FMC is going crazy with ETA numbers

[3-2-1-Now 126]

How can scenery interfere with the FMC computations? I'd expect more than a slight error in ToD calculation - more like CTDs from bad memory writes!

 

The algorithms are going a bit nuts, that's all (e.g. rounding errors). I can get some very strange numbers if I do things right! e.g. 2147483648 hours to destination, or 546231 lbs of fuel at DEST.

 

Best regards,

Robin.

[cast65 0]

Same problem here with spinning time.

[gatorbait 0]

I reported this problem sometime back and had no responses that helped. But, I know how to cure the problem when it occurs. In my case this occurs when I'm at the gate programming the FMC, specifically when I insert the cruise altitude. If I insert the OAT temp before pushing the EXEC button (which lights up right after you put in your selected cruise altitude) then the spinning starts. Every once in awhile it happens even if I select EXEC immediatly after inserting the ALT. Then I just change OAT to something radically different than the actual temp and then immeditely switch back and insert the true OAT. And, the spining stops. So, in conclusion i believe it has something to do with some glitch with OAT and programming the FMC.

[ukflight 11]

http://forum.avsim.net/topic/366054-du-and-progress-page-times/#entry2327059

[simbio 56]

Is it possible that for the next SP after the 777 this could be checked, I try to CLR any fault entry on ISA but sometime it doesn't stop to getting crazy.

Thank you

[Tabs 2,790]

Is it possible that for the next SP after the 777 this could be checked, I try to CLR any fault entry on ISA but sometime it doesn't stop to getting crazy.

Thank you

 

We still haven't tracked down the precise cause in the code, but I know that once it starts doing it you can't stop it until the sim is restarted. The ISA or T/C OAT entry you make must be in range (usually this means somewhere in the general vicinity of -56C for the temp - the most common way to trigger it is by putting a positive temp in like 56C) or it'll do this. This is something somewhere in the depths of the VNAV path solver - I'm going to make sure we look at it for SP2.

[simbio 56]

We still haven't tracked down the precise cause in the code, but I know that once it starts doing it you can't stop it until the sim is restarted. The ISA or T/C OAT entry you make must be in range (usually this means somewhere in the general vicinity of -56C for the temp - the most common way to trigger it is by putting a positive temp in like 56C) or it'll do this. This is something somewhere in the depths of the VNAV path solver - I'm going to make sure we look at it for SP2.

Thank's and good hunting.