A320/A321 energy management and configuration
Joined: Jul 2000
Posts: 1,061
Likes: 20
From: My views - Not my employer!
321XLR - I think the differing answers come because folk are based in different continents. Most US airfields have so many altitude constraints on arrivals/departures that DES/CLB would indeed be the primary way to go (especially the descend via ATC instruction which fits this mode well). Europe has comparatively few constraints and actually some ATC units actually require a fixed descent rate (specified at the time and not charted). Ref climb/descent rates using Open Climb/Des - Our operator asks us to limit V/S approaching a cleared altitude when around other aircraft, so if in DES we would be reverting to V/S anyhow.. So yes, your answer is good for the US, but actually there are many ways of achieving the goal...
Joined: Dec 2020
Posts: 71
Likes: 110
From: Scandinavia-home of the midnight sun.
Well, as a long time Boeing driver previously, I was quite astonished wrt the incredibly inefficient descent profile on the A320. In my airline we are very fuel conscious and flt ops go to great lengths as to push for efficient, green ops when / where possible.
We have a mix of ceo and neo. Our neo´s are all equipped with DPO (descent profile optimisation), which make the managed descent profile a little less poor.
In my book, any professional airline pilot should strive for an IDLE descent from TOD until just about at the approach stabilisation gate (1000ft AAE).
I know that this is not always possible as ATC /airspace restrictions etc play a part, but when able that is what we do. It is smooth, saves both money and the environment, and is part of the fun of always trying to make the "perfect" flight.
So, we have something on the non-DPO ceo we call the "10% rule" : This means we go beyond the TOD and start descend in OP DES to stay 10% abv the airbus profile. Ex, you cruise at FL350 and dest is at sea level. This means you pull for OP DES app. when you are 2700 ft high (it takes quite long for the bus to go from level flt to get the nose pointing down..). This will put you app 3500 ft (10%) abv the profile initially.
Since you are at an efficient idle, your descent profile will slowly close towards the airbus profile, and you continuously x-check as you descend (passing fl 300 you will be app 3000 "high", at fl 200 2000ft "high" etc, you get the point.
This works great, again, on a non DPO aircraft.
As for the neo, with DPO, I simply go past the TOD with app. 300-400ft then pull for OP DES.
If winds are a bit off etc, you simply have to pull for selected speed and adjust to play with the energy of the aircraft to stay on the idle profile.
Someone might now think, what about constraints? How do you ascertain not busting any alt constraints on the way down if you are not in DES mode??
Simples, again using the "10%" rule: cruise FL350, cross XXX VOR at or below FL150, diff between FL350 and FL 150 is 20000 ft. You simply start down with being 2000ft "high" and monitor on the way down. If that is a problem for any half decent pilot, then our industry is in worse shape than I thought.
Again, as professional aviators, we should take pride in operating as safe, and as EFFICIENT as possible, and a generic diff between OP DES vs DES is app 30% more fuel burn in DES. That is in my opinion, sloppy.
However, if I am performing an RNP AR approach with multiple close-to -each-other alt constraints during the approach, then I set the temp corrected Final Descent Point altitude on the FCU, and press DES, as it will reduce workload quite a bit as the DES will pass each constraint correctly without me having to sit and change FCU alt numerous times on the approach. //TRI/TRE at a European legacy.
I
We have a mix of ceo and neo. Our neo´s are all equipped with DPO (descent profile optimisation), which make the managed descent profile a little less poor.
In my book, any professional airline pilot should strive for an IDLE descent from TOD until just about at the approach stabilisation gate (1000ft AAE).
I know that this is not always possible as ATC /airspace restrictions etc play a part, but when able that is what we do. It is smooth, saves both money and the environment, and is part of the fun of always trying to make the "perfect" flight.
So, we have something on the non-DPO ceo we call the "10% rule" : This means we go beyond the TOD and start descend in OP DES to stay 10% abv the airbus profile. Ex, you cruise at FL350 and dest is at sea level. This means you pull for OP DES app. when you are 2700 ft high (it takes quite long for the bus to go from level flt to get the nose pointing down..). This will put you app 3500 ft (10%) abv the profile initially.
