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Paul12

Add-drag messages in FMC

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I wonder if those messages also appear in the real world FMC or if it is only a FlightSim function ?

Same with Reset Alt when reaching the point of descent ?

 

Anybody knows ?

 

Hubert Werni

 

 

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I wonder if those messages also appear in the real world FMC or if it is only a FlightSim function ?

Same with Reset Alt when reaching the point of descent ?

 

"ADD DRAG" will appear when the FMC is having difficulty maintaining the descent path to meet a speed constraint.

 

"RESET ALT" is a reminder that the top of descent point is approaching.

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...and this is all information contained in the tutorials.

 

Where exactly ???

 

Hubert Werni

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Open the manuals

 

Hold down the Ctrl and F key together

 

Type Reset Alt

 

Press Enter a few times

 

the PDF reader will show you any and every time the text "Reset Alt" appears in the document.

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"ADD DRAG" will appear when the FMC is having difficulty maintaining the descent path to meet a speed constraint.

The message in the real aircraft is "DRAG REQUIRED". I can't recall exactly what it is in NGX.

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...and this is all information contained in the tutorials.

 I would be too embarrassed to ask any questions, especially those relating to PMDG, without first reading all the info at my disposal, it's simply a matter of pride! Pride, which along with "civility" seems to be evaporating like water in a desert in this "so-called" modern World in which we all live!  

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 I would be too embarrassed to ask any questions, especially those relating to PMDG, without first reading all the info at my disposal, it's simply a matter of pride! Pride, which along with "civility" seems to be evaporating like water in a desert in this "so-called" modern World in which we all live!  

 

May be you should first read my question  of the post which was: does " the message add drag" show in the real world or only on Flight Simulator.

 

Regards

 

Hubert Werni

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No offence intended: The addon was developed according to the real-world aircraft and a number of genuine Boeing manuals are included in the addon documentation.

 

Still this may be a valid question as flightsim addons may offer a number of "cheats" to help the simmer fly the plane. ("autofill" of certain FMC entries, for example)

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 I would be too embarrassed to ask any questions, especially those relating to PMDG, without first reading all the info at my disposal, it's simply a matter of pride! Pride, which along with "civility" seems to be evaporating like water in a desert in this "so-called" modern World in which we all live!  

 

Me,I  would be embarrased to issue dumb remarks before having read and understood  the content of a post.
As to asking questions which may be somewhere in a manual : may be I am not as intelligent as you - or as you think you are -
and therefore  I sometimes do not understand the manual.
This is the reason I am in the Forum and by the way I make contributions.
 
Cheers
 
Hubert Werni

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Reset MCP Altitude

 

This means you are within about 5nm of your Top of Decent point and your MCP (Mode Control Panel) altitude is set to the altitude you are currently at. This means you are only authorizing the autopilot to descend no feet to the altitude it is already maintaining.

 

When you reach the Top of descent point, the aircraft will slow down, hoping that by the time you allow it to descend, it can use the acceleration back to normal speed to get back onto profile.

 

You may need to do this if ATC don't clear you to descend, for instance to avoid hitting the aircraft that is under you or about to pass under you. In this case you will not be able to reach the IAP in LNAV/VNAV and will need to add track miles to get down.

 

It is quite possible to fly overhead your destination at FL410 and then run out of route. The autopilot will NEVER descend below the altitude you have set in the MCP (Because if it did, you might collide in middair and kill everyone on board both your plane and the one you hit).

 

 
 
Add Drag
 
 This is the FMC asking you to add drag. Drag can be added by
  1. Deploying the speedbreak
  2. Deploying flap
  3. Lowering the Landing Gear

There are other unapproved methods of adding drag such as side-slipping, but these are potentially dangerous and may cause damage to the aircraft in some cases.

 

Drag may be required if you are close to the vertical profile, but have too much energy. This is usually caused by an unforecast (See Descent Forecast Page) tailwind.

 

It can also be caused by being slow on the MCP altitude, or by a VNAV profile that is too steep (This may happen in some locations due to the STAR profile being steeper than the most efficient profile, but is more likely to be due to the unforecast tailwind, or a forecast headwind that doesn't eventuate).

 

To avoid seeing this - Always add a descent forecast wind profile. However sometimes the forecast isn't exactly what actually happens, and in those situations you may need to add a bit of drag.

