Remys

PMDG 777 Struggling Through Descend

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Hello Guys,

 

I do have one question, I am always Struggling through the Descend Phase as if it not really managed, I always have to drag and adjust manually the descend rate ......... speed breaks most of the time extended and speed takes time to slow down. in the real thing, things don't go that way.

 

any suggestion, any solution, Am I missing something ? 

 

thanking you in advance

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Might be an issue with real world weather and the aircraft not having the information.

 

If you use the T7 with real weather (like AS2016 or something) you will need to enter the winds at altitude data into the flight management system...

 

As I understand it, the manual explains how to do this...

 

A

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Might be an issue with real world weather and the aircraft not having the information.

 

If you use the T7 with real weather (like AS2016 or something) you will need to enter the winds at altitude data into the flight management system...

 

As I understand it, the manual explains how to do this...

 

A

Hello,

I am using PFPXalong with ASN and Uploading the Wind and Altitude into the FMC. Upload Wind Data Link. do not face any problem during climb just during descend. Drag all the time message from FMC and spoilers 90% retracted too .... I am really out of options during the descend phase.

 

PS: I am Flying the 777 300 [PFPX and ASN]

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Hello,

I am using PFPXalong with ASN and Uploading the Wind and Altitude into the FMC. Upload Wind Data Link. do not face any problem during climb just during descend. Drag all the time message from FMC and spoilers 90% retracted too .... I am really out of options during the descend phase.

 

PS: I am Flying the 777 300 [PFPX and ASN]

 

Where are your hardware throttles when all of this is happening?

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Where are your hardware throttles when all of this is happening?

my hardware throttle mid position but the autopilot sets them to Idle, so Ihave Idle displayed. no throttle power engines at Idle thrust

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my hardware throttle mid position but the autopilot sets them to Idle, so Ihave Idle displayed. no throttle power engines at Idle thrust

 

Not entirely true.

 

The autothrottle will set them to idle, but then the mode reverts to HOLD. HOLD mode allows the throttles to be manually manipulated. In the real aircraft, the throttles are servo driven back to the idle position. Yours aren't. Manually move them to idle prior to TD and I'm willing to bet that the issue disappears.

 

If you'd prefer not to worry about it, you can change the AT hardware override setting via MENU > PMDG SETUP > SIMULATION (on the CDU).

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Yours aren't. Manually move them to idle prior to TD and I'm willing to bet that the issue disappears

 

I will try a short Flight now and will move the throttles to idle position manually before initiating the Descend and will let you know with the outcome. finger crossed :)

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Yeah, this is a common problem because idle N1 is not the same at FL320/0.80M as on the ground.  The sure indication is your fuel flow which should be about 3.2 lbs x 1000 / hr.

 

I always use the override in hold/arm option and show position when moving, and make sure the throttle controller is on the idle stop.  A quick nudge of the throttles while in hold you can see the moving blue arc to confirm aircraft throttles are idle.

 

Another consideration is your descent airspeed.  I usually change the default ECON value such as 314 KIAS to a STAR speed constraint such as 280, and the speed may increase to 290+ but I let it go until approach the published constraint.  Usually, the V/S has decreased before then and she is slowing on her own and only a few miles of speedbrakes are required.  This is part of energy management, which is something that is a major factor in flying a big heavy.

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Might be an issue with real world weather and the aircraft not having the information.

 

If you use the T7 with real weather (like AS2016 or something) you will need to enter the winds at altitude data into the flight management system...

Yours aren't. Manually move them to idle prior to TD and I'm willing to bet that the issue disappears

 

I would like to Thank you for you great Help and Support. Actually I did three test flights and they worked as a charm:

problems that I was facing and solution as given has been adapted:

1- my first error is that I was just uploading the CLB Wind Data and not uploading the Winds for the Descend, so I upload it to the FMC

   

2- Setting Throttle to Idle Prior to TD

these two things saved my life didnt even had to Drag.

