Hello all,

Lately, I have heard some different applications of thrust reduction on NADP2 procedure. According to ICAO Doc. 8168, NADP2 procedure's thrust reduction is defined as:

Not before 240 m (800 ft) and while maintaining a
positive rate of climb, accelerate towards Vzf and reduce
power with the initiation of the first flap/slat retraction
or
when flaps/slats are retracted and while maintaining
a positive rate climb, reduce power and climb at
Vzf
Vzf + 20 to 40 km/h (Vzf + 10 to 20 kt)

On the other hand, some companies apply the procedure briefly as:
Reduce power right away at 800-1000ft and accelerate with reduced power.

I see some problems about this application besides it is not the written procedure. For example it will cause aircraft to lose climb rate during clean up. This can be a problem especially during a hot weather, high elevation, heavy aircraft operation or departing close to residential area etc.

I would like to hear your ideas and your company's NADP2 power reduction procedure. How do you do this? Especially Airbus pilots, how do you set THR Reduction and Accelaration altitudes on PERF page. Do you obey LVR CLB reminder and reduce power or do you wait until clean up even though LVR CLB flashes?

Regards!

Climb rate is indeed reduced but this is accounted for in the calculation. If the conditions mean the required climb rate won't be maintained with the mandated climb procedure we inform ATC and they can change runway, waive the procedure, and so on.

Typically, THR RED and ACC altitudes are set automatically when you enter the runway and departure. At most places I've flown, they're the same altitude (NADP2).

- THR RED altitude has to do with thrust modes, and triggers THR CLB flashing in the first (thrust) column of the FMA. Once the lever is moved, the thrust mode changes from FLX, TOGA, or DRT to THR CLB (or more commonly THRDCLBx).
- Acceleration altitude has to do with the vertical modes. The acceleration altitude triggers a change from SRS to CLB. The change in vertical mode is from SRS to CLB.

There are three basic cases:
- NADP2, thrust reduction and acceleration altitudes the same. Once LVR CLB flashes on the FMA, reduce thrust to CLB. This can be delayed as appropriate. Once above acceleration altitude, flaps/slats can be retracted on schedule. This order is as per the FCOM.
- NADP1, acceleration altitude is higher than thrust reduction. Reduce thrust at thrust reduction, then keep climbing until acceleration altitude. Once the aircraft accelerates, retract on schedule.
- Thrust reduction altitude is higher than acceleration altitude, once the aircraft accelerates, retract on schedule. At thrust reduction altitude, reduce to climb thrust.

Starlionblue wrote:

Climb rate is indeed reduced but this is accounted for in the calculation. If the conditions mean the required climb rate won't be maintained with the mandated climb procedure we inform ATC and they can change runway, waive the procedure, and so on.

Typically, THR RED and ACC altitudes are set automatically when you enter the runway and departure. At most places I've flown, they're the same altitude (NADP2).

- THR RED altitude has to do with thrust modes, and triggers THR CLB flashing in the first (thrust) column of the FMA. Once the lever is moved, the thrust mode changes from FLX, TOGA, or DRT to THR CLB (or more commonly THRDCLBx).
- Acceleration altitude has to do with the vertical modes. The acceleration altitude triggers a change from SRS to CLB. The change in vertical mode is from SRS to CLB.

There are three basic cases:
- NADP2, thrust reduction and acceleration altitudes the same. Once LVR CLB flashes on the FMA, reduce thrust to CLB. This can be delayed as appropriate. Once above acceleration altitude, flaps/slats can be retracted on schedule. This order is as per the FCOM.
- NADP1, acceleration altitude is higher than thrust reduction. Reduce thrust at thrust reduction, then keep climbing until acceleration altitude. Once the aircraft accelerates, retract on schedule.
- Thrust reduction altitude is higher than acceleration altitude, once the aircraft accelerates, retract on schedule. At thrust reduction altitude, reduce to climb thrust.

Thank you for this detailed explanation. It is very informative. By the way, I want to clearify, it is normal to lose climb rate during accelaration. I was comparing reducing thrust at initiation of accelaration with accelaration with takeoff thrust until slat/flap retraction or until clean up as it is written on ICAO rules.