 

Before you reach down and grab the speedbrake handle though, have a look at the trending information. The FMC will immediately go "Drag Required" on you the minute it detects that it's going a bit too fast, but if you notice your speed decreasing anyway (especially if you are near the 10,000ft mark) you may find that the aircraft can still make the restriction, but may just be slowing down a little too slowly for the FMC to like it. I have often ignored the profile if it means we will be 250kts by 9500ft anyway. No point pulling brakes now and then adding thrust later.

 

Remember the FMC has a programmed profile it wants. It is based on computer models and predictions, but sometimes the atmosphere of planet earth does things like change wind direction without the FMC expecting it Use your judgement to figure out if you need to do something to get back on profile, and then do that thing. Obey ATC, don't hit any traffic or cause breakdowns of separation (Especially unauthorized things that ATC don't want you to do)

 

The FMC messages are telling you "If you don't change something, we will be high and/or fast"

 

There's one more similar message related, something like "Descent path unachievable"

 

This is basically the FMC saying "Your telling me you want to go from 300kts at FL180 to "on the ground and stopped" in 15 miles? That's not possible."

The FMC will try to do what it's been told to do, but it can't break the laws of physics.

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Reset MCP Altitude

 

This means you are within about 5nm of your Top of Decent point and your MCP (Mode Control Panel) altitude is set to the altitude you are currently at. This means you are only authorizing the autopilot to descend no feet to the altitude it is already maintaining.

 

When you reach the Top of descent point, the aircraft will slow down, hoping that by the time you allow it to descend, it can use the acceleration back to normal speed to get back onto profile.

 

You may need to do this if ATC don't clear you to descend, for instance to avoid hitting the aircraft that is under you or about to pass under you. In this case you will not be able to reach the IAP in LNAV/VNAV and will need to add track miles to get down.

 

It is quite possible to fly overhead your destination at FL410 and then run out of route. The autopilot will NEVER descend below the altitude you have set in the MCP (Because if it did, you might collide in middair and kill everyone on board both your plane and the one you hit).

 

 
 
Add Drag
 
 This is the FMC asking you to add drag. Drag can be added by
  1. Deploying the speedbreak
  2. Deploying flap
  3. Lowering the Landing Gear

There are other unapproved methods of adding drag such as side-slipping, but these are potentially dangerous and may cause damage to the aircraft in some cases.

 

Drag may be required if you are close to the vertical profile, but have too much energy. This is usually caused by an unforecast (See Descent Forecast Page) tailwind.

 

It can also be caused by being slow on the MCP altitude, or by a VNAV profile that is too steep (This may happen in some locations due to the STAR profile being steeper than the most efficient profile, but is more likely to be due to the unforecast tailwind, or a forecast headwind that doesn't eventuate).

 

To avoid seeing this - Always add a descent forecast wind profile. However sometimes the forecast isn't exactly what actually happens, and in those situations you may need to add a bit of drag.

 

Before you reach down and grab the speedbrake handle though, have a look at the trending information. The FMC will immediately go "Drag Required" on you the minute it detects that it's going a bit too fast, but if you notice your speed decreasing anyway (especially if you are near the 10,000ft mark) you may find that the aircraft can still make the restriction, but may just be slowing down a little too slowly for the FMC to like it. I have often ignored the profile if it means we will be 250kts by 9500ft anyway. No point pulling brakes now and then adding thrust later.

 

Remember the FMC has a programmed profile it wants. It is based on computer models and predictions, but sometimes the atmosphere of planet earth does things like change wind direction without the FMC expecting it Use your judgement to figure out if you need to do something to get back on profile, and then do that thing. Obey ATC, don't hit any traffic or cause breakdowns of separation (Especially unauthorized things that ATC don't want you to do)

 

The FMC messages are telling you "If you don't change something, we will be high and/or fast"

 

There's one more similar message related, something like "Descent path unachievable"

 

This is basically the FMC saying "Your telling me you want to go from 300kts at FL180 to "on the ground and stopped" in 15 miles? That's not possible."

 

The FMC will try to do what it's been told to do, but it can't break the laws of physics.

  

  Thank you very much for your superb answer and explanation.

 As I mentioned before I wanted to know if those CDU messages appear in the real world airplanes.I assumed that is the case

 but wanted it confirmed.

I am surprised how certain people freak out because a question asked my be found somewhere in manuals,google,YouTube etc etc

First: As I am convinced that any question can be found somewhere else then why having a Forum ?

  Second: nobody asked them to answer.

 Third: I support this superb forum with small donations.

 

 Cheers

 

Hubert Werni

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First: As I am convinced that any question can be found somewhere else then why having a Forum ?