 

On Another Hand I do have some clarification on 4 issues listed below:

 

1- I am not having correct readings for the TAT for instance it is displaying +26 C on a level of 280 attached is the screenshot whereas it should at least be -27 C

2- Getting Insufficient Fuel from FMC although I have the right profiles in PFPX unless there's an updated profile for PMDG 777 300 [using PFPX 1.28]

3- Flight Plan from PFPX new version not loading Correctly [ I am manually adjusting the Plan]

4- Unable to fligh cruise altitude although it should be able [but i believe that this error is from the FP exported from PFPX] I believe that I have to adjust all of the airways and stuff manually in order to have a proper plan

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I am also facing now a new problem. after landing Autoland, the autopilot won't disconnect in any way. whatever I do it remains active ........... very weird issue never experienced it

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Please don't double post the same topic.

 

Regarding TAT, -26C might be the SAT but TAT is usually around -10 to -5C at the FL300 region.  Higher temperature is always a weather engine problem, what are you using?

 

I've not had problems with PFPX fuel predictions but again this can be weather related. Is it using the same winds aloft as the flight?  And I see the remaining are PFPX related. They have an active forum over at Aerosoft and the manual is very complete.  Most of us here don't mind answering one or two questions about other products but your questions reveal you need more than that.

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You are completely right. PFPx and other issues not related to PMDG 777 are not to be written or posted here.

 

but regarding the Temperature, for instance In otherplanes, lets Say FsLAb A320 it givess like : TAT: -27, SAT: -24 , ISA +1 at FL of 280 same value as ASN. I was just wondering how to read the real external Temp on the PMDG 777 . 

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. I was just wondering how to read the real external Temp on the PMDG 777 .

 

The SAT is available in the FMC.., check PROG page 2.

 

Are you familiar with TAT?  It's not a tattoo in this context, just Google "total air temperature."  Airspeed has everything to do with the measurement.

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uploading the CLB Wind Data

There is no CLB Wind Data that I am aware of. Where did you get this from? It's either cruise or descent forecasted winds.

 

Unable to fligh cruise altitude although it should be able

An updated profile will make no difference. PFPX has a tendency to pick altitudes that are very close to the top of optimum altitude. Go with what the FMC says and not what PFPX says. Sometimes I have seen it planning steps climbs that are above the maximum altitude.

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On 9/26/2016 at 3:14 PM, scandinavian13 said:

If you'd prefer not to worry about it, you can change the AT hardware override setting via MENU > PMDG SETUP > SIMULATION (on the CDU

in the PMDG Menu I should Set the A/T Manual Override to:

1- Always

2- In Hold Mode Only

3- Never

 

Which Option Should I Choose. [and Should I Also Set Trim Manually to Idle] Honestly I prefer to let the plane manage the Throttles during descend phase to avoid the problem 

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23 minutes ago, Remys said:

Which Option Should I Choose. [and Should I Also Set Trim Manually to Idle] Honestly I prefer to let the plane manage the Throttles during descend phase to avoid the problem

I'm confused by this. Trim to idle? Idle is your throttle setting. Trim is different.

You should choose the option that best fits what you want:

  1. Always - For servo-driven hardware that is always kept in sync with your sim (very few people have this, so this probably isn't for you)
  2. In HOLD mode only - For people who want the most balance of realism, and functionality. HOLD mode usually comes into play during the takeoff roll (where you'd bring the throttles back to idle to reject a takeoff), and during descent (where you can bring the throttles up off the IDLE stop to shallow the descent out some, if necessary).
  3. Never - If you want it to behave like the default aircraft (not as realistic, but you don't have to worry about your hardware's position)

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2 hours ago, Remys said:

Which Option Should I Choose. [and Should I Also Set Trim Manually to Idle] Honestly I prefer to let the plane manage the Throttles during descend phase to avoid the problem 

I always select override to HOLD (or ARM) Only for one simple reason.  In reality the hold mode is where the throttle levers are no longer driven by servos and the pilot is free to move them without overcoming A/T servo commands (which is always available of course).  The only caution when using this mode is to leave the throttles alone during TO/GA takeoff because if you accidentally nudge them you may cancel TO/GA, and to be sure you move the levers to idle before you start the VNAV descent because after the thrust is retarded and the mode changes to ARM then any movement of your controller may add thrust.