And I will be happy to hear practical applications of NADP2. Not all companies or pilots strictly follow what book says, so actual applications will be appreciated to see here.

Thanks.

kemala wrote:

And I will be happy to hear practical applications of NADP2. Not all companies or pilots strictly follow what book says, so actual applications will be appreciated to see here.

Thanks.

Sorry, but I have to ask how you arrived at this statement? Having flown commercially for over 35 years, I have never seen nor heard of that. In addition, what airline would risk their AOC for not complying with a mandated departure procedure?

kemala wrote:

Starlionblue wrote:

Climb rate is indeed reduced but this is accounted for in the calculation. If the conditions mean the required climb rate won't be maintained with the mandated climb procedure we inform ATC and they can change runway, waive the procedure, and so on.

Typically, THR RED and ACC altitudes are set automatically when you enter the runway and departure. At most places I've flown, they're the same altitude (NADP2).

- THR RED altitude has to do with thrust modes, and triggers THR CLB flashing in the first (thrust) column of the FMA. Once the lever is moved, the thrust mode changes from FLX, TOGA, or DRT to THR CLB (or more commonly THRDCLBx).
- Acceleration altitude has to do with the vertical modes. The acceleration altitude triggers a change from SRS to CLB. The change in vertical mode is from SRS to CLB.

There are three basic cases:
- NADP2, thrust reduction and acceleration altitudes the same. Once LVR CLB flashes on the FMA, reduce thrust to CLB. This can be delayed as appropriate. Once above acceleration altitude, flaps/slats can be retracted on schedule. This order is as per the FCOM.
- NADP1, acceleration altitude is higher than thrust reduction. Reduce thrust at thrust reduction, then keep climbing until acceleration altitude. Once the aircraft accelerates, retract on schedule.
- Thrust reduction altitude is higher than acceleration altitude, once the aircraft accelerates, retract on schedule. At thrust reduction altitude, reduce to climb thrust.

Thank you for this detailed explanation. It is very informative. By the way, I want to clearify, it is normal to lose climb rate during accelaration. I was comparing reducing thrust at initiation of accelaration with accelaration with takeoff thrust until slat/flap retraction or until clean up as it is written on ICAO rules.

And I will be happy to hear practical applications of NADP2. Not all companies or pilots strictly follow what book says, so actual applications will be appreciated to see here.

Thanks.

In practical terms, there is gobs of thrust available with all engines running. Even when you're fairly heavy the aircraft will keep climbing like a homesick angel unless you reduce thrust. So yes, you'll lose a bit of climb rate, but there's still plenty. Less thrust is much more relaxing in the initial climb.

In windshear training in the sim, you keep climbing with TOGA until out of windshear. The recovery from that to normal operation can actually feel a bit hectic as you now have massive amounts of excess energy and need to stop climbing whilst also not accelerating too much.


As VMCA787 says, operators comply with whatever regulation is in place. If we intentionally violated regulations without a very good reason we'd find ourselves having tea and biscuits with the chief pilot. Without the biscuits. Or the Tea.

kemala, at the company at which I work, in the United States, NADP2 is the standard procedure. The only time we use NADP1 profile is when specifically instructed to do so by company directive.

The information below is applicable to the Airbus A-320 series.

During preflight, the PF inputs thrust reduction/acceleration altitude in the PERF page of the FMS--for NADP2: 1000 feet / 1000 feet (this is AFE--above field elevation). For NADP1 we use 1000/3000.

After takeoff, in SRS mode, the flight director commands a pitch attitude that will result in a climb speed of V2 + 10 (both engines operating) or V2 (single engine).
At 1000 feet AFE, the climb mode changes from SRS to CLB, LVR CLB is annunciated in column 2 of the FMA, and the flight director will command a decrease in pitch attitude to allow the aircraft to accelerate. At that point, we move the thrust levers from TOGA or FLEX/MCT to CL. If the takeoff was made using Flaps 2 or 3, we select Flaps 1 in sequence when the airspeed is at or above F speed, then retract the flaps once airspeed is at or above S speed. The airspeed continues to increase until reaching 250 KIAS (or as specified based on the SID or local procedures).

