easyJet Cost Index & Econ Descent

[doubledolphins]

Any one able to shed light on the identy of the "Unknown Aircraft" that stopped you all descending and caused some of you to go into the hold? I was departing north-bound enjoying the fun.:rolleyes:

[tubby linton]

It wasn't an A310 doing another airshow was it???

[sarah737]

We had to hold because we were behind two EZY's: the first one doing 265kts in descent, ATC asked the second one if he could fly 320 in order to be number one. He said NO and as a consequence he was slowed down to 220 and we were send in the hold...:hmm:

[clearfortheoption]

Ah! the first effects of the new SOP of flying Cost index speeds during the descent!
It's starting to piss people off already!

[stalling attitude]

It was so obvious that this was going to cause everybody else a headache. The machine wanted us to do 253 kts in descent a few days ago, thankfully ATC wanted us quicker than that.

[bigbusdriver06]

MYT tried that a few years ago, drove ATC mad. Didn't last long. If you hack off ATC, then you can really start using fuel.

[unablereqnavperf]

easy pilots must realise that you are in command and not the machine! I did 6 years at easy and never done what the machine told me to do! If you leave your decent later and decend with thrust idle the speed is irrelevant! common sense and airmanship will always truimph over machinery!

[WaterMeths]

Unable.....

I know what you are saying, and don't think it doesn't cross everybody's mind - but we have an edict from high up that we MUST fly CI in the climb, cruise and descent unless absolutely necessary (ie ATC request) - so just to decide from a simple airmanship view to speed up is not an option now.

This is a new drive along with all the others about saving on fuel costs.

[Airbus_a321]

:{SOP of flying Cost index speeds during the descent! must be close to CI ZERO to get this speed of 265 kts during descend:ugh: Very interesting SOP (Sh..y Ops Procedure):}
Obviously the old times have gone where a skipper had an picture of his air-traffic beyond and behind and so sometimes worked hard to maintain a good, speedy approach flow in favour of all approaching aircrafts.
Quite a lot of the new servile, spineless "machine"-aircraft-movers-generation (I can't call them SKIPPER) seems to fly with VERY BIG blinkers:cool:
"Why shall I care myself about any traffic around me? I feel free like a :mad: bird, and I am the only one flying here and now. Why shall I care if anybody has to join the hold, etc.etc.:mad:

[Dutchjock]

As said before this is now SOP, so I don't think you should direct your anger towards "spineless...skippers" but towards Spineless (or replace with many other censored insults) managers

CI is 19 btw

[Airbus_a321]

Yes, that's SOP.:ugh:
But WHO is the pilot, WHO knows how to fly the aircraft, WHO knows the always different airspace traffic situation. YOU, or the :mad:"SOP"-MANAGER.
I hope nobody will fly the aircraft in the ground, just by to follow any 'sacrosant' S O P.
Start thinking first. Have always some healthy doubts about the mentioned SOP, which are done by still not error-free MANAGERS.
Don't forget that flying, flying in crowded airspace is someting vibrant, something which is dynamic and something which is and which can not be covered 100% by any SOP - just be flexible. That is what you are paid for. Flexible handling of the aircraft e.g. according traffic situation, is what all the skippers around you expect you to do:) Be aware that one day YOU are not number one in the chain, but the guy ahead of you is flying e.g. green dot from TOD - according his SOP.
For just pushing button A during situation B as per SOP number C for me is just monkey business. And is again a defeat for good AIRMANSHIP and good CAPTAINCY etc.:bored:

[Dutchjock]

I agree with you on situational awareness and flexibility. But as nobody else flies around at these silly speeds (as far as I'm aware) the only way of being sensible is to ignore this sop 99 out of 100 times.

why not follow this sop until atc/other operators/ezy pilots make official complaints and this ridiculous sop gets cancelled.

And I thought jets are faster than props...:ugh:

[-8AS]

Heard an EZY Captain refuse an ATC speed restriction (300kts) the other day due "Company procedures". London politely challenged him a number of times before turning him 90 degrees to the airway to allow faster traffic behind through. Can't see how that saved EZY any money. Will also waste some administrators time at Orange HQ when the ATC report lands on their desk.

[J.O.]

