VNAV fail

[downscc 1,327]

Just now, Pricelss said:

It is but what was your final cruise before TOD? 

As stated, FL350.  Do you think being at FL410 is going to make a difference?

[Pricelss 2]

I honestly have no clue as to how the descent path got replaced and completely screwed up. Of all the 74 flights i do it appears it is only happening in which i am at a cruise at FL410 before TOD as it has only happened on Eastbound flights. Im about an hour and a half out from BNE and cruising at FL400 so we will see if it does it on the descent into BNE. If it comes up and its due to a  corrupt panel state then i can just do a repair from the installer and that should fix the dll or whatever file is messed up right? 

AS far as it being at FL410 I am unsure of but it seems to only happen that high. 

[downscc 1,327]

1 hour ago, Pricelss said:

AS far as it being at FL410 I am unsure of but it seems to only happen that high. 

Gave that a try too.  Loaded the scenario as before but changed from LNAV/VNAV to HDG/ALT and flew 40 nm NW STU while dumping payload and climbing to FL410.  Turned inbound to STU and fixed up LEGs page such that I have STU..NUMPT..OKESI..BEDEK.OCK2F setup with 14000 set for BEDEK.  TOD is 8 nm before NUMPO and I activate DES NOW 20 nm before TOD with descent speed set as before (.84/280).  She responds exactly as expected, holds enough thrust to descent at 1500-1600 fpm.

I pulled the thrust to idle and the descent rate increased to 4500 fpm in the thinner air above FL390 so it seems reasonable that you could see 5000 fpm if you are in HOLD | LNAV | VNAV SPD mode and your throttle controller has a noise spike that forces the aircraft throttle from a thrust to maintain 1500-1600 fpm to idle.  At idle at high altitudes you are coming down fast to maintain .84 or even .86 (you didn't mention what you had set for speeds).  It does not explain why the FMS dumped the vertical path prediction.  Something did that and we are trying to figure out what that was.  I was able to increase thrust after the experiment with idle to achieve 500 fpm descent until capturing the path and she automatically switched back into the VNAV modes as expected.

Two things to look for Lee, first why is your throttle spiking and second what is removing the path prediction from the FMS?

[Pricelss 2]

4 hours ago, downscc said:

Two things to look for Lee, first why is your throttle spiking and second what is removing the path prediction from the FMS?

 

Throttle spike i am unsure of. I have on my throttle full so theres no manual override, and even if there was an attempt, manual override has been turned off in the FMS settings. 2nd im not removing the path? All I did was add the restriction in for BEDEK at 250/14000. When i landed at LAX the yesterday i did the same for the SADDE8. 250/11000 and it dumped them. Could it be the edits before TOD causing the dump?

[Ephedrin 418]

Lee,

on your next flight, could you please post a screenshot of your 

- PERF INIT page

- Routes page 1 and 2

- the LEGS page AFTER you have edited the constraints?

 

I have a suspicion...

[Pricelss 2]

Will do. Itll be later tonight. Pages 1 and 2 before take off?

[Ephedrin 418]

1 minute ago, Pricelss said:

Will do. Itll be later tonight. Pages 1 and 2 before take off?

doesn't matter but it actually shouldn't change anyway...

[Pricelss 2]

Roger Doger

[Pricelss 2]

https://www.dropbox.com/sh/rc12yja2fcszwe9/AAD1Wbjezk6zTFUhHJA6rHRMa?dl=0

as requested @Ephedrin

[Ephedrin 418]

I guess on this flight everything went well?

There's actually nothing wrong with the setup.. 

[Pricelss 2]

I dont know yet im still in cruise. Im somewhere over russia.

 

Edit: On the decent into Heathrow and no issues but this is a westbound flight. Im going to do another eastbound and see what happens ill know late tonight or in the morning tomorrow.

[downscc 1,327]

16 hours ago, Pricelss said:

All I did was add the restriction in for BEDEK at 250/14000. When i landed at LAX the yesterday i did the same for the SADDE8. 250/11000 and it dumped them. Could it be the edits before TOD causing the dump?

Do I understand correctly that you are editing the LEGs pages by adding speed and/or altitude constraints before TOD?  This is not unusual, and I do the same in many of my sessions. If somehow the ALT button is being pushed then that would cancel the next constraint in the descent, which brings up the question of if you have a key command assigned in the PMDG Options for MCP ALT Push?

The next thing I'd like to rule out is the possibility of a corrupted panel state file.  Explain how you start your sessions, do you load a scenario that you previously saved or are you starting from the default start with engines running?  Do you have the STARTUP STATE field on the PMDG SETUP page set to a value or is it the default blank?

[Pricelss 2]

I dont push the button and too m knowledge theres no ke command. As far as start up I use the defualt Start up and then start the APU and cut the engines. Then thats it. 

[downscc 1,327]

22 minutes ago, Pricelss said:

I dont push the button and too m knowledge theres no ke command. As far as start up I use the defualt Start up and then start the APU and cut the engines. Then thats it. 

You enter 250/14000 at BEDEK or 250/1100 at SADDE before TOD and then what happens after you press EXEC?  You implied that the vertical path disappears but it would help me visualize this (since I've never seen this) if you would provide more detail.  You provided a screen shot of LEGs but not after the vertical path disappeared and what about the DESCENT page, what happens to your descent speed and next constraint values?  Do the changes happen as soon as you press the EXEC to accept the entry of the constraints?  Does the TOD disappear?

[Pricelss 2]

The Desc path didnt dump until after TOD. All the changes i made were before TOD. I pressed EXEC and it was fine then i went to DESC now and it dumped. TOD stayed in place as the constraint wasnt that far off from where I was calculated to be at.