For NADP1, when the aircraft reaches 1000 feet AFE, the flight directors will command a decrease in pitch attitude so as to maintain V2 + 10 (based on reduction of thrust to CL) and we maintain V2 + 10, as well as the takeoff flap configuration, until reaching 3000 feet AFE. At that point, the flight director will command a pitch reduction to allow the aircraft to accelerate and we retract the flaps on schedule and continue to accelerate to climb airspeed.

It is very straightforward.

With regard to your question:

kemala wrote:

Do you obey LVR CLB reminder and reduce power or do you wait until clean up even though LVR CLB flashes?

We always reduce thrust to CL when LVR CLB annunciator flashes. If we delay the reduction in thrust, we would not be complying with the intent of the noise abatement departure procedure.

Also, you stated, "it will cause aircraft to lose climb rate during clean up. This can be a problem especially during a hot weather, high elevation, heavy aircraft operation or departing close to residential area etc."

I have departed under all of the above conditions, occasionally all of them simultaneously, and have never had a problem with aircraft performance. The NADP2 profile takes into account that climb rate will decrease during acceleration. That is normal.

Also, I didn't understand you statement about being a problem departing close to residential area. Is this not the purpose of a NADP--to reduce the noise footprint over residential areas?

I hope this information is helpful.

e38

kemala wrote:

And I will be happy to hear practical applications of NADP2. Not all companies or pilots strictly follow what book says, so actual applications will be appreciated to see here.
Thanks.

Some would say this is nitpicking but actually you're quite right :

kemala wrote:

Not before 240 m (800 ft) and while maintaining a positive rate of climb, accelerate towards Vzf and reduce power with the initiation of the first flap/slat retraction
or
when flaps/slats are retracted and while maintaining a positive rate climb, reduce power and climb at Vzf + 20 to 40 km/h (Vzf + 10 to 20 kt)

The acceleration to Vzf until 3000ft AFE is often overlooked, and people tend to mix the low acceleration height procedure which is pretty much standard nowadays, with the actual NADP2. The vast majority of us would accelerate straight to 250 kt after cleaning up, which is wrong.
In Europe, the reality is very few airports enforce actual NADP2. Most of the time they either have no NADP at all (low accel height is ok for them), or some kind of non standard NADP1 (France is famous for still enforcing the old NADP A), or simply have some speed/alt restrictions coded directly in the SID which ultimately make you fly a profile very close to a NADP2.

CeddP wrote:

kemala wrote:

And I will be happy to hear practical applications of NADP2. Not all companies or pilots strictly follow what book says, so actual applications will be appreciated to see here.
Thanks.

Some would say this is nitpicking but actually you're quite right :

kemala wrote:

Not before 240 m (800 ft) and while maintaining a positive rate of climb, accelerate towards Vzf and reduce power with the initiation of the first flap/slat retraction
or
when flaps/slats are retracted and while maintaining a positive rate climb, reduce power and climb at Vzf + 20 to 40 km/h (Vzf + 10 to 20 kt)

The acceleration to Vzf until 3000ft AFE is often overlooked, and people tend to mix the low acceleration height procedure which is pretty much standard nowadays, with the actual NADP2. The vast majority of us would accelerate straight to 250 kt after cleaning up, which is wrong.
In Europe, the reality is very few airports enforce actual NADP2. Most of the time they either have no NADP at all (low accel height is ok for them), or some kind of non standard NADP1 (France is famous for still enforcing the old NADP A), or simply have some speed/alt restrictions coded directly in the SID which ultimately make you fly a profile very close to a NADP2.

"Standard noise abatement" at my operator does include "Green Dot (Vzf) to 3000ft" after flap retraction, so we don't accelerate to 250kt. However in practice by the time you reach 3000ft, you might not even have had time to accelerate to Vzf. At 1500ft, thrust goes to CLB, and by the time you call for flaps zero and the PM moves the lever, you're probably well past 2000ft already.

Of course, if you start accelerating at 800ft, it's another story.