 

The forum could actually be discussing more interesting things than the same things over and over again if people actually read the answer.  A lot of people equate forum with Help Desk for some reason.  Clearly, if we weren't here answering the same 12 questions over and over, we'd all be sitting here with nothing to talk about, right?  Wrong.  We could be discussing why the AP has so many different modes, or different techniques to fly the plane better.  Heck, if everyone at least glanced at the intro manual and tutorials, we could at least answer the more detailed questions where people have to e

 

Also, you have to admit, it kinda grates your nerves when you've written it somewhere and someone ignores the help you've provided by writing it and asks the question again.  This, of course, forces someone to write it all over again.

 

It also introduces human error into the information.  Each time someone repeats the original information from the manual, certain aspects of the original info may be compromised.  See: Chinese Whispers.

 

In pictures and diagrams:

 

 

 


Second: nobody asked them to answer.

 

Sure, but you can't blame them for jumping in and saying where the information is.  Contrary to popular forum belief, it is actually helpful to point out where the information is.  It's just more work for the recipient than they wanted.

 

Maybe I'm just a mean old cuss because my parents always just told me to go look things up in our set of encyclopedias.  I was brutally forced to go learn things on my own, and ended up learning about more things in the process.

 

Repressed childhood memories eventually made me into the RTFM guy.

 

 

 


Third: I support this superb forum with small donations.

 

None of those donations make it to the people who are actually providing answers or the location of the information (not that they should).  So, while I'm glad you support AVSIM, a donation to them doesn't mean you're entitled to have people find the information for you.

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The message in the real aircraft is "DRAG REQUIRED". I can't recall exactly what it is in NGX.

It's that

 

Sent from my Nexus 4 using Tapatalk

 

 

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Maybe I'm just a mean old cuss because my parents always just told me to go look things up in our set of encyclopedias.  I was brutally forced to go learn things on my own, and ended up learning about more things in the process.

 

Repressed childhood memories eventually made me into the RTFM guy.

 

As an observer who purposefully didn't invest anything into this forum, I think "The RTFM guy" is a much too kind description for what you are.  You should be kind.

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The message in the real aircraft is "DRAG REQUIRED". I can't recall exactly what it is in NGX.

 

Nothing in our FMC is worded differently from the real thing. There is a big list of the possible messages in the FCOM 2.

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Wow ! All that poncing on by somebody who obviously loves the sound of his own voice, just to answer a simple question.

 

Sent from my GT-N7100 using Tapatalk

 

 

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As an observer who purposefully didn't invest anything into this forum, I think "The RTFM guy" is a much too kind description for what you are.  You should be kind.

 

I didn't realize asking people to invest in their own knowledge was unkind.  Silly me.

 

 

 

All that poncing on by somebody who obviously loves the sound of his own voice, just to answer a simple question.

 

If you're referring to me, you'll note my original response both answered the question, and was brief (therefore wouldn't really indicate I enjoy hearing my own voice...which, in fact, I rather hate).

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As an observer who purposefully didn't invest anything into this forum, I think "The RTFM guy" is a much too kind description for what you are. You should be kind.

 

I would say he should be funnier and more sarcastic...

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If you're referring to me, you'll note my original response both answered the question, and was brief (therefore wouldn't really indicate I enjoy hearing my own voice...which, in fact, I rather hate).

I make a comment .... "All that poncing on by somebody " .... and yes, you reply, because you are the only one in this thread that realised it was you that had decided to ponce on the OP and you know it.

 

And yes, I noticed your "original" (btw should read "initial" ) response both answered the question and as you say, in a brief manner. But have you considered that the answer had already been answered, almost two days earlier? Factually? And in a manner that suggested "here to help", rather than "read the manual"? There was absolutely no need for you to intervene and in the process make the OP feel uncomfortable, which he obviously did. If you don't want to help, it may have been better in this case to just keep fingers away from keyboard before engaging brain.

 

Secondly, (and seeing that you mention it), you state ..... ("therefore wouldn't really indicate I enjoy hearing my own voice"). So now you jump in with a whole pile of rubbish that is totally irrelevant to the OP's original question - just to enable you to feel that you have scored some more points !?! Mate, get a life and start to treat people with some respect.

 

And finally, your parting comment ("..... which in fact I rather hate"). That does not surprise me in the least. Maybe, if you showed some good manners rather than jumping on people before engaging brain, you may start to like the sound of your own voice just a little more.

