FMC not showing then not showing Speed & Altitude in FMC

[nbl1936 0]

I have just run into this issue.  I loaded a flight plan, prepared via SimFlight, into the PMDG 777-300.  I went through all the necessary steps in the FMC regarding the INT, SID/STAR, TO speeds, Approach speeds, etc.  I hit ACTIVATE/EXECUTE as necessary.  I did all the same steps as I have done before with no issues.

This time, when I look at the legs page(s), the airspeed/altitude shows, then flashes to "---/------" then flashes to the airspeed/altitude, then back to the dashes and stays there.  I tried loading all into ROUTE 2, but that did not make any difference.  I can't figure out what caused the issue as it has not happened to me before.

One other thing I noticed was that parts of the legs in the moving maps section of the cockpit (all stock PMDG items) were flashing in 'coordination' with the FMC legs page.

Anyone have any suggestions?  I have a feeling I am forgetting something, but not sure what it might be.

Thanks.

Dave Robinette

NBL1936

[Mike777 163]

3 hours ago, nbl1936 said:

I have just run into this issue.  I loaded a flight plan, prepared via SimFlight, into the PMDG 777-300.  I went through all the necessary steps in the FMC regarding the INT, SID/STAR, TO speeds, Approach speeds, etc.  I hit ACTIVATE/EXECUTE as necessary.  I did all the same steps as I have done before with no issues.

This time, when I look at the legs page(s), the airspeed/altitude shows, then flashes to "---/------" then flashes to the airspeed/altitude, then back to the dashes and stays there.  I tried loading all into ROUTE 2, but that did not make any difference.  I can't figure out what caused the issue as it has not happened to me before.

Hi Dave,

What happens if you enter the same flight plan manually?  Have you used SimFlight (with which I am not familiar) before to enter plans?

Mike

[downscc 1,327]

4 hours ago, nbl1936 said:

This time, when I look at the legs page(s), the airspeed/altitude shows, then flashes to "---/------" then flashes to the airspeed/altitude, then back to the dashes and stays there. 

I suspect something in the departure route is preventing the FMS from completing the path predictions. I recommend that you include the route information in your problem description, it is pretty hard to guess at what might be the problem not knowing the route.

[nbl1936 0]

Sorry...should have said SimBrief.  The route was: BSTER2 VALLY WOLFO AR18 ETECK M202 UKOKA M202 KINER 41N060W 44N050W 48N040W 51N030W 51N020W DINIM ELSOX EVRIN UL607 NUMPO UP2 BEDEK OCK2F

I selected the correct SID/STAR from the FMC, and used the proper runways for each 26L for KMIA and 27R for EGLL.  

 

Thanks

 

Dave Robinette 

NBL1936

[nbl1936 0]

Here is a link to a video I just shot, showing what is happening.

https://photos.app.goo.gl/0jN5YioppIgv1Uvr1

 

Dave Robinette 

NBL1936

[nbl1936 0]

And, knowing full well there would not be enough fuel to do it, I tried the same route, with the same SID/STAR in the 737NGX.  No issues at all - except for the insufficient fuel warning.  It must be something I am missing with the 777 but I have no idea what it is.

Dave Robinette

NBL1936

[Mike777 163]

2 hours ago, nbl1936 said:

Sorry...should have said SimBrief.  The route was: BSTER2 VALLY WOLFO AR18 ETECK M202 UKOKA M202 KINER 41N060W 44N050W 48N040W 51N030W 51N020W DINIM ELSOX EVRIN UL607 NUMPO UP2 BEDEK OCK2F

I selected the correct SID/STAR from the FMC, and used the proper runways for each 26L for KMIA and 27R for EGLL.  

Hate to ask stupid questions, but, given that the flight plan on the ND is not magenta,

Are the ADIRUs aligned?  Is the performance data active?  Is the cg entered and trim showing?