Get used to it folks. As the price of fuel climbs ever higher, and as the pressure to reduce carbon outputs rises, more and more carriers will be flying at a lower cost index. My company started doing it about a year ago and our fuel usage has dropped by 3 to 4%. If ATC asks me to go faster in descent, of course I comply, but otherwise, I realize the extra bit of time it adds to the flight is saving ALOT of money, even with the increase in airframe time that comes with it.

[Flyit Pointit Sortit]

airbus a321

Just curious, which other SOP's do you ignore??

I would appreciate a little more respect from fellow aviators as to thinking that we are mindless zombies demonstrating poor airmanship.

Don't think for a second that this policy is popular amongst the flight crew. But sometimes you need to "work to rule" to prove a point. If as a result of flying this speed I have to slow an aircraft up or send another to the hold, be in no doubt that I will fly a suitable speed and file an ASR.

Hope that the aircraft that got sent to the hold MORs the ocassion and Ezy managment have to explain the policy.

[F4F]

unablereqnavperf
easy pilots must realise that you are in command and not the machine!

Well, the problem is not with the machine, but with management... which by the way is also in command, not directly of the aircraft (anyway, who of you guys can pretend to be in command of an Airbus :E) but at least of my position within the airline.

One way to increase the speed given by the CI 19 and save even more fuel is very late descent, but beware :cool:


live 2 fly 2 live

[Hank Birofski]

Yes - I'm disappointed if crews are refusing to increase speed at the request of ATC. The SOP allows for tactical speed intervention in such cases and doing so would be good airmanship.

F4F - that's a negative. You will use more fuel as the engines stayed at a crz pwr setting for longer.

[doubleu-anker]

A big part of airmanship is to "work in" with ATC, within safety, to facilitate the smooth and orderly flow of air traffic.

Some of the robots at ez don't seem to be doing this, judging by the first post, on this thread.

The old saying "you can teach a monkey to ride a bike but you will never teach it to read road signs" comes to mind.

[Bokkenrijder]

Yes, perhaps lot's of pilots in eJ are spineless, but what do you expect from people so gullible that they blindly accept all the cr@p (just look at all those NTC's regarding fuel... :rolleyes: ) that is dumped on them by this beloved "Penny wise, Pound foolish" management?

Keep on bending over!

[Bealzebub]

The answer lies in what is an SOP ? It is a Standard operating procedure. I don't think it is a case of picking and choosing which of these procedures you will adopt and which you will ignore. Rather it is a case of recognising that there are situations which may well require a modification to the standard procedure, simply because the situation you find yourself in, is in itself not standard.

Compliance with an ATC request or instruction is usually born out of an obvious requirement. Every flight submits a flightplan with its cruising speeds an integral part of it. Variations are normally issued to ensure safety is not compromised or as part of that, the airspace block being efficiently utilised. Unless a request is simply being offered as a courtesy, or unless there is a safety issue ( turbulence penetration, likelyhood of an unstabilised approach etc.) such an instruction should not normally be compromised simply to comply with a companies standard operating procedure.

If an SOP is likely to cause difficulty or complications for ATC and other air traffic, it is at the very least incumbent on the Captain to ensure that ATC are given the information in a timely manner that ensures they can make adjustments to cause the minimum amount of disruption to both themselves and other traffic.

Every airline employs standard operating procedures for standard and some emergency situations. Every airline places a high commercial importance on minimizing its own operating costs. However every airline also selects its pilots and certainly its operating Captains to do what the FMC and the manuals can't. That is apply discretion, discrimination, judgment and common sense to any given situation.

[PENKO]

Yes it is SOP to fly optimused speeds, but the SOP clearly states that it can be overruled by ATC-requests!

So how does that fit in with this topic?

[Check Airman]

We had to hold because we were behind two EZY's: the first one doing 265kts in descent, ATC asked the second one if he could fly 320 in order to be number one. He said NO and as a consequence he was slowed down to 220 and we were send in the hold...

If that's so,those pilots are very selfish indeed. He must be telling himself "Let me save 50kg of fuel even if it means each person behind me burns an extra 500kg. I'll be able to sleep at night because my boss, who sits behind a desk all day thinks that's how it should be done."

