Execution of NADP
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Execution of NADP
Hi everyone!
In our company we use a standard thrust reduction altitude of 800ft which coincides with a standard acceleration altitude of 800ft also. Under normal departures with a T/O thrust rating including both fixed and assumed derate, the B737 also selects a CLB derate based on T/O thrust. Where a continuous climb can be expected to above FL150 it is recommended to select full CLB thrust for normal departures as it saves fuel.
However during departures with NADP1 or NADP2 we are not allowed to select full climb thrust until NADP is complete at 3000 AGL. At first glance this may seem logical, but I question this procedure. Why not program full CLB thrust during NADP ?
The answer many have given me is (logically) that you want to emit as low noise level as possible. This makes sense and is also according to an ICAO AMC. However the wording in the NADP specifications along with specific departures at certain dense traffic airports leads me to believe we got this all wrong.
Here's my argument:
Sound waves (or light for that matter) are primarily dependent on two main factors. The level of sound and the distance to the observer. If you double the sound level the observer will also observe a doubling of the sound. If you double the distance, the observer will observe a quarter of the sound emitted. It follows an inverse Pythagorean theorem.
With that knowledge it would be fair to assume that the idea behind NADP is to make departing aircrafts fly in such a manner that they would be as far from the noise sensitive area as possible. This can best be achieved by using as high thrust setting as possible so as to maximize the distance to noise sensitive areas. (I assume of course that the noise level between full CLB and CLB1 or CLB2 is very little in comparison)
If you look at the wording in NADP1 as stated by ICAO these procedures basically states that you are not allowed to select CLB thrust earlier than 800 ft, and that you should climb at V2 + 10-20kts until acceleration altitude of minimum 3000 ft AGL. As opposed to normal departure procedures where you can select CLB thurst at 400 ft AGL and clean up threreafter. Again the idea of getting up and away before you need to accelerate to clean up.
Jeppesen route manual also states in conjunction with NADP that aircrafts with FMC calculated thrust are not allowed to use a thrust setting less than that calculated by the FMC during NADP. Again "Keep thrust up" to get up and away from the noise sensitive areas.
Looking at the NADP for LGAV (Athens) states that unless for safety reasons you are not allowed to reduce T/O thrust until a minimum altitude of 1500 AGL (These are based on the older ICAO NADP A/B). Again "up and away" to minimize noise
NADP at LFPG (Charles de Gaulle): Maintain T/O thrust to 1500AGL then MAXIMUM CLB thrust to 3000AGL before accelerating. Here specifically they specify that you are not allowed to use reduced CLB thrust. Again compliant with "Up and Away" principle.
As it is already a stated fact that there is economy in selecting full CLB thrust when a continuous climb to above FL150 can be expected, I would like others opinion on making it a standard procedure to also select full CLB thrust wherever you have a NADP AND a continuous climb to above FL150 can be expected.
Any relevant inputs are highly appreciated!
In our company we use a standard thrust reduction altitude of 800ft which coincides with a standard acceleration altitude of 800ft also. Under normal departures with a T/O thrust rating including both fixed and assumed derate, the B737 also selects a CLB derate based on T/O thrust. Where a continuous climb can be expected to above FL150 it is recommended to select full CLB thrust for normal departures as it saves fuel.
However during departures with NADP1 or NADP2 we are not allowed to select full climb thrust until NADP is complete at 3000 AGL. At first glance this may seem logical, but I question this procedure. Why not program full CLB thrust during NADP ?
The answer many have given me is (logically) that you want to emit as low noise level as possible. This makes sense and is also according to an ICAO AMC. However the wording in the NADP specifications along with specific departures at certain dense traffic airports leads me to believe we got this all wrong.
Here's my argument:
Sound waves (or light for that matter) are primarily dependent on two main factors. The level of sound and the distance to the observer. If you double the sound level the observer will also observe a doubling of the sound. If you double the distance, the observer will observe a quarter of the sound emitted. It follows an inverse Pythagorean theorem.
With that knowledge it would be fair to assume that the idea behind NADP is to make departing aircrafts fly in such a manner that they would be as far from the noise sensitive area as possible. This can best be achieved by using as high thrust setting as possible so as to maximize the distance to noise sensitive areas. (I assume of course that the noise level between full CLB and CLB1 or CLB2 is very little in comparison)
If you look at the wording in NADP1 as stated by ICAO these procedures basically states that you are not allowed to select CLB thrust earlier than 800 ft, and that you should climb at V2 + 10-20kts until acceleration altitude of minimum 3000 ft AGL. As opposed to normal departure procedures where you can select CLB thurst at 400 ft AGL and clean up threreafter. Again the idea of getting up and away before you need to accelerate to clean up.
Jeppesen route manual also states in conjunction with NADP that aircrafts with FMC calculated thrust are not allowed to use a thrust setting less than that calculated by the FMC during NADP. Again "Keep thrust up" to get up and away from the noise sensitive areas.