Since you are at an efficient idle, your descent profile will slowly close towards the airbus profile, and you continuously x-check as you descend (passing fl 300 you will be app 3000 "high", at fl 200 2000ft "high" etc, you get the point.
This works great, again, on a non DPO aircraft.
As for the neo, with DPO, I simply go past the TOD with app. 300-400ft then pull for OP DES.
If winds are a bit off etc, you simply have to pull for selected speed and adjust to play with the energy of the aircraft to stay on the idle profile.
Someone might now think, what about constraints? How do you ascertain not busting any alt constraints on the way down if you are not in DES mode??
Simples, again using the "10%" rule: cruise FL350, cross XXX VOR at or below FL150, diff between FL350 and FL 150 is 20000 ft. You simply start down with being 2000ft "high" and monitor on the way down. If that is a problem for any half decent pilot, then our industry is in worse shape than I thought.
Again, as professional aviators, we should take pride in operating as safe, and as EFFICIENT as possible, and a generic diff between OP DES vs DES is app 30% more fuel burn in DES. That is in my opinion, sloppy.
However, if I am performing an RNP AR approach with multiple close-to -each-other alt constraints during the approach, then I set the temp corrected Final Descent Point altitude on the FCU, and press DES, as it will reduce workload quite a bit as the DES will pass each constraint correctly without me having to sit and change FCU alt numerous times on the approach. //TRI/TRE at a European legacy.
I
Joined: Mar 2011
Posts: 105
Likes: 0
From: Italy
Well, as a long time Boeing driver previously, I was quite astonished wrt the incredibly inefficient descent profile on the A320. In my airline we are very fuel conscious and flt ops go to great lengths as to push for efficient, green ops when / where possible.
We have a mix of ceo and neo. Our neo´s are all equipped with DPO (descent profile optimisation), which make the managed descent profile a little less poor.
In my book, any professional airline pilot should strive for an IDLE descent from TOD until just about at the approach stabilisation gate (1000ft AAE).
I know that this is not always possible as ATC /airspace restrictions etc play a part, but when able that is what we do. It is smooth, saves both money and the environment, and is part of the fun of always trying to make the "perfect" flight.
So, we have something on the non-DPO ceo we call the "10% rule" : This means we go beyond the TOD and start descend in OP DES to stay 10% abv the airbus profile. Ex, you cruise at FL350 and dest is at sea level. This means you pull for OP DES app. when you are 2700 ft high (it takes quite long for the bus to go from level flt to get the nose pointing down..). This will put you app 3500 ft (10%) abv the profile initially.
Since you are at an efficient idle, your descent profile will slowly close towards the airbus profile, and you continuously x-check as you descend (passing fl 300 you will be app 3000 "high", at fl 200 2000ft "high" etc, you get the point.
This works great, again, on a non DPO aircraft.
As for the neo, with DPO, I simply go past the TOD with app. 300-400ft then pull for OP DES.
If winds are a bit off etc, you simply have to pull for selected speed and adjust to play with the energy of the aircraft to stay on the idle profile.
Someone might now think, what about constraints? How do you ascertain not busting any alt constraints on the way down if you are not in DES mode??
Simples, again using the "10%" rule: cruise FL350, cross XXX VOR at or below FL150, diff between FL350 and FL 150 is 20000 ft. You simply start down with being 2000ft "high" and monitor on the way down. If that is a problem for any half decent pilot, then our industry is in worse shape than I thought.
Again, as professional aviators, we should take pride in operating as safe, and as EFFICIENT as possible, and a generic diff between OP DES vs DES is app 30% more fuel burn in DES. That is in my opinion, sloppy.
However, if I am performing an RNP AR approach with multiple close-to -each-other alt constraints during the approach, then I set the temp corrected Final Descent Point altitude on the FCU, and press DES, as it will reduce workload quite a bit as the DES will pass each constraint correctly without me having to sit and change FCU alt numerous times on the approach. //TRI/TRE at a European legacy.