People, there's a reason WE are in command. I for one wouldn't hesitate to ignore the CI speeds if it means a more expeditious flow of traffic. I don't know about these guys, but I'd feel pretty bad if I caused somebody else a major inconvenience (hold or missed approach), especially for something as trite as that. Come on guys, please display professional courtesy and good airmanship.

[snooky]

Rather than speculate about the fuel savings available why not try a scientific test.
Takes a few flights to complete, but gives interesting results.
I have found that the difference between a 40CI descent (often around 260 kts) and a 300 kt descent is around 100 kg.
This has been calculated by noting the cruise fuel burn (must be stable), the descent fuel burn and the extra time spent in the cruise for a 300 kt descent as opposed to a 260kt descent. The time saving of the higher speed is less than a minute (and is at idle).
40 sectors a month gives a saving of 4 tons, which I may be wrong but thinkm equates to $3200.

Similar savings are achieved by cruising economically.

Green issues have been afforded much greater importance in recent times, so policies such as that at EZY will become the norm soon, it wil be the 340kt merchants who find themselves being vectored.

Do the controllers vectoring us towards the hold at high speed realise the size of their carbon footprint? :8

(By the way, I think it's down to form drag increase)

[Watchdog]

I-FORD,
you may want to look up the definition of Cost Index in your aircraft's FMC/FMGC manual. :uhoh:

[Bokkenrijder]

Oh and let's also look on the bright side of the latest wet dreams of this fumes, errrr fuel/carbon footprint madness: imagine all those extra block hours and how quickly you will reach those 900 hours! On top of that, imagine the effect it will have on OTP and therefore (the already closely planned) the max daily duty limit. Lemme guess: going into discretion seems will be the only 'authority' that will stay in place for a while...

I guess then next move will be to increase our annual maximum to 1000 hours and perhaps do away with alternate fuel or a further reduction of contingency fuel. Big Brother, in his cozy office, is already checking the weather and NOTAMS in those trip envelops to see whether those 500kg extra for TS's were really justified or not. All in the name of "safety?" Who needs fuel anyways?

How low can you go? :{

[LYKA]

I guess they didn't read the 10-9 chart entitiled speed control under radar and then look at the NTC!:ugh:

[Denti]

We tried the same thing in the last few years. Although we used repetitive flightplans that are only filed twice a year (one for winter and one for summer) we changed our cost index quite a bit from around 35 down to between 12 and 16 and were reminded to allways fly CI, which turned out to be around 250kias during descent (737 classics).

One thing we noticed right away was that the working environment became much more quiet and bearable reducing our stress level quite a bit, another thing was we got payed more since we our pay was based on actual block time.

Very soon our operation team had to change the policy a bit allowing us to use our own judgement for descent since ATC just couldn't really work with that, every descent out of cruising altitude actually reduced our speed immediately quite a lot (usually around 30 to 40 kias or .20).

Now we get payed a fixed amount for each sector regardless of how long it takes to get there and many of us just fly close to red line, who cares about fuel since we're purely operating as ACMI anyway.

[RAT 5]

I would question the comment that SOP's are rigid and gospel. I've flown for too many operators whose SOP's changed with every change of Chief Pilot. They each had their own favourite way of doing things. Some were good ideas, some were crass. Common sense/airmanship should always prevail. That's what we are paid for.
There was one C.P of a London based Loco, who demanded Gear down at G/S alive. What a classic way to waste fuel. Had he never heard of Low Drag. low noise, low fuel approaches? Then the London Airports demanded these type of approaches, which most of us had been flying anyway at every airport for decades. Guess what, the SOP's changed to suit ATC.
As for C.I's. I thought that zero was min fuel. Also, I did fly for 1 operator who tried the Boeing ideal that C.I. should be selected for each sector dependant on fuel % price; i.e. a variable. What a fisco that was. LRC seemed to work fine for most trips.
I heard it said that ej's first B737 C.I was chosen to match Stelio's age. If correct, how scientific was that.

[OBK!]

i-ford

no matter what speed you fly in the descent, econ speed given by a cost index worked out by the company is the most economical...that's what cost index is all about, trading cost of time between cost of fuel. i'm not one for slow descents but if it keeps me in a job then i'll do it where possible.