Looking at the NADP for LGAV (Athens) states that unless for safety reasons you are not allowed to reduce T/O thrust until a minimum altitude of 1500 AGL (These are based on the older ICAO NADP A/B). Again "up and away" to minimize noise
NADP at LFPG (Charles de Gaulle): Maintain T/O thrust to 1500AGL then MAXIMUM CLB thrust to 3000AGL before accelerating. Here specifically they specify that you are not allowed to use reduced CLB thrust. Again compliant with "Up and Away" principle.
As it is already a stated fact that there is economy in selecting full CLB thrust when a continuous climb to above FL150 can be expected, I would like others opinion on making it a standard procedure to also select full CLB thrust wherever you have a NADP AND a continuous climb to above FL150 can be expected.
Any relevant inputs are highly appreciated!
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Safety first, noise after?
Don’t get me wrong, noise is (or will be) an issue everywhere. Safety (some might say “commensurate with noise”) is priority on departure. What can you do to reduce noise and yet remain “safe”?
Are there options available to you which could reduce environmental impact whilst still complying?
Don’t get me wrong, noise is (or will be) an issue everywhere. Safety (some might say “commensurate with noise”) is priority on departure. What can you do to reduce noise and yet remain “safe”?
Are there options available to you which could reduce environmental impact whilst still complying?
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Hi everyone!
In our company we use a standard thrust reduction altitude of 800ft which coincides with a standard acceleration altitude of 800ft also. Under normal departures with a T/O thrust rating including both fixed and assumed derate, the B737 also selects a CLB derate based on T/O thrust. Where a continuous climb can be expected to above FL150 it is recommended to select full CLB thrust for normal departures as it saves fuel.
However during departures with NADP1 or NADP2 we are not allowed to select full climb thrust until NADP is complete at 3000 AGL. At first glance this may seem logical, but I question this procedure. Why not program full CLB thrust during NADP ?
The answer many have given me is (logically) that you want to emit as low noise level as possible. This makes sense and is also according to an ICAO AMC. However the wording in the NADP specifications along with specific departures at certain dense traffic airports leads me to believe we got this all wrong.
Here's my argument:
Sound waves (or light for that matter) are primarily dependent on two main factors. The level of sound and the distance to the observer. If you double the sound level the observer will also observe a doubling of the sound. If you double the distance, the observer will observe a quarter of the sound emitted. It follows an inverse Pythagorean theorem.
With that knowledge it would be fair to assume that the idea behind NADP is to make departing aircrafts fly in such a manner that they would be as far from the noise sensitive area as possible. This can best be achieved by using as high thrust setting as possible so as to maximize the distance to noise sensitive areas. (I assume of course that the noise level between full CLB and CLB1 or CLB2 is very little in comparison)
If you look at the wording in NADP1 as stated by ICAO these procedures basically states that you are not allowed to select CLB thrust earlier than 800 ft, and that you should climb at V2 + 10-20kts until acceleration altitude of minimum 3000 ft AGL. As opposed to normal departure procedures where you can select CLB thurst at 400 ft AGL and clean up threreafter. Again the idea of getting up and away before you need to accelerate to clean up.
Jeppesen route manual also states in conjunction with NADP that aircrafts with FMC calculated thrust are not allowed to use a thrust setting less than that calculated by the FMC during NADP. Again "Keep thrust up" to get up and away from the noise sensitive areas.
Looking at the NADP for LGAV (Athens) states that unless for safety reasons you are not allowed to reduce T/O thrust until a minimum altitude of 1500 AGL (These are based on the older ICAO NADP A/B). Again "up and away" to minimize noise
NADP at LFPG (Charles de Gaulle): Maintain T/O thrust to 1500AGL then MAXIMUM CLB thrust to 3000AGL before accelerating. Here specifically they specify that you are not allowed to use reduced CLB thrust. Again compliant with "Up and Away" principle.
As it is already a stated fact that there is economy in selecting full CLB thrust when a continuous climb to above FL150 can be expected, I would like others opinion on making it a standard procedure to also select full CLB thrust wherever you have a NADP AND a continuous climb to above FL150 can be expected.
Any relevant inputs are highly appreciated!
In our company we use a standard thrust reduction altitude of 800ft which coincides with a standard acceleration altitude of 800ft also. Under normal departures with a T/O thrust rating including both fixed and assumed derate, the B737 also selects a CLB derate based on T/O thrust. Where a continuous climb can be expected to above FL150 it is recommended to select full CLB thrust for normal departures as it saves fuel.
However during departures with NADP1 or NADP2 we are not allowed to select full climb thrust until NADP is complete at 3000 AGL. At first glance this may seem logical, but I question this procedure. Why not program full CLB thrust during NADP ?
The answer many have given me is (logically) that you want to emit as low noise level as possible. This makes sense and is also according to an ICAO AMC. However the wording in the NADP specifications along with specific departures at certain dense traffic airports leads me to believe we got this all wrong.