More importantly, this mode allows me to use FLCH to manage descents and this is very important in the PMDG 777 because the vertical path is not as accurate as the NGX or 744v3 and I do like to override VNAV if it is not behaving.  For example, descending at a nice 2300 fpm on path until passing a fix then suddenly I'm 1300 feet above path and it will command 3000 fpm descent or switch to VNAV SPD mode and never recover.  This is when I just press the FLCH button and use thrust to modulate the descent.  By modulate the descent I mean use thrust to set the desired descent rate while pitch is controlled by the MCP SPD setting.  This is much preferred method to V/S, which I have mostly abandoned.

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On 5/28/2017 at 11:03 PM, downscc said:

I always select override to HOLD (or ARM) Only for one simple reason.  In reality the hold mode is where the throttle levers are no longer driven by servos and the pilot is free to move them without overcoming A/T servo commands (which is always available of course).  The only caution when using this mode is to leave the throttles alone during TO/GA takeoff because if you accidentally nudge them you may cancel TO/GA, and to be sure you move the levers to idle before you start the VNAV descent because after the thrust is retarded and the mode changes to ARM then any movement of your controller may add thrust.

More importantly, this mode allows me to use FLCH to manage descents and this is very important in the PMDG 777 because the vertical path is not as accurate as the NGX or 744v3 and I do like to override VNAV if it is not behaving.  For example, descending at a nice 2300 fpm on path until passing a fix then suddenly I'm 1300 feet above path and it will command 3000 fpm descent or switch to VNAV SPD mode and never recover.  This is when I just press the FLCH button and use thrust to modulate the descent.  By modulate the descent I mean use thrust to set the desired descent rate while pitch is controlled by the MCP SPD setting.  This is much preferred method to V/S, which I have mostly abandoned.

7

Hello, I tried the override to HOLD (or ARM) in the 777 and 747, the hardware was not controlling the throttles anymore and during descend although I move the hardware to idle, in both planes 747 and 777 the throttle doesn't move and always requires drag.

Any suggestion why this is happening?

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2 minutes ago, Remys said:

Hello, I tried the override to HOLD (or ARM) in the 777 and 747, the hardware was not controlling the throttles anymore and during descend although I move the hardware to idle, in both planes 747 and 777 the throttle doesn't move and always requires drag.

Any suggestion why this is happening?

Use the option that shows your hardware throttle controller position on the N1 gauge, and use that to tell if the program is sensing your closing your throttles. I usually make sure my throttles are closed before TOD.  The B736 is the only variant I've found that has a problem remaining in retard and not getting closed and ARMed.  The 777 and 747 do not have a problem.  The position indicator might help.

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16 hours ago, downscc said:
16 hours ago, downscc said:

Use the option that shows your hardware throttle controller position on the N1 gauge, and use that to tell if the program is sensing your closing your throttles. I usually make sure my throttles are closed before TOD.  The B736 is the only variant I've found that has a problem remaining in retard and not getting closed and ARMed.  The 777 and 747 do not have a problem.  The position indicator might help

 

 

Hello, I have this Option [Showing N1 Gauge]. but During Descend When the Plane is in Hold Mode, I can Move the Throttle, but whenever I am in the approach autoland phase, no matter what I do I cannot move the Throttles the servo is controlling them. is there a way to overpass this problem during approach, cause sometimes I need to push the throttles and give up the final approach unfortunately 