[slip and turn]

As a non CP I am intrigued by these various descent SOPs. I was in a 737NG yesterday which went for fast descent overall (about 25 mins from start of descent from FL380 I guess to touchdown - 8000/25 = 320 I note), it had been assigned a very long more or less straight in approach, with speedbrakes deployed for at least the last five minutes right up to the point of first stage of flaps and slats.

I have over the last year or two also noticed a number of complaints by afflicted aircrew in the medical forum here on PPRuNe asking about repressurisation problems with their ears.

Now are descent profiles like that usual or unusual thesedays? And are you saying that such descents are believed or found to be less economical than at first thought?

[easy]

and if everyone else flew CI 19 on the bus or 26 on the 737 then we'd all save a shed load of fuel and not get our knickers in a twist about someone flying 12 kts slower than us!:ugh:

[F4F]

Hank Birofski
You will use more fuel as the engines stayed at a crz pwr setting for longer
Yeah well, it doesn't really work this way, does it?

1) u sure wanna stay at those cruise level as long as possible, as these are the ones where u burn little fuel
2) if u fly the bus, u will have observed that following a profile descent, despite the IDLE FMA indication, still gives you some thrust (look at the N1 or EPR depending on engines) during the descent, thereby burning thrust to keep those misery 251kts (its what we had last nite...).

Conclusion: to save fuel climb as quickly as u can to the cruise level and stay there as long as u can. And if permitted, descend as steeply as u can, ideally switch the engines off :ok:
Remember, jet engines are optimized for hi level cruise, not lo level loitering :cool:


live 2 fly 2 live

[HundredPercentPlease]

As usual, a lot of rubbish spoken here.

According to Airbus (if anyone could be bothered to read the document), the 319 saves 1 Kg of fuel per knot reduced in the descent (260kt to 300kt range).

If you perform an intermediate level off, the descent speed may well drop from 275 ish to 255 ish.

The SOP allows speed to be specified by ATC, or indeed the commander may choose a suitable speed for the ATC environment. Sounds like some Captains are not doing either!

[Denti]

Denti,


Quote:
Now we get payed a fixed amount for each sector regardless of how long it takes to get there and many of us just fly close to red line, who cares about fuel since we're purely operating as ACMI anyway.

Nice to see your company value a bit of commercial awareness amongst their pilots. Guess it shows not everyone shows the same level of professionalism.

Well, we're still payed block time, however a fixed amount for each leg, so called standard block time, no matter how long it takes. So why take longer than you get payed for? And no, my company doesn't pay the fuel, the company that leases us does (ACMI just includes aircraft, crew, maintenance and insurance), my company couldn't care less.

[square leg]

Cindex = Ctime/Cfuel

To get a better picture of the whole thing read:

http://www.iata.org/NR/ContentConnector/CS2000/Siteinterface/sites/whatwedo/file/Airbus_Cost_Index_Material.pdf

SOP = Standard Operating Procedures (I think). So whilst most phases of flight(s) are standard, some might not be and thus a modified descent speed might have to be used (i.e. selected).

Or, looking at it from a different angle, going to certain airports, it is SOP to fly such and such a speed in the descent to comply with ATC requirements. I'm sure that complying with (good) ATC is part of most of our SOP's.

Obviously if your descent profile (descent arrow) is based on CI 0 (low) i.e. early descent and you initiate your descent based on that and fly the managed speeds associated with that CI and are then asked to fly high speed, you will burn more fuel than originally computed by the FMGC.

The way I understand it, for a given CI, there will always be one (1) optimum point of descent (for a given profile on a perfect day). For that specific CI, descending before OR after that point you'll burn more fuel.

BUT, we don't live in a perfect world and thus I think we should try and be as close to SOP's as possible, but have enough flexibility (in our minds) to accept deviations from these same SOP's, knowing that we will return to SOP when appropriate. Part of SA is not only knowing where we were 1 minute ago, where we are now and where we will be in 1 minute, but also knowing who is around us and how we can contribute to a most efficient way of operating to assist all parties involved (aircraft & ATC). (SA involves much more obviously...)

[Few Cloudy]

If your cruise and descent management saves fuel vis a vis the flight plan - and mine usually did, then I can't see how the slow descent scenario can ever be better.

It is a very short sighted policy to save theoretically peanuts in descent and end up in a long approach at low level anyway.