Mike

[spesimen 135]

most of the times i see people asking about this it's related to hard speed restrictions in the STAR which are not compatible with the commanded vnav descent speed..  under certain circumstances if your weight is just right, or your cost index a bit high, you can get a situation where it can't make the altitudes and slow down fast enough even with braking etc.. 

i don't have the -300 so i can't test your exact speeds and weights but in that particular star you might want to look, there is a hard limit of 220 at ock, and my legs calculate 250/9396 at the 250knot speed limit point before it (D272L). if i just use standard econ descent it is showing 302 knots at 11000 feet at the point just before that (NIGIT)... that's a lot of speed to lose in 15nm !!  but it calculates for me, so i'm guessing it's doable with brakes on the -200...in your case that speed limit point would be the place i'd look first for incompatibility with your selected descent.

i'd suggest trying a lower cost index, or setting your vnav descent speed to a specific value like maybe 20 or 30 knots less than what the econ is suggesting or even go as low as 280 knots and see if that clears it up for you..

(another fast way to test if this is your problem, is check if the leg calculations are fine before the moment you select the STAR!)

cheers,-andy crosby

 

[pcubine 143]

13 hours ago, nbl1936 said:

I have just run into this issue.

I am curios. What was the cost index you were using? What did the FMC show on the ECON DES page for speed?

[downscc 1,327]

18 hours ago, nbl1936 said:

BSTER2 VALLY WOLFO AR18 ETECK M202 UKOKA M202 KINER 41N060W 44N050W 48N040W 51N030W 51N020W DINIM ELSOX EVRIN UL607 NUMPO UP2 BEDEK OCK2F

I bet you are selecting the EGLL ILS27R with OCK transition.  That is a known bug.  That transition causes the 777 FMC to loose path predictions.  The solution is to select the ILS without the transition and make the turn from downwind to final manually or using the MCP.

[Nyxx 6,993]

On 12/17/2017 at 8:30 PM, downscc said:

I bet you are selecting the EGLL ILS27R with OCK transition.  That is a known bug.  That transition causes the 777 FMC to loose path predictions.  The solution is to select the ILS without the transition and make the turn from downwind to final manually or using the MCP.

I've just wasted 3 hours of my life because the 777 does not liking OCK,

Thanks!

If PMDG knows this Bugs after a year way has it not been fixed and also would it not be a good idea to have a stick with a bug list like this its not like EGLL is a little out of the way airport. I Sat at LEMD for 3 hours trying to work out way my flight speeds etc disappear for 3 hours. I don't even know why a google search would find anything I don't see any know bug list at the top of this forum, do you not think it would be a good idea than you can say "read the sticky about known bugs first!".

No just waste countless hours!

(Not have a go at you Dan, I just find it amazing that PMDG just don't bother even having a known bug list.)

Right I will go do my LEMD-EGLL for the 6-7 time and this time I now know not to enter OCK!!!

 

 

Edited December 27, 2018 by Nyxx

[scandinavian13 5,192]

1 hour ago, Nyxx said:

I've just wasted 3 hours of my life because the 777 does not liking OCK,

Thanks!

If PMDG knows this Bugs after a year way has it not been fixed and also would it not be a good idea to have a stick with a bug list like this its not like EGLL is a little out of the way airport. I Sat at LEMD for 3 hours trying to work out way my flight speeds etc disappear for 3 hours. I don't even know why a google search would find anything I don't see any know bug list at the top of this forum, do you not think it would be a good idea than you can say "read the sticky about known bugs first!".

No just waste countless hours!

(Not have a go at you Dan, I just find it amazing that PMDG just don't bother even having a known bug list.)

Right I will go do my LEMD-EGLL for the 6-7 time and this time I now know not to enter OCK!!!

How is losing path predictions from, what, 7000 to the ground a waste of 3 hours of your life? If you're planning for a severe clear approach to an airport and the weather suddenly gets terrible and you have to fly an ILS instead of a visual, is that a waste of your life?

The 777 has all kinds of different AP modes that could easily tackle this. Is the vert path drop a bug? Yeah, absolutely. Is it frustrating? Sure. Does it make the sim CTD? No. That in mind, I would say that the post is perhaps a bit hyperbolic. I don't blame you for being a bit frustrated, but VNAV not working for the last 5 min of a flight, in a segment of flight you likely really don't have a huge need (or want) for VNAV anyway, isn't exactly something I would consider a huge loss.

Glance at a chart, kick the AP into FL CH or VS, and bring the plane in. It's about 5 min of an alternate mode (heck, I flew the OCK transition in the 747 this morning and chose to use VS anyway, just to make the speed adjustments while descending easier).

What do you mean by "known bug list?" We absolutely have a bug list, which we manage internally. I can't think of anyone who has a public list for what it seems you're asking for.

