FMC NAV RAD not working properly

[Guest NICO DHONDT]

Hello,After making a few flights, the VOR tuning of the FMC becomesinaccurate. That is, picking the wrong ones and when I try amanual entry like 117.55, I get 117.00. However, the FMC carries out a normal LNAV and VNAV. I align the IRS L, C and R every time I start a flight. I alsomake a purge at the pos. init page.How can this annoying problem be solved.?Regards,Nico

[Guest D17S]

The FMC pretty much has a mind of it's own when it comes to deciding which VOR to tune. As you know, those auto-tuned VORs are providing updated PP data to the FMC. You really can't outguess the FMC about which VOR is the best one to use at any particular moment. It's huge calculation that is constantly going on in the FMC's little brain. Can you give a little more info about what you're seeing?

[Guest NICO DHONDT]

If the FMC can't find the right VOR, it is obvious that I type itinto the scratchpad. I can type the name such as LON (for London),which it founds immediatly, or I can type the numbers myself.But when I do the latter the following happens. The frequency for London is 113.60 and when I type it into the scratcpad and upselectit, I get 113.00, which, of course does't work. Also when this startsto happen, every input whith a decimal is not accepted by the FMC.For example, when entering the reserve fuel into the scratchpad, theFMC do not accepts the numbers after the decimal. When I type 2,5 itbecomes 2.0 after upselecting.Also, when tuning to LON VOR, is it normal that the FMC only gives113.60? Schouldn't it also be displaying LON next to the numbers?I notice that when only 113.60 is displayed on the FMC it is impossible the see a radial. Also, the VOR in particular is not displayed in green on de ND.!Hope all this gets you any further.Regards,Nico

[Guest D17S]

The decimal thing and 're-jiggering the numbers' sounds a little buggy. A re-install might be something to try there. There will be times when the FMC only wants one VOR station. It can use VOR/DME from the same VOR station. It will use the VOR radial and the DME distance from that same VOR station. In that case, it's not that the FMC can't find a second station, the FMC doesn't want one. I don't think we can override the FMC's selection of VOR stations that it has auto-tuned for FMC update purposes. If this is the cases, it makes sense that you will not be getting the green line from your manually tuned VOR station to the PP triangle on the ND. This because the FMC is not using the manually tuned VOR for FMC PP updating. That part might make sense. But we're just thinking reasonably without 'operational certainty'. Still though, we can certainly manually tune VORs for 'normal', old fashioned navagatin'.Do you have a favorite route into or out of London? If so, post the flight plan string and I'll fly it to see what my install does with it.

[Guest NICO DHONDT]

Hello,I've done several re-installs. Sometimes it helps, sometimes not.If it helps, the first flights might be ok, then the FMC begins its stubby behaviour. It is certainly not route specific, but if you want to try the route from Brussels Belgium to London..go ahead!EBBR - EGLLROUTE : HELEN L179 SASKI PELIX L608 LOGANSTAR : HELENSID : LAMFL 180Note :Normally I always start a flight with the engines running.Well, I created a cold and dark at a certain airport and saved it.Then I started with that particular file and all worked well.Could this be the solution?Regards,Nico

[emvaos 13]

Check your regional settings. Windows get confused in some cases between the dot and the comma (. as opposed to ,).Vangelis ===================================== E. M. Vaos Precision Manuals Development Group www.precisionmanuals.com=====================================

[Qavion 19]

"Also, when tuning to LON VOR, is it normal that the FMC only gives113.60? Schouldn't it also be displaying LON next to the numbers?"It depends on whether the station is in range or not. The VOR receivers decode the received VOR morse ident audio and send this information to the instruments.Cheers.Q>

[Guest NICO DHONDT]

Why can it be the regional settings? I must klick on the numbers andletters of the FMC to type info into the scratchpad.Anyway, here in Belgium we use azerty in stead of querty. Could this be of any importance to you?Also, when the FMC's VOR-tuning starts to fail, it comes togetherwith the dot/comma case.Regards,Nico.

[Guest D17S]

But just for fun, check out Control Panel > Regional and Language Options > and then the Regional Options tab. It looks like the

[michelmvd 0]

Hi Nico,>Also, when tuning to LON VOR, is it normal that the FMC only>gives>113.60? Schouldn't it also be displaying LON next to the>numbers?>I notice that when only 113.60 is displayed on the FMC it is >impossible the see a radial. Also, the VOR in particular is>not >displayed in green on de ND.!As long a VOR station is not in range or firmly indentified only the figures (113.60)are visual in the ND, once the station is positively identified the figures are changing into the VOR ID (LON). Therefore you don't have to listing to the morsecode anymore ;)B. rgdsMichel

[Guest D17S]

Test Flight Update:Well, I took a run in at EGLL. Approaching from the north east, the FMC was auto-tuning away with no problem. The FMC seemed to be happy as a clam with its various selections of 2 auto-tuned VOR stations and was updating away in its preferred DME/DME mode. Once I was within 50 miles of London I started to play with manually tuning VOR freqs. Ok. Let

[Qavion 19]

The real FMC can chose to ignore two bogus, manually tuned stations, Sam. It doesn't have to use the stations you have chosen as long as there are two other DME stations within range with suitable geometry. Each DME interrogator(transmitter/receiver) can tune five different stations at the same time... and there are two DME interrogators on the 744. Manual tuning only has the potential to use up/block 2 out of a total of 10 different DME channels.Cheers.Ian R>

[Guest D17S]

So, at a moment in time, the FMC finds 2 VOR/DMEs that is likes and is using just the DME data from these 2 for PP update. Life is good. At this moment, I re-tune both VORs off frequency. The FMC still has these 2 like-able VOR/DMEs shacks in range. It will still automatically tune the airplane's DME interrogators - autonomously - to these de-tuned VOR's paired DME frequency and continue DME/DME updating uninterrupted. VOR and DME are two entirely separate radio systems. They just generally live in the same house. Why not treat them that way? Heck, why not? I like it.In the previous scenario, update should have stayed in DME/DME when I detuned the first VOR. I also immediately detuned the second VOR and the IRU stopped radio updating all together. The model

[Qavion 19]

"Bug alert?"PMDG already know about this, Sam. Reprogramming the entire navradio updating system is another matter."(Who's this Ian guy, Q? Should we send help!?)"Sounds like an imposter... my arch enemy, called "slipofthetongue" :)Cheers.Q>

[Guest NICO DHONDT]

Hi Sam,Thanks for doing the flight.I thouhgt I had figured it out by starting from a cold and dark scenario, aligning the IRS etc. In the beginning all seemed to workwel. But when I connected to a network to fly online it becameimpossible to aligne the IRS system. When I upselected the GPS pos.to downselect it into the requested IRS position, the FMC repliedwith ILLEGAL ENTRY. When I had the IRS aligned before the connection to the network it worked wel. But when I connected Isaw the green VOR -pointers on the ND disappear. A manual entrywasn't possible (e.g. : 116.30 becomes 116.00). Only an entry likeLON will tune, and still without the LON notification on the ND,although the LONDON vor is in range.So the decimal bug was very much alive and so became the problemof the online connection.I decided to make a flight with the PMDG 737 and there was thedecimal bug again. The 737 displayed the tuned VOR correct, withinstant notification of the name (e.g. LON), green VOR pointer and with the chosen radial.But here we had the decimal bug again.The decimal problem does not always occur. So I believe that therecan be no problem with the regional settings. I decided to delete everything related with flightsim. on the pcand start again. This wil take some time between my regular workand family bussiness. I will inform you next week if this completereinstall is better or not.Regards,Nico