The true saving occurs with the latest possible idle descent - even though the speed comes up over your "optimum" FMC or book speed - and into an expeditious approach.

Coming up from the south to LTN you can often get a left hand descent straight into RW 26 and if you do it right, hardly touch Stanstead airspace - gaining anything up to 450kgs and many minutes a shot. Follow your FMC routing and descent on this one and you lose - every time.

The fact that flying slow cocks up your colleagues - possibly from your own airline, makes this individually calculated policy even more daft.

Bottom line, pilots have more flight experience than FMC computer designers - use it!

FC.

[sidestickbob]

It's a lot more civilized when everyone does 290Kt in the descent. I bumbled into PFO the other week behind an Airbus that I'm sure was taking part in a slow flying competition - I think it won too! I'm not slagging off the Airbus (I fly one too) but some of the descent speeds it generates are rediculous. Selected speed - way to go, unless ATC tell otherwise of course.:)

[Wingswinger]

It would all be solved if everyone involved took the trouble to re-read the new SOP carefully, word by word.

[Max Angle]

We use CI 15 in our 320/319s and descent speed is often 250 knots which is far too slow to fit in to the general ATC environment (mind you it would work if everybody used it) so most people tend to use 280 which apparently makes no difference at all to the overall CI cost/time/fuel calculation. To make that work though you need to re-program the descent before you start down to show 280 knots. Going down at the 250kt top of descent and then selecting 280 and getting low or using v/s to stay on the profile is very inefficient.

As topslide says the whole slow descent thing is based on the fact that you spend less time in the cruise using fuel because the descent starts a few miles earlier but the number of times you are asked to speed up or get a few extra miles added to your track because you are put behind other traffic means that overall I am quite sure that entering a slightly higher speed makes good sense. There is no doubt that we have saved fuel by using a lower index but mainly due to slower cruise and taxing in on one engine, slow descent is not saving much at all.

[MorningGlory]

good point.. how many of you taxi in on one engine? is it generally approved of in your company, or is it an sop? what do you think? thoughts/comments please :}

[A4]

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. :confused:

Fly safe everyone.

A4

[Bad Robot]

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.

[Shiny side down]

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.

[Just Browsing]

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

[Rananim]

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.

[Green Guard]

Saving fuel may be just a smoke screen for a L O N G E R duty time,
hopefully peanuts paid overtime etc. etc.:}:}:}

[Right Way Up]

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.

[A4]

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 :hmm:

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

[PENKO]

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..

[Right Way Up]

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.

[PENKO]

Their time and effort would be better spent trying to debate and explain the new flap 3 landing regime :}

Now that's a challenge.

[Right Way Up]

Oh now you've done it........

[calypso]

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!

[LYKA]

calypso - Managed Descent vs. Open Descent. Managed Descent is more efficient.

[calypso]

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.

[WaterMeths]

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....

[Airbrake]

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.

[autobrake3]

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.....

[doubledolphins]

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!:ok:

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!

[WaterMeths]

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.....;)

[Ashling]

Calypso, don't even suggest it !

As others have mentioned the SOP clearly states you can alter the speed for tactical reasons or at ATCs request. So people refusing an ATC speed request using company procedures as an excuse either struggle to read and comprehend a simple notice to crew or are just pig headed. I rather suspect a number of them haven't even bothered to read it and just relyed on a mate saying "have you seen that NTC that says we have to descend in Econ"

The SOP does not rob the Captain of his authority and gives him discression to adjust the speed if he judges it prudent to do so. Clearly in a busy TMA or other traffic environment it would be appropriate to do so. However if its quiet what is wrong with drifting in at Econ and saving some gas ? Maybe people just lack SA.

In any case the SOP is what it is right now. I'd have rather it said when possable descend in Econ instead of making it the default but there we go. So until it changes we respect it, and maybe it will change if it hacks off ATC too much or enough crews raise concerns and back them up with reports. If you don't like the SOP the correct course is to raise your concerns with the author of it, file an ASR etc. Declaring independance and doing your own thing is not the way forward.

[Over+Out]

Pilots, please answer me this question from a TC Controller.
If you wish for economy, lets say on a LAM SID from 26L at KK. Is it better to go for economy and still be at 6A at BPK or go for a max rate of climb and be above FL130 by abeam LL going north so that we can jump the stacks?