I
We have a mix of ceo and neo. Our neo´s are all equipped with DPO (descent profile optimisation), which make the managed descent profile a little less poor.
In my book, any professional airline pilot should strive for an IDLE descent from TOD until just about at the approach stabilisation gate (1000ft AAE).
I know that this is not always possible as ATC /airspace restrictions etc play a part, but when able that is what we do. It is smooth, saves both money and the environment, and is part of the fun of always trying to make the "perfect" flight.
So, we have something on the non-DPO ceo we call the "10% rule" : This means we go beyond the TOD and start descend in OP DES to stay 10% abv the airbus profile. Ex, you cruise at FL350 and dest is at sea level. This means you pull for OP DES app. when you are 2700 ft high (it takes quite long for the bus to go from level flt to get the nose pointing down..). This will put you app 3500 ft (10%) abv the profile initially.
Since you are at an efficient idle, your descent profile will slowly close towards the airbus profile, and you continuously x-check as you descend (passing fl 300 you will be app 3000 "high", at fl 200 2000ft "high" etc, you get the point.
This works great, again, on a non DPO aircraft.
As for the neo, with DPO, I simply go past the TOD with app. 300-400ft then pull for OP DES.
If winds are a bit off etc, you simply have to pull for selected speed and adjust to play with the energy of the aircraft to stay on the idle profile.
Someone might now think, what about constraints? How do you ascertain not busting any alt constraints on the way down if you are not in DES mode??
Simples, again using the "10%" rule: cruise FL350, cross XXX VOR at or below FL150, diff between FL350 and FL 150 is 20000 ft. You simply start down with being 2000ft "high" and monitor on the way down. If that is a problem for any half decent pilot, then our industry is in worse shape than I thought.
Again, as professional aviators, we should take pride in operating as safe, and as EFFICIENT as possible, and a generic diff between OP DES vs DES is app 30% more fuel burn in DES. That is in my opinion, sloppy.
However, if I am performing an RNP AR approach with multiple close-to -each-other alt constraints during the approach, then I set the temp corrected Final Descent Point altitude on the FCU, and press DES, as it will reduce workload quite a bit as the DES will pass each constraint correctly without me having to sit and change FCU alt numerous times on the approach. //TRI/TRE at a European legacy.
I
Many times I get very annoyed with managed des descending with some thrust while being very very low.
quick question: many approaches in Europe have some “snake arrivals” that 99% are cut with a significant shortcut. Most pilots stay a bit low to be ready to accept the shortcut. Do you have any technique like this 10% rule or something else?
Joined: Jan 2022
Posts: 106
Likes: 5
From: Miami
Well, as a long time Boeing driver previously, I was quite astonished wrt the incredibly inefficient descent profile on the A320. In my airline we are very fuel conscious and flt ops go to great lengths as to push for efficient, green ops when / where possible.
We have a mix of ceo and neo. Our neo´s are all equipped with DPO (descent profile optimisation), which make the managed descent profile a little less poor.
In my book, any professional airline pilot should strive for an IDLE descent from TOD until just about at the approach stabilisation gate (1000ft AAE).
I know that this is not always possible as ATC /airspace restrictions etc play a part, but when able that is what we do. It is smooth, saves both money and the environment, and is part of the fun of always trying to make the "perfect" flight.
So, we have something on the non-DPO ceo we call the "10% rule" : This means we go beyond the TOD and start descend in OP DES to stay 10% abv the airbus profile. Ex, you cruise at FL350 and dest is at sea level. This means you pull for OP DES app. when you are 2700 ft high (it takes quite long for the bus to go from level flt to get the nose pointing down..). This will put you app 3500 ft (10%) abv the profile initially.
Since you are at an efficient idle, your descent profile will slowly close towards the airbus profile, and you continuously x-check as you descend (passing fl 300 you will be app 3000 "high", at fl 200 2000ft "high" etc, you get the point.
This works great, again, on a non DPO aircraft.
As for the neo, with DPO, I simply go past the TOD with app. 300-400ft then pull for OP DES.
If winds are a bit off etc, you simply have to pull for selected speed and adjust to play with the energy of the aircraft to stay on the idle profile.
