taxi on one engine ,after landing, when we remember!
What a can of worms I've opened!
PS, we have a low ci on our aircraft but our sop calls for us to select a higher speed for descent. Oh yes we also taxi on one engine ,after landing, when we remember!
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DD..
It was the same for us too until the last week or so, the CI has been 19 for ages now and we had to pad up the descent speed to 290 kts to "conform" a little more, and yes that was SOP. Now the SOP is to leave it well alone unless...well we've already discussed it to death I think.
Same here with single eng taxi - when WE remember too...
Also, does your company hint as ours that maybe single engine taxi OUT might become another fuel saving panacea?
I really can't wait.....
It was the same for us too until the last week or so, the CI has been 19 for ages now and we had to pad up the descent speed to 290 kts to "conform" a little more, and yes that was SOP. Now the SOP is to leave it well alone unless...well we've already discussed it to death I think.
Same here with single eng taxi - when WE remember too...
Also, does your company hint as ours that maybe single engine taxi OUT might become another fuel saving panacea?
I really can't wait.....