[Nyxx 6,993]

Here we go,

The point is if knowing that one of the biggest airports in the world does not work with OCK set as a Trans in the 777 that it might be nice to know. But ofc you know, so it’s pointless.

I entered the STAR as I had to wait a huge amount of time for GSX to load 550 pax. To then see the Legs page go to all dashed out, I had no idea why. Why would I? I was going to set up a 2nd route with no STAR but did not get that far because How did I know OCK would throw the Legs page out?

Frustrating....yes even more so when I reloaded the flight with the NG and -8 and then entered the full flight plan again only to see everything is fine to then go back to the 777 and see the Legs page again go to all dashed out.

hyperbolic, Really. I guess you think am just being...(let's use a word very few people do) "Truculent"

Am doing the flight now I just entered OCK as a fix and course etc from with distance.

But you will never see from a customers POV that knowing OCK is a bug with the 777 might be worth letting is know about in a sticky or in any other way you might feel would be helpful. Just what other ones don’t work in the 777?

But it seems your POV implies is it’s all my fault for entering a STAR before atc gave it to be even though looking at EGLL on flight aware was showing 27R and OCK would be the right trans.

Never mind you will just argue black is white rather than say “yes it might be an idea to point out trans/STARs etc that make this happen”

 

BTW the point is there is a bug and as Dan points out its with OCK and the 777, that's the point and how to deal with it is another matter. I did not need 2 paragraphs on how you deal with it, I can do that myself thank you, but since I did not know what was wrong I did not know what i was deal with. The one point I agree with it was frustrating, very. But you just glossed over that in "how I would deal with it and how I should deal with it."

 

Edited December 27, 2018 by Nyxx

[Ephedrin 418]

Complaining about loss of time fiddling with a not perfectly working FMS but using GSX loading 550 pax sounds... ironic. 

I wouldn‘t want to see all those threads about „why is that bug not fixed yet“ if there was a public bug list. I saw a list like that at another dev‘s forum a year ago and it was a big mess, really. Just like the addon itself. 

I had a nice talk with an A330 captain recently and he told me how they had to do a whole flight in selected mode as the FMS simply refused to calculate that magenta (or green in airbus) magic. After he returned to Zürich the airplane was taken into maintenance and the next day it was back in the air.. there are pilots for a reason.

Edited December 27, 2018 by Ephedrin

[scandinavian13 5,192]

8 hours ago, Nyxx said:

Never mind you will just argue black is white rather than say “yes it might be an idea to point out trans/STARs etc that make this happen”

Don't put words into my mouth.

I was simply saying that your assertion that it was a waste of time seemed a bit extreme. It's a bug. I acknowledged this. All the same, the bug is not a showstopper that causes the entire flight to be a wash because VNAV doesn't work for the final five minutes. If VNAV were the only mode, fine, but it's not, and most people aren't even in that mode anyway.

So...does it need to be fixed? Absolutely.

Is getting upset that there is a bug unreasonable? No. It merits a bit of irritation, as I actually did state earlier.

Is calling the entire flight a waste because of this bug reasonable? I would argue yes.

8 hours ago, Nyxx said:

BTW the point is there is a bug and as Dan points out its with OCK and the 777, that's the point and how to deal with it is another matter. I did not need 2 paragraphs on how you deal with it, I can do that myself thank you, but since I did not know what was wrong I did not know what i was deal with. The one point I agree with it was frustrating, very. But you just glossed over that in "how I would deal with it and how I should deal with it."

Even real aircraft have this kind of failure. I stated clearly - as I have in this post - that the bug exists, and is frustrating. To be blunt, if you consider the entire flight a waste because VNAV dropped out, perhaps you did need the additional detail on how to side-step the issue. If you don't want pushback, then a little moderation and perspective goes a long way. If it were a CTD on approach (like the original 777 had with VHHH, or VHHX, I forget which), then yeah, the flight was a complete waste, and a post with some vitriol would be merited (especially if it were across the entire Pacific, or Siberia), but this was the semi-failure of an AP mode. Frustrating, sure, but a wasted flight? Hardly.

Bugs are bugs, and they affect people. I get it. They need to be fixed. I'll be the first to admit that. A little perspective on the type of bug, though, is warranted.