Someone might now think, what about constraints? How do you ascertain not busting any alt constraints on the way down if you are not in DES mode??
Simples, again using the "10%" rule: cruise FL350, cross XXX VOR at or below FL150, diff between FL350 and FL 150 is 20000 ft. You simply start down with being 2000ft "high" and monitor on the way down. If that is a problem for any half decent pilot, then our industry is in worse shape than I thought.
Again, as professional aviators, we should take pride in operating as safe, and as EFFICIENT as possible, and a generic diff between OP DES vs DES is app 30% more fuel burn in DES. That is in my opinion, sloppy.
However, if I am performing an RNP AR approach with multiple close-to -each-other alt constraints during the approach, then I set the temp corrected Final Descent Point altitude on the FCU, and press DES, as it will reduce workload quite a bit as the DES will pass each constraint correctly without me having to sit and change FCU alt numerous times on the approach. //TRI/TRE at a European legacy.
I
We have a mix of ceo and neo. Our neo´s are all equipped with DPO (descent profile optimisation), which make the managed descent profile a little less poor.
In my book, any professional airline pilot should strive for an IDLE descent from TOD until just about at the approach stabilisation gate (1000ft AAE).
I know that this is not always possible as ATC /airspace restrictions etc play a part, but when able that is what we do. It is smooth, saves both money and the environment, and is part of the fun of always trying to make the "perfect" flight.
So, we have something on the non-DPO ceo we call the "10% rule" : This means we go beyond the TOD and start descend in OP DES to stay 10% abv the airbus profile. Ex, you cruise at FL350 and dest is at sea level. This means you pull for OP DES app. when you are 2700 ft high (it takes quite long for the bus to go from level flt to get the nose pointing down..). This will put you app 3500 ft (10%) abv the profile initially.
Since you are at an efficient idle, your descent profile will slowly close towards the airbus profile, and you continuously x-check as you descend (passing fl 300 you will be app 3000 "high", at fl 200 2000ft "high" etc, you get the point.
This works great, again, on a non DPO aircraft.
As for the neo, with DPO, I simply go past the TOD with app. 300-400ft then pull for OP DES.
If winds are a bit off etc, you simply have to pull for selected speed and adjust to play with the energy of the aircraft to stay on the idle profile.
Someone might now think, what about constraints? How do you ascertain not busting any alt constraints on the way down if you are not in DES mode??
Simples, again using the "10%" rule: cruise FL350, cross XXX VOR at or below FL150, diff between FL350 and FL 150 is 20000 ft. You simply start down with being 2000ft "high" and monitor on the way down. If that is a problem for any half decent pilot, then our industry is in worse shape than I thought.
Again, as professional aviators, we should take pride in operating as safe, and as EFFICIENT as possible, and a generic diff between OP DES vs DES is app 30% more fuel burn in DES. That is in my opinion, sloppy.
However, if I am performing an RNP AR approach with multiple close-to -each-other alt constraints during the approach, then I set the temp corrected Final Descent Point altitude on the FCU, and press DES, as it will reduce workload quite a bit as the DES will pass each constraint correctly without me having to sit and change FCU alt numerous times on the approach. //TRI/TRE at a European legacy.
I
Thank you
Joined: Jul 2018
Posts: 202
Likes: 69
From: on the edge.
Well, as a long time Boeing driver previously, I was quite astonished wrt the incredibly inefficient descent profile on the A320. In my airline we are very fuel conscious and flt ops go to great lengths as to push for efficient, green ops when / where possible.
We have a mix of ceo and neo. Our neo´s are all equipped with DPO (descent profile optimisation), which make the managed descent profile a little less poor.
In my book, any professional airline pilot should strive for an IDLE descent from TOD until just about at the approach stabilisation gate (1000ft AAE).
I know that this is not always possible as ATC /airspace restrictions etc play a part, but when able that is what we do. It is smooth, saves both money and the environment, and is part of the fun of always trying to make the "perfect" flight.