Here's my argument:
Sound waves (or light for that matter) are primarily dependent on two main factors. The level of sound and the distance to the observer. If you double the sound level the observer will also observe a doubling of the sound. If you double the distance, the observer will observe a quarter of the sound emitted. It follows an inverse Pythagorean theorem.
With that knowledge it would be fair to assume that the idea behind NADP is to make departing aircrafts fly in such a manner that they would be as far from the noise sensitive area as possible. This can best be achieved by using as high thrust setting as possible so as to maximize the distance to noise sensitive areas. (I assume of course that the noise level between full CLB and CLB1 or CLB2 is very little in comparison)
If you look at the wording in NADP1 as stated by ICAO these procedures basically states that you are not allowed to select CLB thrust earlier than 800 ft, and that you should climb at V2 + 10-20kts until acceleration altitude of minimum 3000 ft AGL. As opposed to normal departure procedures where you can select CLB thurst at 400 ft AGL and clean up threreafter. Again the idea of getting up and away before you need to accelerate to clean up.
Jeppesen route manual also states in conjunction with NADP that aircrafts with FMC calculated thrust are not allowed to use a thrust setting less than that calculated by the FMC during NADP. Again "Keep thrust up" to get up and away from the noise sensitive areas.
Looking at the NADP for LGAV (Athens) states that unless for safety reasons you are not allowed to reduce T/O thrust until a minimum altitude of 1500 AGL (These are based on the older ICAO NADP A/B). Again "up and away" to minimize noise
NADP at LFPG (Charles de Gaulle): Maintain T/O thrust to 1500AGL then MAXIMUM CLB thrust to 3000AGL before accelerating. Here specifically they specify that you are not allowed to use reduced CLB thrust. Again compliant with "Up and Away" principle.
As it is already a stated fact that there is economy in selecting full CLB thrust when a continuous climb to above FL150 can be expected, I would like others opinion on making it a standard procedure to also select full CLB thrust wherever you have a NADP AND a continuous climb to above FL150 can be expected.
Any relevant inputs are highly appreciated!
For CDG, where is that stated that max climb thrust should be used? I cannot see that anywhere.
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Just a quick correction:
800ft. Is the MINIMUM altitude for thrust reduction.
Actual reduction can be between 800’ en 3000’
Often, it is still done at 1500’ and does comply with NADP1
There is often a misconception regarding this.
800ft. Is the MINIMUM altitude for thrust reduction.
Actual reduction can be between 800’ en 3000’
Often, it is still done at 1500’ and does comply with NADP1
There is often a misconception regarding this.
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Why would you add another procedure - changing the CLB thrust - at 3000' if you don't have to? There is enough flying to do at that point that you don't need another distraction.
The SOP quoted by the OP doesn't make sense for noise OR safety! A lower CLB thrust will keep you closer to the ground for a longer time and distance. So if you need full CLB instead of CLB1 or CLB2, program it from the start!
The SOP quoted by the OP doesn't make sense for noise OR safety! A lower CLB thrust will keep you closer to the ground for a longer time and distance. So if you need full CLB instead of CLB1 or CLB2, program it from the start!
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Good Egg:
Safety first, noise after?
Don’t get me wrong, noise is (or will be) an issue everywhere. Safety (some might say “commensurate with noise”) is priority on departure. What can you do to reduce noise and yet remain “safe”?
On an all engine departure that complies with climb % gradients what how does noise/thrust reduction effect safety?
Safety first, noise after?
Don’t get me wrong, noise is (or will be) an issue everywhere. Safety (some might say “commensurate with noise”) is priority on departure. What can you do to reduce noise and yet remain “safe”?
On an all engine departure that complies with climb % gradients what how does noise/thrust reduction effect safety?
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IMO, reducing thrust for takeoff reduces safety in that you attain less margin for error than if thrust is maintained at a higher level. That is balanced with the lesser probability of catastrophic engine failure at reduced thrust. However, reducing thrust from FULL T/O thrust may increase safety overall, since engines are not designed to maintain full thrust for very long, and long-term wear is definitely increased.
However, especially when using deep derate + assumed temp reductions (e.g., 25% reduction) for takeoff, I see NO value in reducing thrust further for climb. This is supported by the fact that in the GE CF-6 or GenX engine on the 744/748, CLB (which is essentially equal to Max Continuous) or CLB1 thrust is significantly higher than T/O thrust when using max reduction.
I would like to see the allowable T/O thrust reduction be limited to no less than normal CLB2 derated thrust.
However, especially when using deep derate + assumed temp reductions (e.g., 25% reduction) for takeoff, I see NO value in reducing thrust further for climb. This is supported by the fact that in the GE CF-6 or GenX engine on the 744/748, CLB (which is essentially equal to Max Continuous) or CLB1 thrust is significantly higher than T/O thrust when using max reduction.
I would like to see the allowable T/O thrust reduction be limited to no less than normal CLB2 derated thrust.
