nbl1936

FMC not showing then not showing Speed & Altitude in FMC

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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

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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

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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.

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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

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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

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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

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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

 

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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?

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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.

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