So, we have something on the non-DPO ceo we call the "10% rule" : This means we go beyond the TOD and start descend in OP DES to stay 10% abv the airbus profile. Ex, you cruise at FL350 and dest is at sea level. This means you pull for OP DES app. when you are 2700 ft high (it takes quite long for the bus to go from level flt to get the nose pointing down..). This will put you app 3500 ft (10%) abv the profile initially.
Since you are at an efficient idle, your descent profile will slowly close towards the airbus profile, and you continuously x-check as you descend (passing fl 300 you will be app 3000 "high", at fl 200 2000ft "high" etc, you get the point.
This works great, again, on a non DPO aircraft.
As for the neo, with DPO, I simply go past the TOD with app. 300-400ft then pull for OP DES.
If winds are a bit off etc, you simply have to pull for selected speed and adjust to play with the energy of the aircraft to stay on the idle profile.
Someone might now think, what about constraints? How do you ascertain not busting any alt constraints on the way down if you are not in DES mode??
Simples, again using the "10%" rule: cruise FL350, cross XXX VOR at or below FL150, diff between FL350 and FL 150 is 20000 ft. You simply start down with being 2000ft "high" and monitor on the way down. If that is a problem for any half decent pilot, then our industry is in worse shape than I thought.
Again, as professional aviators, we should take pride in operating as safe, and as EFFICIENT as possible, and a generic diff between OP DES vs DES is app 30% more fuel burn in DES. That is in my opinion, sloppy.
However, if I am performing an RNP AR approach with multiple close-to -each-other alt constraints during the approach, then I set the temp corrected Final Descent Point altitude on the FCU, and press DES, as it will reduce workload quite a bit as the DES will pass each constraint correctly without me having to sit and change FCU alt numerous times on the approach. //TRI/TRE at a European legacy.
I
We have a mix of ceo and neo. Our neo´s are all equipped with DPO (descent profile optimisation), which make the managed descent profile a little less poor.
In my book, any professional airline pilot should strive for an IDLE descent from TOD until just about at the approach stabilisation gate (1000ft AAE).
I know that this is not always possible as ATC /airspace restrictions etc play a part, but when able that is what we do. It is smooth, saves both money and the environment, and is part of the fun of always trying to make the "perfect" flight.
So, we have something on the non-DPO ceo we call the "10% rule" : This means we go beyond the TOD and start descend in OP DES to stay 10% abv the airbus profile. Ex, you cruise at FL350 and dest is at sea level. This means you pull for OP DES app. when you are 2700 ft high (it takes quite long for the bus to go from level flt to get the nose pointing down..). This will put you app 3500 ft (10%) abv the profile initially.
Since you are at an efficient idle, your descent profile will slowly close towards the airbus profile, and you continuously x-check as you descend (passing fl 300 you will be app 3000 "high", at fl 200 2000ft "high" etc, you get the point.
This works great, again, on a non DPO aircraft.
As for the neo, with DPO, I simply go past the TOD with app. 300-400ft then pull for OP DES.
If winds are a bit off etc, you simply have to pull for selected speed and adjust to play with the energy of the aircraft to stay on the idle profile.
Someone might now think, what about constraints? How do you ascertain not busting any alt constraints on the way down if you are not in DES mode??
Simples, again using the "10%" rule: cruise FL350, cross XXX VOR at or below FL150, diff between FL350 and FL 150 is 20000 ft. You simply start down with being 2000ft "high" and monitor on the way down. If that is a problem for any half decent pilot, then our industry is in worse shape than I thought.
Again, as professional aviators, we should take pride in operating as safe, and as EFFICIENT as possible, and a generic diff between OP DES vs DES is app 30% more fuel burn in DES. That is in my opinion, sloppy.
However, if I am performing an RNP AR approach with multiple close-to -each-other alt constraints during the approach, then I set the temp corrected Final Descent Point altitude on the FCU, and press DES, as it will reduce workload quite a bit as the DES will pass each constraint correctly without me having to sit and change FCU alt numerous times on the approach. //TRI/TRE at a European legacy.
I
Joined: Nov 1999
Aviation Qualifications: ATPL
Posts: 3,150
Likes: 744
From: UK
Can anyone give the difference in fuel used between a typical descent from cruise to landing, in managed DES and open DES for, say A320 ?