VMCA787 wrote:

Sorry, but I have to ask how you arrived at this statement? Having flown commercially for over 35 years, I have never seen nor heard of that. In addition, what airline would risk their AOC for not complying with a mandated departure procedure?

Then you were a lucky man, captain. I have reached that end by flying with many different captains from different countries and backgrounds. If it is not vital, people tends to have own SOP.

Starlionblue wrote:

"Standard noise abatement" at my operator does include "Green Dot (Vzf) to 3000ft" after flap retraction, so we don't accelerate to 250kt. However in practice by the time you reach 3000ft, you might not even have had time to accelerate to Vzf. At 1500ft, thrust goes to CLB, and by the time you call for flaps zero and the PM moves the lever, you're probably well past 2000ft already.

Of course, if you start accelerating at 800ft, it's another story.

Thank you for this valuable feedback. This is kind of an answer that I was expecting to hear. As I could understand, your company procedure obeys ICAO rule by maintaining greendot until 3000' but still thrust reduction sequence is not exactly what is written, is that right? You reduce thrust right after reaching thrust reduction altitude, before initiation of slats/flaps retraction...

e38 wrote:

kemala, at the company at which I work, in the United States, NADP2 is the standard procedure. The only time we use NADP1 profile is when specifically instructed to do so by company directive.

The information below is applicable to the Airbus A-320 series.

During preflight, the PF inputs thrust reduction/acceleration altitude in the PERF page of the FMS--for NADP2: 1000 feet / 1000 feet (this is AFE--above field elevation). For NADP1 we use 1000/3000.

After takeoff, in SRS mode, the flight director commands a pitch attitude that will result in a climb speed of V2 + 10 (both engines operating) or V2 (single engine).
At 1000 feet AFE, the climb mode changes from SRS to CLB, LVR CLB is annunciated in column 2 of the FMA, and the flight director will command a decrease in pitch attitude to allow the aircraft to accelerate. At that point, we move the thrust levers from TOGA or FLEX/MCT to CL. If the takeoff was made using Flaps 2 or 3, we select Flaps 1 in sequence when the airspeed is at or above F speed, then retract the flaps once airspeed is at or above S speed. The airspeed continues to increase until reaching 250 KIAS (or as specified based on the SID or local procedures).

With regard to your question:

kemala wrote:

Do you obey LVR CLB reminder and reduce power or do you wait until clean up even though LVR CLB flashes?

We always reduce thrust to CL when LVR CLB annunciator flashes. If we delay the reduction in thrust, we would not be complying with the intent of the noise abatement departure procedure.

Also, you stated, "it will cause aircraft to lose climb rate during clean up. This can be a problem especially during a hot weather, high elevation, heavy aircraft operation or departing close to residential area etc."

I have departed under all of the above conditions, occasionally all of them simultaneously, and have never had a problem with aircraft performance. The NADP2 profile takes into account that climb rate will decrease during acceleration. That is normal.

Also, I didn't understand you statement about being a problem departing close to residential area. Is this not the purpose of a NADP--to reduce the noise footprint over residential areas?

I hope this information is helpful.

e38

Thank you for this highly detailed and explained contribution as well. This was also something I was expecting to see as an answer. So, again, what I understand is you also reduce thrust right after reaching thrust reduction altitude, before reaching slats/flaps retraction speed. Which is also not exactly what is defined for NADP2 by ICAO.

And thank you for sharing experience about losing climb rate. I don't remember which engine was it, but when I was flying with A320, we were also applying procedure as you defined. I remember some flights where we reduced thrust right after LVR CLB flashes and aircraft was losing speed suddenly and was commanding an instant nose down, which causes a slight uncomfort for passenger. I remember one captain who recommended setting THR Reduction/Acceleration as 1200/1000. As you can imagine, aircraft was starting acceleration at 1000' and was ordering thrust reduction at 1200'. It was an uncommon execution but was very smooth accelaration and was very comfortable for pax. I hardly felt pitch attitude changes.

About residential area, you know, NADP1 is preferred when residentials are close to airport, and NADP2 is for a bit further ones. So, is we execute procedure as it is defined by ICAO, we would keep higher thrust a bit longer, thus a better climb rate until reaching cleanup.