[E. MORSE]

Over+Out,

For economy, and to help ATC out, best thing I think is a fast climb to get the early left turn northbound.

We can do that by keeping speed at 220 (after the LAM turn with lower speed for the radius anyway) in stead of increasing to 250, and +/- 290 above FL100.

Thing is it needs some local knowledge, and it is probably only "valid" for the example you mentioned, all the rest is standard acceleration.
You probably cannot hang this on a piece of paper in a crewroom.

[Right Way Up]

Over+Out,
Most times the early left turn is preferable and achievable. "Higher" clearance with expedite should work.

[A4]

O+O,

I'd prefer the straight climb to FL130. I think stooging around at FL60 still at BPK would be a lot less efficient. Depending upon time of day, I try to get to FL160 to get over the BNN stacks when I'm heading south to SAM/SITET (out of SS not KK!). Doesn't always work out - but seems to more often than not.

A4

[LYKA]

Calypso - It is cheaper to initiate a descent slightly early than late. It is always possible to reestablish the proper profile by making an early correction to the descent profile at a high altitude. If the descent is started late and the higher descent speed cannot burn the excess energy, then the energy has already been consumed at altitude and the speed brakes will most likely be required during descent.

[HundredPercentPlease]

A CI 0 descent (.764/252/250) uses 138 Kg and takes 19 mins.

A CI 20 cruise from the same starting point, and then descent (.779/278/250) uses 157 Kg and takes 17.8 mins.

And a CI 40 cruise from the same starting point as the CI 0 case, then descent (.786/311/250) uses 187 Kg and takes 16.8 mins.

[SpamCanDriver]

Unfortunately you guys at easy aren't the only ones, we at T-Fly now have the same stupid descent speeds aswell!:mad:

[A4]

Thanks for that Hundred%. So if EZY save 20Kgs per flight on 80% of their flights that's about 110 tonnes of fuel or about $70,000 per month at $600/tonne.

Of course if they save 30Kgs on 100%..............

You can see where they're coming from I guess.

A4

And so it comes to pass.... TFly are the first to follow suit.

4

[HundredPercentPlease]

A4 - don't forget to subtract the extra cost of maintenance incurred by the longer sector times. Easy's own figure is that the net saving will be £200k a year (if every sector is flown like this), enough to pay just one fifth of one man's bonus. :rolleyes:

[LYKA]

100%...Nearly, time dependant maintenance costs (TDMC) are included in the CI calculation.

[HundredPercentPlease]

Lyka, I know. They are used to calculate the optimum CI. But A4 calculated the total saving by just looking at the reduced burn, when you really need to then subtract the extra TDMC incurred.

[Ashling]

Greater average flying time due to slower descent speeds = less days on duty and its all at the companies behest. Fantastic.

[Right Way Up]

And less noise on the flight deck during descent. :ok:

[Vmike]

I don't fly an Airbus so I wouldn't know, and I guess a 737 is different, but just how do the beancounters know what CI and speed you choose to descend at?

[mabrodb]

If everyone operating new equip. types, e.g. the Minibus' (A318~321) and 737 NG’s actually knew how cheap the Time-Dependant-Maintenance-Costs (TDMC) for their actual eqp was (in the $300-$400 USD/hr range for most factory fresh jets)..most operators would be operating in the C/I 10~20 range, and everyone would be planning/flying slower (closer to max L/D) econ descent speeds, causing smaller issue w/ ATC.
Alas, since most operators have no clue on what it actually costs to operate their machines, they guess. Or better yet, ask some a chief pilot for a selection of figures pulled from a hat, hoping they are close to the cost optimal descent speeds, which would be true, if fuel was cheap and maintenance costs where high (think Tridents and 727’s), then everyone, including ATC would be on the mark.
The real issue is, we have operators who have somewhere between a small clue and no clue at all, on what the time dependant costs to operate are.

[calypso]

Just guessing here but for equal deviations from the ideal descent profile to be high seems better (in fuel terms) because you have burnt the extra fuel up high where the engines are more efficient rather than lower where the specific fuel consumption is higher.

