EZY Captain gets the boot
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For the pedants, assuming your airline has done the analysis and considered the fuel related costs and time related costs, moving away from the official CI in either direction, will increase the total cost of the trip...thats the point.
Once in the descent, the burn is the same regardless of speed...have a look at the FF and see if there is an appreciable difference dependent on speed...
If you arrive at TOD with a certain amount of energy, you've got a choice about how you dissapate it.
The difference between idle descent and stabilised final approach FF on the 73 Classic is ~2400kg/hr...from memory. Thats about 40kg/min.
Therefore if your thrust levers are coming up more than 2.5 mins i.e., ~7nm prior to the 1000 AAL gate, you've just cost yourself >100kg of fuel...
My guess is that is where the extra burn derives its origin from as I know very few pilots who, even when given the opportunity, can consistently arrange their descent with such precision.
Maybe the EZY skipper concerned was trying to?
I have to say, as a crew we've stabilised below 500 RA, filled in the paperwork and still have jobs...
Once in the descent, the burn is the same regardless of speed...have a look at the FF and see if there is an appreciable difference dependent on speed...
If you arrive at TOD with a certain amount of energy, you've got a choice about how you dissapate it.
The difference between idle descent and stabilised final approach FF on the 73 Classic is ~2400kg/hr...from memory. Thats about 40kg/min.
Therefore if your thrust levers are coming up more than 2.5 mins i.e., ~7nm prior to the 1000 AAL gate, you've just cost yourself >100kg of fuel...
My guess is that is where the extra burn derives its origin from as I know very few pilots who, even when given the opportunity, can consistently arrange their descent with such precision.
Maybe the EZY skipper concerned was trying to?
I have to say, as a crew we've stabilised below 500 RA, filled in the paperwork and still have jobs...
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Totally agree with you as far as you go Blackbird but remember, in the descent it is Fuel FLOW that is the same, but at slower speed the descent lasts longer (therefore a small increase in TOTAL DESCENT fuel burn in a slow speed descent) but that extra fuel burn is more than saved by starting the descent earlier than you would for a hi spd descent - thereby saving the fuel that would otherwise be burnt with the thrust levers at crz power prior to TOD for a hi spd descent - a significant net fuel saving. The whole point is that the position of TOD is affected by planned descent speed. At a planned Hi spd descent you have already burnt your 'extra' fuel prior to TOD. Ergo, planned slower speed descent = earlier TOD point = less time spent with crz thrust applied = fuel saving. Total cost is a different argument completely. For instance, tankering fuel. We do it to save money but it costs extra fuel.
Last edited by BANANASBANANAS; 15th Jul 2008 at 13:05.
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Without wishing to further hijack the thread, total cost is exactly the point of the argument in this day and age....
Speeds should be adjusted via use of the CI to reduce trip cost to the minimum. The speeds the CI throws up are incidental to the argument.
Having reached the CI computed TOD point and started your descent, if you choose to adjust the speeds, what happens to the total burn from that point on?
Speeds should be adjusted via use of the CI to reduce trip cost to the minimum. The speeds the CI throws up are incidental to the argument.
Having reached the CI computed TOD point and started your descent, if you choose to adjust the speeds, what happens to the total burn from that point on?
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Having reached the CI computed TOD point and started your descent, if you choose to adjust the speeds, what happens to the total burn from that point on?
End of the day, Plan the flight sensibly/practically and try to fly the plan. Of course I agree that total cost is important (though the tree huggers might argue wrt tankering which saves money but burns extra fuel) but I was responding to a specific question/comment about fuel burn, not total cost.
Min fuel burn = max time at idle thrust in descent!
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http://www.boeing.com/commercial/aer...7_article5.pdf
Article for all you armchair experts on Cost Index . . .
Article for all you armchair experts on Cost Index . . .
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Is this not all largely academic (especially in relation to a skipper getting the sack)?
I understand the theory behind low CI, early descents and the rest - but to work properly it requires an idealised non or low traffic environment. The realities of airspace structure and traffic often render these early descents less efficient than might be imagined.
Get the earliest possible descent a couple of hundred miles out the second you're prompted by your box? Fine. They just let you down a couple of thousand feet and hold you there. With the end result you're spending time lower down than you otherwise would have, burning a little extra fuel and a hole in your heart. It's a net loss.
It's an idealised solution and you have to account for the environment in which you find yourself. Controversially, this would require some awareness and perhaps even some thought. Given that one can't magic away the traffic, and that you're looking to save a few drops of fuel, would it not be more sensible to descend - yes, at the slowest speed and at the earliest possible - at the earliest point at which you're likely to be able to complete the descent and arrive at the last possible moment? It's not necessarily where the arrow sits on the line.
I understand the theory behind low CI, early descents and the rest - but to work properly it requires an idealised non or low traffic environment. The realities of airspace structure and traffic often render these early descents less efficient than might be imagined.
Get the earliest possible descent a couple of hundred miles out the second you're prompted by your box? Fine. They just let you down a couple of thousand feet and hold you there. With the end result you're spending time lower down than you otherwise would have, burning a little extra fuel and a hole in your heart. It's a net loss.