By the way, maybe you ask yourself why it is so important as it won't have a big impact on climb gradient or noise. I just wanted to discuss the truth here and wanted to know how seriously it is taken by other companies. I also apply the procedure as company dictates as 1000/1000 and I reduce thrust whenever LVR CLB flashes and I observe pitch down order. But knowing to truth and knowing why not to follow it strictly makes a difference for me. As we do a global job, it is really good to hear others here.

Starlionblue wrote:

As VMCA787 says, operators comply with whatever regulation is in place. If we intentionally violated regulations without a very good reason we'd find ourselves having tea and biscuits with the chief pilot. Without the biscuits. Or the Tea.

Thank you. I hope we don't visit chief pilot for a tea and biscuits after some violations.

CeddP wrote:

The acceleration to Vzf until 3000ft AFE is often overlooked, and people tend to mix the low acceleration height procedure which is pretty much standard nowadays, with the actual NADP2. The vast majority of us would accelerate straight to 250 kt after cleaning up, which is wrong.
In Europe, the reality is very few airports enforce actual NADP2. Most of the time they either have no NADP at all (low accel height is ok for them), or some kind of non standard NADP1 (France is famous for still enforcing the old NADP A), or simply have some speed/alt restrictions coded directly in the SID which ultimately make you fly a profile very close to a NADP2.

Thank you CeddP, it was also good to hear your observations. So I think many companies and especially Airbus pilots do follow LVR CLB order to reduce thrust and they accelerate towards 250kts as it comes automatically by FMGC.

kemala wrote:

Starlionblue wrote:

"Standard noise abatement" at my operator does include "Green Dot (Vzf) to 3000ft" after flap retraction, so we don't accelerate to 250kt. However in practice by the time you reach 3000ft, you might not even have had time to accelerate to Vzf. At 1500ft, thrust goes to CLB, and by the time you call for flaps zero and the PM moves the lever, you're probably well past 2000ft already.

Of course, if you start accelerating at 800ft, it's another story.

Thank you for this valuable feedback. This is kind of an answer that I was expecting to hear. As I could understand, your company procedure obeys ICAO rule by maintaining greendot until 3000' but still thrust reduction sequence is not exactly what is written, is that right? You reduce thrust right after reaching thrust reduction altitude, before initiation of slats/flaps retraction...

Going back to ICAO document 8168, which you can read here: http://www.chcheli.com/sites/default/fi ... _vol_1.pdf

NADP 2 is on page 145. Here's the relevant bit.

3.4 On reaching an altitude equivalent to at least 240 m (800 ft) above aerodrome elevation, decrease aircraft body angle/angle of pitch while maintaining a positive rate of climb, accelerate towards VZF and either:

a) reduce power with the initiation of the first flap/slat retraction; or

b) reduce power after flap/slat retraction

Point a) says "with". To me, this would mean there is no ironclad requirement to start retracting flaps before reducing power. The actions are done as a sequence, thus complying with the formulation "with".

LVR CLB flashing.
Thrust levers go to CLB
"Thrust Dee-climb 2, climb, auto-thrust."
"Checked."
Aircraft accelerates.
"Flaps zero."
"Speed checked. Flaps zero."
"After take-off checklist."


Company operations manuals must be approved by the relevant regulator, and operations are regularly observed by said regulator. They wouldn't let us keep doing the wrong thing. For that matter, Airbus wouldn't specify an incorrect procedure in the FCOM.

kemala wrote:

I remember some flights where we reduced thrust right after LVR CLB flashes and aircraft was losing speed suddenly and was commanding an instant nose down, which causes a slight uncomfort for passenger. I remember one captain who recommended setting THR Reduction/Acceleration as 1200/1000.

kemala, when you stated "aircraft was losing speed suddenly and was commanding an instant nose down, which causes a slight uncomfortable for passengers," in my experience, Airbus A-320 series, when the aircraft reaches 1000 feet AFE and the annunciator flashes LVR CLB, as we reduce thrust from TOGA or FLEX/MCT to CLB and lower the nose smoothly 1 or 2 degrees, the airspeed remains fairly constant and then begins to accelerate. By executing the procedure gently and smoothly, I have not experienced a sudden reduction in airspeed; nor has it been uncomfortable for the passengers of which I am aware.