 

Sorry to be so honest with my comments, it's just that a certain thread within Avsim about the attitude of some members within the PMDG forum made you spring to mind. That in itself is a shame, because I know you have a lot of knowledge. Share it nicely.

 

Dave B

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Is there a forum rule where your not allowed to ask a question if that answer can be found somewhere in the documentation provided by PMDG?

 

Or is the answer to that in the manuals?

 

Get a grip it's a forum!!!

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And yes, I noticed your "original" (btw should read "initial" ) response both answered the question and as you say, in a brief manner. But have you considered that the answer had already been answered, almost two days earlier? Factually? And in a manner that suggested "here to help", rather than "read the manual"? There was absolutely no need for you to intervene and in the process make the OP feel uncomfortable, which he obviously did. If you don't want to help, it may have been better in this case to just keep fingers away from keyboard before engaging brain.

 

First, orginial and initial are synonyms, so I'm not sure what you're getting at.  My original post and the original post are two separate concepts, if your point was to try and get on my case about forum slang.

 

I did see that someone had answered the question, but as the manual also answers these questions, I thought I'd add it in.  Why?  Because some people don't know that the manuals are there and that they're actually worth something.  Why?  Because answering people's questions here in the forum is nice and helpful, and pointing out that the manuals exist is apparently mean and evil (despite the manual generally containing the more accurate, and more detailed answer).

 

Why is this the case?  I have no idea.  Perhaps because people read all kinds of extra things into answers of "read the manual."  It's seen as dismissive for whatever reasons I still don't understand, particularly because I normally also provide the answer when I say that it's contained in the manual (but didn't in this case for the exact reason you pointed out - the answer was already given).

 

 

 


Secondly, (and seeing that you mention it), you state ..... ("therefore wouldn't really indicate I enjoy hearing my own voice"). So now you jump in with a whole pile of rubbish that is totally irrelevant to the OP's original question - just to enable you to feel that you have scored some more points !?! Mate, get a life and start to treat people with some respect.

 

If the forum game were all about points, I'd be pretty far in the red, but I'd be okay with that.  Sadly, there are those here who would vote posts down simply because they don't like the answer, no matter how factual it is.  Further, I was only responding to someone questioning my points.  There would be no reason for me to have said anything if people just let the initial comment go.

 

The information is actually in the manuals, too.

Fact.

Done.

 

Any time I bring up the manuals, it's simply to point out that they are actually useful and contain a lot of the information that people post about.

 

Searching the manual is quicker and generally more accurate.

...but my attempts to save people time and frustration (and the work of typing and posting) are apparently evil for some reason.  Shame on me.

 

"Mate, get a life and start to treat people with some respect."

 

^ Most ironic statement of the year.  Last I checked, I didn't attack anyone personally like you just did, so where my lack of respect exists, I'm genuinely curious.

 

 

 


And finally, your parting comment ("..... which in fact I rather hate"). That does not surprise me in the least. Maybe, if you showed some good manners rather than jumping on people before engaging brain, you may start to like the sound of your own voice just a little more.

 

Again, I find your assertions ironic based on the way in which I'm being told that I'm apparently pretty mean...in a manner that's more personally inflammatory than any of my posts here.

 

In any case, I was referring to the tonal quality of my voice, and not the content of the message.

 

 

 


Sorry to be so honest with my comments, it's just that a certain thread within Avsim about the attitude of some members within the PMDG forum made you spring to mind. That in itself is a shame, because I know you have a lot of knowledge. Share it nicely.

 

I'm still at a loss to where I was mean to anyone.

 

In any case, there's no need to apologize, really.  People don't like my matter-of-fact posting.  I can't blame them for that.  I'll try to say over and over that it's the fact that this is text, and you can't hear my intonation, but the end story is that it puts people off.  While I can control what I say, I can't control how people react to it.

 

 

 


Is there a forum rule where your not allowed to ask a question if that answer can be found somewhere in the documentation provided by PMDG?

 

I don't recall ever claiming that there was one.  I simply stated that it's better for the community in general if people actually tried reading the manual for the basic stuff.

 

 

 


Or is the answer to that in the manuals?

 

Nope.  That is not in the manuals.

 

 

 


Get a grip it's a forum!!!

 

Correct.

 

Last I checked, a forum is for discussion in general, and not necessarily a help desk.  Could it be used as one?  Certainly.  Does that mean that pointing out that there's a search function, or the answer is in the manuals is unhelpful?  No.

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