It's an idealised solution and you have to account for the environment in which you find yourself. Controversially, this would require some awareness and perhaps even some thought. Given that one can't magic away the traffic, and that you're looking to save a few drops of fuel, would it not be more sensible to descend - yes, at the slowest speed and at the earliest possible - at the earliest point at which you're likely to be able to complete the descent and arrive at the last possible moment? It's not necessarily where the arrow sits on the line.
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5150,
Oh please, that link is only 3 pages long.
Why not this one: SmartCockpit - Airline training guides, Aviation, Operations, Safety
Its 108 pages long.
Caudillo,
Absolutely agree. We're talking ideal world here. In reality, I personally think its best to stay high for as long as possible because chances are if I'm track-miles challenged, and ATC can see that, I figure I'm less likely to be held up at low level.
My $0.02.
Oh please, that link is only 3 pages long.
Why not this one: SmartCockpit - Airline training guides, Aviation, Operations, Safety
Its 108 pages long.
Caudillo,
Absolutely agree. We're talking ideal world here. In reality, I personally think its best to stay high for as long as possible because chances are if I'm track-miles challenged, and ATC can see that, I figure I'm less likely to be held up at low level.
My $0.02.
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How about speedbrakes?
If speedbrakes are used in decent, that means there is fuel wasted earlier in cruise, so if the decent is planned carefully and optimized, no speedbrake should be used.
This also increases comfort for your paying passengers, as it feels terrible in the cabin with speedbrakes extended. (IMHO)
I personally prefer to decent a bit early, there is always a chance for a nice shortcut and technically, it is much easier and safer to add a little thrust then destroying energy, be it altitude or speed, with extra track miles or speebrakes or some other manouvers.
If speedbrakes are used in decent, that means there is fuel wasted earlier in cruise, so if the decent is planned carefully and optimized, no speedbrake should be used.
This also increases comfort for your paying passengers, as it feels terrible in the cabin with speedbrakes extended. (IMHO)
I personally prefer to decent a bit early, there is always a chance for a nice shortcut and technically, it is much easier and safer to add a little thrust then destroying energy, be it altitude or speed, with extra track miles or speebrakes or some other manouvers.
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Is this not all largely academic (especially in relation to a skipper getting the sack)?
Over to Tech Log if anyone wants to continue the semantics of descent planning?
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And why are you asking for 160 to 4 when the next traffic is 20nm behind you and there is nobody in front or to depart????
A) Because its the "law"...or rather in its MATS 2 local operating instructions.
B) There may be nobody in front or behind you or no departures but you flying 160 to 4 means the tower know exactly how much time they have to do, for example, a runway inspection/cross a towing aircraft/route a VFR heli through the overhead etc etc etc.
LYKA.
Please answer this. You are in the cruise at FL370 and are really tight on fuel.
Assuming an optimum descent profile which would get you on the ground with the most fuel remaining with the same starting Mach No.?
1. 250 IAS
2. 300 IAS
Please answer this. You are in the cruise at FL370 and are really tight on fuel.
Assuming an optimum descent profile which would get you on the ground with the most fuel remaining with the same starting Mach No.?
1. 250 IAS
2. 300 IAS
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Airbrake, I would not know exactly but I would bet 250Kias.
I was stitched this morning, an aircraft decided to fly 180Kias from approximately 20-25 track miles from touchdown. This incured a penalty to me (no.2 behind) and the four aircraft behind in the sequence.
My point is nothing to do with which CI or which speed is best but airmanship/professionalism. When someone is flying slower it will inevitably cause a bottleneck and result in a fuel penalty. (I could not care less about the 1 or 2 minutes extra flying time)
I try and keep the thrust levers closed from TOD to four miles as much as possible - this in my opinion burns the least amount of fuel. I dont roar around at 320Kias + and I do ok.
For the sake of argument and this thread if Ezy want to plan for a slower descent, no problem
I was stitched this morning, an aircraft decided to fly 180Kias from approximately 20-25 track miles from touchdown. This incured a penalty to me (no.2 behind) and the four aircraft behind in the sequence.
My point is nothing to do with which CI or which speed is best but airmanship/professionalism. When someone is flying slower it will inevitably cause a bottleneck and result in a fuel penalty. (I could not care less about the 1 or 2 minutes extra flying time)
I try and keep the thrust levers closed from TOD to four miles as much as possible - this in my opinion burns the least amount of fuel. I dont roar around at 320Kias + and I do ok.
For the sake of argument and this thread if Ezy want to plan for a slower descent, no problem
Eagerbeaver you are right the answer is 250kts. Once you have started any descent at a pre planned speed if you then have to increase speed you will burn more fuel because of the simple fact you will gradually go low on the pre planned profile and have to increase thrust at some stage.
I think some people here are showing some confusion about the implications on total fuel burn with changes of speed in the descent.
I think some people here are showing some confusion about the implications on total fuel burn with changes of speed in the descent.
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Yawn...
Except for a few people, most seem to miss the point of this whole thread and instead prefer to be distracted by trivial details like 160/4, Cost Index, use of speedbrakes etc... 
