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hkhoanguyen

Derated Take Off Options

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Hi,

I would like to ask that why D-TO 1 and D-TO 2 are disabled in PERF calc page ? 

Thanks 

Edited by hkhoanguyen

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Could you specify that question? 

Airplane?

What do you mean by „disabled“?

There‘s an option in the pmdg menu in the FMS to enable/disable that feature in the aircraft equipment options as not ever airline allows derated thrust and might disable it.

 

if you mean the EFB in the 747-8 it‘s because PMDG does not have the data to do it properly. And then they don‘t implement it at all rather than doing it not correctly.

Edited by Ephedrin

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PMDG has said (or others have said, I am not sure) that the cost of the data is prohibitive....like $400k per year or something of that scale.  So its not available.  Here's my suggestion....Assumed temp 65.  TO1, CLB 2.  You mostly make it on all runways over 8000ft, at elevation below 2000 ft and no big mountains in front of you.  Fun times!


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ooooor you could just calculated the maximum possible assumed temperature for your weight which is way more accurate than guessing.


Martin von Dombrowski

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I agree with Martin.  Also, why use derate?  In a quad jet the derates are only used when there is an engine out or contaminated runway.  Stick to TO or DTO.  Step one:  Calculate TO thrust takeoff.  Step two increase OAT until takeoff cannot be calculated then pick a value lower that works.  This ignores important considerations such as engine out obstacle clearance but the interested may use NOTAMs to declare these.

Edited by downscc

Dan Downs KCRP

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33 minutes ago, Ephedrin said:

if you mean the EFB in the 747-8 it‘s because PMDG does not have the data to do it properly. And then they don‘t implement it at all rather than doing it not correctly.

This is not true. We never said we will not implement this at all. We said we couldn't have it ready (and correct) at the release date but we will implement it in a future update. The same stands for EFB assumed temperature calculations.

Having readily available data, as mentioned, is a problem, but will not prevent implementation.

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Michael Frantzeskakis
Precision Manuals Development Group
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58 minutes ago, mfrantz said:

This is not true. We never said we will not implement this at all. We said we couldn't have it ready (and correct) at the release date but we will implement it in a future update. The same stands for EFB assumed temperature calculations.

Having readily available data, as mentioned, is a problem, but will not prevent implementation.

Oh... while reading back the words that I actually used I see that I said something quite different from what I wanted to say. Yes, „at the moment“ is missing in my answer but turns the outcome wrong. 

At least I was right with the fact that PMDG wouldn‘t implement something on purpose that‘s not correct just to fake a feature 😄 

I‘m going to give the correct answer in the future xD


,

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1 hour ago, downscc said:

I agree with Martin.  Also, why use derate?  In a quad jet the derates are only used when there is an engine out or contaminated runway.  Stick to TO or DTO.  Step one:  Calculate TO thrust takeoff.  Step two increase OAT until takeoff cannot be calculated then pick a value lower that works.  This ignores important considerations such as engine out obstacle clearance but the interested may use NOTAMs to declare these.

Dan I'm sorry,

You have a complete wrong information.

90% we always use assumed temperatures, assumed temperatures combined with D-TO1 X D-TO2, D-TO1 X D-TO2 and very rare TO.

This issue as Michael pointed out was discussed many times internally. These t.o. calculations are very complex and many airlines even they have on their 744 and 748  EFBs this function might be available.

Usually 90% when they release you, on your paperwork package you will have that information available or they will ACARS you the final data.


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2 hours ago, downscc said:

I agree with Martin.  Also, why use derate?  In a quad jet the derates are only used when there is an engine out or contaminated runway.  Stick to TO or DTO.  Step one:  Calculate TO thrust takeoff.  Step two increase OAT until takeoff cannot be calculated then pick a value lower that works.  This ignores important considerations such as engine out obstacle clearance but the interested may use NOTAMs to declare these.

Actually we use TO1 and TO2 all the time.


Brian Thibodeaux | B747-400/8 First Officer, C-130 Flight Engineer, ATP, CFI

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De-rates with assumed temp are usual depending mostly on gross weight, notwithstanding other perf factors.

But obviously if you’re always flying heavy, you’re almost never going to be derating or assumed temp,especially at hot airports.


Brian Nellis

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As far as I understand by using derates in certain conditions TOW can be even  INCREASED due to the possibility of choosing lower V1   (due to lower VMCG)

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Thanks guys for info, i will wait for the next update then.

14 hours ago, Ephedrin said:

Could you specify that question? 

Airplane?

What do you mean by „disabled“?

There‘s an option in the pmdg menu in the FMS to enable/disable that feature in the aircraft equipment options as not ever airline allows derated thrust and might disable it.

 

if you mean the EFB in the 747-8 it‘s because PMDG does not have the data to do it properly. And then they don‘t implement it at all rather than doing it not correctly.

Hi, first my bad for not being clear in the question I thought that everyone would understand that because only Pmdg 748 has EFB Perf Calculation, and disabled means not being able to select DTO 1 and 2 😄

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