In Real World What Configuration do the pilots use? for 747 and 777

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On 5/28/2017 at 9:02 PM, scandinavian13 said:
  • Always - For servo-driven hardware that is always kept in sync with your sim (very few people have this, so this probably isn't for you)
  • In HOLD mode only - For people who want the most balance of realism, and functionality. HOLD mode usually comes into play during the takeoff roll (where you'd bring the throttles back to idle to reject a takeoff), and during descent (where you can bring the throttles up off the IDLE stop to shallow the descent out some, if necessary).
  • Never - If you want it to behave like the default aircraft (not as realistic, but you don't have to worry about your hardware's position)

Hello,

 During Descend When the Plane is in Hold Mode, I can Move the Throttle, but whenever I am in the approach autoland phase, no matter what I do I cannot move the Throttles the servo is controlling them. is there a way to overpass this problem during approach, cause sometimes I need to abort and add thrust but the throttles remain controlled by the servo 

 

In Real World What Configuration do the pilots use? for 747 and 777

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Remy, you have lost me.  Your problem was with descent but now it is in approach mode.  A second question before you acknowledge you have a solution to the first.

Use A/T Disconnect to manually control the throttles, PMDG provides an ability to program a key command to that so you can use the keyboard or with FSUIPC assign it to a button on your controller.  You can also control descent rate with thrust in FLCH mode with A/T engaged.

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1 hour ago, downscc said:

Remy, you have lost me.  Your problem was with descent but now it is in approach mode.  A second question before you acknowledge you have a solution to the first.

Use A/T Disconnect to manually control the throttles, PMDG provides an ability to program a key command to that so you can use the keyboard or with FSUIPC assign it to a button on your controller.  You can also control descent rate with thrust in FLCH mode with A/T engaged.

Hello,

I will give you the exact description. [ the problem with the descent mode has been fixed], I was able to move the throttles while in hold mode. the only problem remaining is during final approach. when the plane is set to Approach mode, [Aproach Engaged I can select the speed via the MCP but in this mode if I move the hardware it doesn't impact in any way the throttles. they remain controlled by the servo.

this is the only remaining problem which I am trying to find a solution to., [three Autopilot button are green and the plane is in landing mode following the glide slope] the A/T is also on so as to follow the desired speed on the MCP. I keep it on so the plane can maintain the selected speed. but on the other hand, I am trying to check how to bypass the A/T speed in case I want to abort the approach. because by moving the throttles on the hardware they cause no impact on the throttles as if nothing happened

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Once you are in the terminal area you will usually abandon VNAV and switch to usually FLCH, perhaps SPD and ALT. I usually just use FLCH all the way to final if able.

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On 2.6.2017 at 8:10 PM, Remys said:

Hello,

I will give you the exact description. [ the problem with the descent mode has been fixed], I was able to move the throttles while in hold mode. the only problem remaining is during final approach. when the plane is set to Approach mode, [Aproach Engaged I can select the speed via the MCP but in this mode if I move the hardware it doesn't impact in any way the throttles. they remain controlled by the servo.

this is the only remaining problem which I am trying to find a solution to., [three Autopilot button are green and the plane is in landing mode following the glide slope] the A/T is also on so as to follow the desired speed on the MCP. I keep it on so the plane can maintain the selected speed. but on the other hand, I am trying to check how to bypass the A/T speed in case I want to abort the approach. because by moving the throttles on the hardware they cause no impact on the throttles as if nothing happened

Like you stated yourself, you set the A/T throttle override setting to HOLD mode only.

This clearly is exactly as it says. Your throttles will override the A/T only in HOLD mode. When you are landing, you can see from your PFD that your A/T is not in the HOLD mode. So, obviously your throttles do not override the A/T thus don't work.

If you want your throttles always to override A/T, then change the setting to Always. However, in this case, your throttles will always override the A/T and it could create you lots of problems.

Boeing stated that the 777 should always be flown with A/T on. If you want to abort the approach, hit TOGA. If you feel that you need more thrust, increase your speed by few knots from the speed selector in MCP.

Really, no problem :ph34r:

 

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