Five miles more at FL350 burn a lot less than five miles more at 3000 feet. In any case with our descent speeds you have to get it very wrong to not be able to correct the path by speeding up. Afterall this days you can increase your speed in the region of 90 kts form the planned descent speed. At the same time there is no margin to slow down if you are low, as you are already very close to best glide, you will have to add thrust to maintain the profile, the higher you do that the most efficient it is.

[albertoli]

Bokkenrijer

As usual nothing consrtuctive to say moan moan. I take it you do not work for easyjet but if you do you really should think about leaving and take your p**s poor attitude with you.

My mate works for easy and he seems quite happy with his lot. He also tells me that if ATC ask you to go faster then you can, so just tell them and hopefully they will. Captains that refuse to increase speed are just being obstructive.

[countdownconundrum]

I work at easy.. of course we should be flying at speeds requested by atc! easyjet prefer econ speeds in the descent, however, if by atc request at certain speed, well fine. I think some of the poms are giving their command away to the machine!!

Upsetting the flow of traffic is not fuel effient as atc will no doubt modify ur routing accordingly! Since the new sop, I have asked atc what speed they would like and flown it. otherwise no speed equals econ speed.

[theloser1]

From easy NTC.

Flying the Cost Index is a company policy, and is not a crew discretionary item. Deviating from the dispatched Cost Index may only be done if required by ATC or charted procedures or if in the judgement of the captain, the current ATC environment dictates a higher descent speed.


The Cost Index applies to ALL flight phases - climb-out, enroute, and descent.

From the above I read that there is commanders discretion to deviate from company policy. Common sense should prevail

[sky9]

This idea comes up every time there is an increase in fuel costs. The problem is just putting in the cost index doesn't give you the best TOD. Without accurate lower level winds it all become a bit of a guess. The advantage of using a speed higher than optimum is that the fuel miles incurred at higher level are better than the same expended at low level.
Experience in the past has shown that if you set off with a slightly higher speed you can come back towards optimum to maintain idle thrust if the winds or ATC routing bring the aircraft below the optimum.
The whole process disappears out of the window when ATC say "Take up the hold".
The idea is one beloved of accountants who know the cost of everything but the value of nothing.

[78deg]

Tfly and Easy are using CI which produce descent speeds just above 250 kts, the only problem with this is that other airlines are using faster speeds. There is no doubt that these lower CI are to save fuel and it is a significant amout. As has been said elsewhere TFly and Easy are setting the lead here and as time passes the old higher speeds will become less common. At the moment when ATC control decsent speeds they are generally around 290-300 kts, ie 300 or greater or 290kts or less, the reason for this is because this is the percieved optimum speed. However as more opperators work on fuel saving maybe 260kts will be percieved as the optimum speed by ATC. I predict that the UK ATC enviroment will catch on to this first.
To those who say this has been done before (low cost index ) I agree it has, but in the past it has just been for fuel cost, now as well as that there is the desire to reduce carbon emmisions, which will be more powerful.

[PPRuNe Radar]

Just to throw one red herring back in to the sea ..... filed TAS is irrelevant as it refers to cruising TAS, climbing and descending aircraft are likely to be flying something slightly different.

As a controller, both TMA and at nose bleed levels, here's what goes through my brain cells:

First off, where are the inbound aircraft in relation to each other ?

If someone is 10+ miles ahead or on his own, then there's no need for ATC intervention. I'll monitor.

If there's 2 or more between say around 8-10 miles apart, then I'll use experience to judge whether speed control is needed or not. I'll look at aircraft types and use a bit of that experience to assess if I need speed control or not. If I do, then I'll want the guy ahead to be faster and the one(s) behind to be equal or slower. If I'm not sure, or can't provide constant monitoring, then I'll tell you the speeds to fly.

Under that, I'll be setting the speeds or providing vectors or vertical separation.

Additionally, if someone at the front can't fly fast, then I'll assess how far to go and what class of aircraft are involved and come up with a plan (turboprops CAN fly relatively high speed close in, so if less than 60 miles from the field, the jet ain't gonna win, sorry folks). That might mean the slow aircraft being vectored outside the sequence to let the fast ones in, all in the name of expedition.

There are no hard and fast rules, other than ATC wanting to have a nice easy plan which satisfys safety and then expedition.