Greetings:

 

1:  Acceleration Height is the transition altitude when the pilot increases takeoff speed plus V2 to climb out speed (250 kias below FL10,000, unless there are constraints).   The acceleration height is usually 1000 feet.

 

2:  Thrust Reduction Altitude is triggered by altitude (or flap settings) and is usually at 1500 feet.  Thrust reduction minimizes engine wear (by minimizing heat build-up in the engines) by changing N1 to climb power.

 

My question:  If you are using European noise abatement procedures which state to fly the aircraft to 3000 feet at takeoff speed plus V2.  Is the acceleration height 3000 feet, and should this be adjusted manually in the CDU?

 

Further, does the thrust reduction height always stay at 1500 feet?

 

I have attached noise abatement documents.

 

Thank you,   WilloW

 

 

 

 

 

triggered by altitude (or flap settings) and is usually at 1500

 

I thought you reduced thrust at 1,000 feet irregardless of flap setting.

 

 

 

Is the acceleration height 3000 feet, and should this be adjusted manually in the CDU?

 

You accelerate up to 250 knots at 3000 feet...

 

You would change the thrust reduction, acceleration altitude, and engine out acceleration height in the FMS if you are using VNAV during takeoff.

Thanks Kenny;

 

So what you are saying is that you ONLY alter the acceleration height and thrust reductions in the CDI if you are planning to use VNAV during the take off and climb sequence.

 

Thanks,   WilloW

No, you adjust thrust reduction accel height depending on what noise abatement Procedure is required, either NADP1 or NADP2 depending on company SOP and the airfield you are departing.

European noise abatement procedures

Can you provide a link to these?

http://www.flaps2approach.com/training/flight-training-b737-aircraft-related/

 

Towards the bottom - Noise Abatement Procedures

Thanks Flex 1978. 

 

I thought this was the case (adjust height reduction altitude to noise abatement), but maintain thrust reduction height of 1500 feet.   

 

I wanted to check to make sure though!     Cheers,  WilloW

Here is the Zurich departure noise procedures which show the variation:

 

 

 

Climb with maximum climb gradient to 4500 ft AMSL:

- use the high lift devices take-off configuration

- take-off power reduction to climb power at 2900 ft AMSL

 

 

The thrust reduction occurring at 2900ft and acceleration 4500ft.

 

This type of information can be found on the Aerodrome AIP.

Thank you.

 

I also made a typo in my opening post.  V2 +20 and NOT take-off +V2.  

 

I understand why the acceleration height will change depending upon noise abatement & other constraints. 

 

But what about the thrust reduction altitude.  Is this height altered?  Considering that this reduction in take off thrust to climb thrust is designed to extent engine life, I'd assume it would always remain at 1500 feet (with the exception of possible rare instances) ??

 

WilloW

 

 

My question: If you are using European noise abatement procedures which state to fly the aircraft to 3000 feet at takeoff speed plus V2. Is the acceleration height 3000 feet, and should this be adjusted manually in the CDU?



Further, does the thrust reduction height always stay at 1500 feet?

 

Hi,

 

I'm mot sure what European noise abatement procedures are, I only know of ICAO NADP 1,2,A and B. Assuming that is what you mean:-

 

1) Yes

 

2) Not quite. NADP 1 and 2 the thrust reduction altitude is 800' (or at least 800' in the case of NADP 2). The former NADP A and B specified 1500' and 1000' respectively.

But what about the thrust reduction altitude.  Is this height altered?  Considering that this reduction in take off thrust to climb thrust is designed to extent engine life, I'd assume it would always remain at 1500 feet (with the exception of possible rare instances) ??

 

 

From the pdf you linked to Iain you can see the thrust reduction height varies on the 'standard' procedures and these are to comply with noise not specifically for engine wear. As noted through this topic both thrust reduction height and acceleration altitudes can be varied by company SOP's and Local Aerodrome requirements indicated in the AIP.

I though that the thrust reduction was at 1500ft whilst at the same time the nose lowers to 10 degrees so that you can accelerate and retract the flaps when required

 

Thomas Wills

Thank you Stephen and others.   I appreciate your time in replying.  

 

My question was not aimed at these exact methods as depicted in the attachment, but was more a general question.  I attached the files as an example  Best,   WilloW

 

 

Not quite. NADP 1 and 2 the thrust reduction altitude is 800'

My bad, it is 800' height, not altitude - duh!

Towards the bottom - Noise Abatement Procedures

Thanks but I wanted a link to the European regulations