Doug the Head;
Yep, and I'm outa here; there's no further point.
The whole point is the firing of a veteran airman using what is supposed to be a safety tool. I would like to have seen contributions from those who have agreements in place, how such agreements are respected/handled, what new endeavours might be derived from FDA programs, (we have the capability of enormously detailed analysis of fuel-use including single-engine taxi's, fuel used while waiting at the gate for the ground-crew, as well as all phases of flight). The paucity of imagination is disappointing but hey...it's an anonymous rumour network not a collegial setting where common interest must focus towards anything specific. The distractions on this thread mirror the way most discussions tend to go. Hopefully a few derived benefit.
Cheers.
most seem to miss the point of this whole thread
The whole point is the firing of a veteran airman using what is supposed to be a safety tool. I would like to have seen contributions from those who have agreements in place, how such agreements are respected/handled, what new endeavours might be derived from FDA programs, (we have the capability of enormously detailed analysis of fuel-use including single-engine taxi's, fuel used while waiting at the gate for the ground-crew, as well as all phases of flight). The paucity of imagination is disappointing but hey...it's an anonymous rumour network not a collegial setting where common interest must focus towards anything specific. The distractions on this thread mirror the way most discussions tend to go. Hopefully a few derived benefit.
Cheers.
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Maybe the 'veteran' airman was fired because the safety tool did its job?
As has been mentioned on here, this does not appear to have been an isolated incident. If so, then the system would appear to work. I have been a 'victim' of FDM - and whilst it seems an intimidating process at first, I discovered the attitude within EZY to be constructive and focussed on training, not punishment - but I was left in no doubt what the outcome would be if violations are persistent or negligent. (My incident was high speed below 500', but during a low go-around with flap problems - FDM didn't tell the whole story and our report was an adequate resolution)
There is no way that any EZY pilot could claim ignorance of the emphasis which the company puts on the stablised approach criteria, especially if they had already experienced the 'system'. There is always the option to go-around at 500' - if not, then one is already at a point where a MAYDAY call should be considered. To all those who have remarked that avoiding a go-around even though 'a little bit' unstable saves fuel (and hence costs) - EZY is not the only company receiving a massive insurance premium reduction on the basis of the 500' policy, and associated proven flight safety benefits.
If it is recognised, as by some folks on here, that Flap 3 approaches are often a little more 'slippery', then surely the answer is a no-brainer: plan to begin configuring earlier (with advice to ATC if under proessure to keep high speed - I have never had any grief from ATC by giving them timely notice of extra track miles or speed reductions required, even in France!). Some of the posts on here crying 'airmanship' or going on about the divine right of the pilot to ignore a clear, safe, straightforward company policy smack more of ego than an attempt to operate in the safest possible manner.
I will keep my aircraft safe, but once that is achieved - it's not my train set, and I will operate how I am required to by my boss.
(btw, don't our training dept and management get some credit for their 'experience', in the same way that this individual is assumed innocent because of his?)
As has been mentioned on here, this does not appear to have been an isolated incident. If so, then the system would appear to work. I have been a 'victim' of FDM - and whilst it seems an intimidating process at first, I discovered the attitude within EZY to be constructive and focussed on training, not punishment - but I was left in no doubt what the outcome would be if violations are persistent or negligent. (My incident was high speed below 500', but during a low go-around with flap problems - FDM didn't tell the whole story and our report was an adequate resolution)
There is no way that any EZY pilot could claim ignorance of the emphasis which the company puts on the stablised approach criteria, especially if they had already experienced the 'system'. There is always the option to go-around at 500' - if not, then one is already at a point where a MAYDAY call should be considered. To all those who have remarked that avoiding a go-around even though 'a little bit' unstable saves fuel (and hence costs) - EZY is not the only company receiving a massive insurance premium reduction on the basis of the 500' policy, and associated proven flight safety benefits.
If it is recognised, as by some folks on here, that Flap 3 approaches are often a little more 'slippery', then surely the answer is a no-brainer: plan to begin configuring earlier (with advice to ATC if under proessure to keep high speed - I have never had any grief from ATC by giving them timely notice of extra track miles or speed reductions required, even in France!). Some of the posts on here crying 'airmanship' or going on about the divine right of the pilot to ignore a clear, safe, straightforward company policy smack more of ego than an attempt to operate in the safest possible manner.
I will keep my aircraft safe, but once that is achieved - it's not my train set, and I will operate how I am required to by my boss.
(btw, don't our training dept and management get some credit for their 'experience', in the same way that this individual is assumed innocent because of his?)
73 Yes I understand exactly what you (and others) aret talking about, however I think this isn't really the right place to be dicussing the in's and out's of descent and fuel burn techniques - hense I removed my post.
All the best.
All the best.
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As I said in post# 125 regarding descent fuel burn:
Isn't that the same thing?
Tech Log anyone?
Min fuel burn = max time at idle thrust in descent!
Tech Log anyone?
My guess is the company wanted to set an example and this captain happened to become the scapegoat.
Do you really think that in todays climate of employment law/BALPA representation that ANY company would be allowed to sack someone without just cause?