Also, if a pilot set THR Reduction/Acceleration 1200/1000, it would be a violation of company procedures. We are only authorized to set 1000/1000 or 1000/3000, as specified in company procedure for the applicable airport/runway.

And you are correct, NADP1 = Close-in community noise abatement departure procedure; NADP2 = Distant community noise abatement departure procedure.

e38

e38 wrote:

kemala wrote:

I remember some flights where we reduced thrust right after LVR CLB flashes and aircraft was losing speed suddenly and was commanding an instant nose down, which causes a slight uncomfort for passenger. I remember one captain who recommended setting THR Reduction/Acceleration as 1200/1000.

kemala, when you stated "aircraft was losing speed suddenly and was commanding an instant nose down, which causes a slight uncomfortable for passengers," in my experience, Airbus A-320 series, when the aircraft reaches 1000 feet AFE and the annunciator flashes LVR CLB, as we reduce thrust from TOGA or FLEX/MCT to CLB and lower the nose smoothly 1 or 2 degrees, the airspeed remains fairly constant and then begins to accelerate. By executing the procedure gently and smoothly, I have not experienced a sudden reduction in airspeed; nor has it been uncomfortable for the passengers of which I am aware.

Also, if a pilot set THR Reduction/Acceleration 1200/1000, it would be a violation of company procedures. We are only authorized to set 1000/1000 or 1000/3000, as specified in company procedure for the applicable airport/runway.

And you are correct, NADP1 = Close-in community noise abatement departure procedure; NADP2 = Distant community noise abatement departure procedure.

e38

"The aircraft is losing speed and an immediate nose down is commanded" sounds like improper handling to me.

The flight director should not be used for dynamic manoeuvres. At acceleration altitude, the pitch bar will instantly jump down. You're not meant to pitch down fast to follow. Anticipate by smoothly pitching down to the approximate pitch you expect. Once the pitch bar has jumped down and settled, smoothly adjust to follow the flight director. This required adjustment will typically be minor.

If in autoflight, the autopilot certainly flies very smoothly, without losing speed or an immediate nose down.

As you say, if you do it properly, it won't be uncomfortable.

kemala wrote:

VMCA787 wrote:

Sorry, but I have to ask how you arrived at this statement? Having flown commercially for over 35 years, I have never seen nor heard of that. In addition, what airline would risk their AOC for not complying with a mandated departure procedure?

Then you were a lucky man, captain. I have reached that end by flying with many different captains from different countries and backgrounds. If it is not vital, people tends to have own SOP.

All, I can say is that from the beginning of my aviation career, it was drilled into my mind to follow the procedures. I have been a F/O, Captain, TRI, TRE and Chief Pilot in my career. I have always preached that the procedures are there for a reason. That reason is pilots aren't smart enough to come up with a better procedure. I know I'm not!! If something happens, the first place they will look is at the crew's actions. If the actions are not in accordance with the approved SOP, then the crew is finished. I don't care what the cause was, the crew will be hung out to dry. End of story. I know there are pilots who fly one way on the line and another way in the sim, but I am not smart or clever enough. In fact, they aren't either. At some point in time, it will come back and haunt them. And, that will be the end of that pilot's career or at least their employment at that airline.

I have done contract work for Airbus and Boeing and I know there are cultural biases in many airlines. For example, the Captain's authority. In some airlines, the Captain is considered a god and no one questions his or her actions. Accident investigations have proven that doesn't work. So, it sounds like the is the culture where you work. My condolences!!

@VMCA787 well said. About me, I have seen harsh times but now quite good. Gods have been retired thankfully. Thank you!
@Starlionblue and @e38 thank you too. Great contributions.

I will agree the 3000AGL is much overlooked in the US, most companies tend to go right to 250. A certain US legacy airline requires flaps up clean speed on all aircraft (except the 747 when that was in the fleet) until 3000 AGL. On the Airbus they simply program clean speed into the CLB page then push managed speed at 3000AGL. In the 757/767 they put the clean speed / 3000 in the climb page as a speed restriction.