As actually measured not theoretically.
As actually measured not theoretically.
Thread Starter
Joined: Nov 2017
Posts: 26
Likes: 1
From: Milan
Hello,
Thanks to all advices, especially sonicbum one my descent has significantly improved. Our aircrafts (mostly) don’t have DPO thus using height*3 + 1nm each 10knts down to 200 really optimizes descent.
In your opinion in busy airspace where I expect ATC will ask me to decelerate many times while descending (ie speed 220 then speed 210 then 180) do I need to stay lower and account extra margins or not? As for many subjects many captains give different feedbacks (and prompts): some of them say that even if I will get speed deceleration by ATC while descending 5nm from 250 to decelerate is perfect, others that 5nm is fine only if I can keep 250 until close to level off, decel and configure. If I expect deceleration while descending should be lower and account maybe 10nm from 250 to decel…
Thanks to all advices, especially sonicbum one my descent has significantly improved. Our aircrafts (mostly) don’t have DPO thus using height*3 + 1nm each 10knts down to 200 really optimizes descent.
In your opinion in busy airspace where I expect ATC will ask me to decelerate many times while descending (ie speed 220 then speed 210 then 180) do I need to stay lower and account extra margins or not? As for many subjects many captains give different feedbacks (and prompts): some of them say that even if I will get speed deceleration by ATC while descending 5nm from 250 to decelerate is perfect, others that 5nm is fine only if I can keep 250 until close to level off, decel and configure. If I expect deceleration while descending should be lower and account maybe 10nm from 250 to decel…
Joined: Feb 2025
Posts: 8
Likes: 1
From: France
Hi,
First off all congratulations for having successfully completed your line training! A little less congratulations for your trainers that have left you with those unanswered questions
Let's look at a basic but effective descent management tool.
The good old Altitude x 3 to start with.
Then adjust the wind -> +/- 10% tail/head winds
Then adjust the speed + 1 NM for every 10 kt above 200 kt which is usually somewhere around Gdot.
Finally the weight adjustment. On the narrow body Airbus I don't bother too much; if I am very light I will probably need to reduce the RoD at some stage and if I am close to Max Landing Weight I might need to use some speed brakes.
So You need to start your descent from FL350 down to your platform of, let's say, 3000 ft.
32 x 3 = 96 NM
20 kt tailwind = +2 NM
Deceleration = 7 NM (descending at 270 kt)
Start descent in OP DES around 105 NM.
From there keep calculating and adjust, every 5000 feet or so. If you do have STAR constraints to meet in the middle you will need to set targets for the different constraints.
Generally speaking this sort of technique of descending in OP DES/VS works well to optimize fuel consumption when there are not too many constraints to be considered.
It is a "homemade" version of the Descent Profile Optimization by Airbus and can lead to some savings if applied correctly.
First off all congratulations for having successfully completed your line training! A little less congratulations for your trainers that have left you with those unanswered questions
Let's look at a basic but effective descent management tool.
The good old Altitude x 3 to start with.
Then adjust the wind -> +/- 10% tail/head winds
Then adjust the speed + 1 NM for every 10 kt above 200 kt which is usually somewhere around Gdot.
Finally the weight adjustment. On the narrow body Airbus I don't bother too much; if I am very light I will probably need to reduce the RoD at some stage and if I am close to Max Landing Weight I might need to use some speed brakes.
So You need to start your descent from FL350 down to your platform of, let's say, 3000 ft.
32 x 3 = 96 NM
20 kt tailwind = +2 NM
Deceleration = 7 NM (descending at 270 kt)
Start descent in OP DES around 105 NM.
From there keep calculating and adjust, every 5000 feet or so. If you do have STAR constraints to meet in the middle you will need to set targets for the different constraints.
Generally speaking this sort of technique of descending in OP DES/VS works well to optimize fuel consumption when there are not too many constraints to be considered.
It is a "homemade" version of the Descent Profile Optimization by Airbus and can lead to some savings if applied correctly.
