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Guest Stefan Bergert

PMDG-menu GPS checkbox greyed out

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Hi everybody!Why is the "aircraft is GPS fitted" (or text similar) tickbox always greyed out so you can't check/uncheck it? Tried it with the 737-800 and the 747. I want to fly my 747 without GPS-updating...Any ideas?Best regards,Stefan

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Hi Stefan,the PMDG 744 is GPS equipped by default, as are most new aircraft being introduced into service recently in real life.But if u really want to fly without the GPS updating your FMCs position, go to the PROG page, select POS REF prompt, and then again select INHIBIT GPS NAV, and you will see that the FMC will revert to updating the position using a mix of DME/DME or DME/VOR or an average of the 3 IRUs position if out of conventional VHF navaid range.Regards,Bjorn

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Hi Bjorn,thanks for the advice - that's how I did it already.I was asking because there is this checkbox in the PMDG-menu but it can't be checked/unchecked obviously, that's what I was wondering about... maybe it was for a future update.Thanks for the hint,Stefan

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Hi Andy!What is it for? Downloaded and opened your file but I don't know what that program does or how to use it.Stefan

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It enables any greyed out button or check box you put your mouse over. All you have to do is run it in the background. You can tinker with the PMDG settings with the program.

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That has no effect. The PMDG 744 only uses the FS GPS position. It won't even allow you to enter a position that's not the same as the GPS position. Is this the way the real plane behaves?

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> It won't even allow you to enter a position that's not the same as > the GPS positionAre you sure of that? I think it's possible to do by entering a ref airport in the pos init page. I do know that if the aircraft has moved since the last IRS alignment you need to RE-ENTER the co-ordinates a second time in the SET IRS POS line to be sure that you are entering the correct value.Inhibiting the GPS updating is possible, at which point your navigation accuracy will start to *slowly* degrade over time if you;re away fomr nav rad stations. Next time you're crossing the pond, inhbit GPS updating and select the POS mode on the ND as you fly away fomr land. By the halfway point you'll see a gradual spread or drift in the positioning of the three IRS position asterisks. (nicknamed 'dancing girls' because they jitter around a bit!) As you approach land and start to autotune the available nav rad stations, the FMC will do some triangulation and update the position of the IRS units, at which point the 'dancing girls' will tidy up their act and get back in formation. Fun to watch.Page 55 chapter 12 of the manual if you want to read more.

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Thanks for the replies to everyone - I'll try your tool, Andy, thx for that.Just one little addition on the last topic: I think the dancing girls don't move back into position again since they represent the 3 IRS'and the IRS' can't be corrected by NAV (VOR,DME,LOC etc) or GPS, only the FMC-position can be updated and is updated when NAVAIDS come in range again.So the 3 IRS stars should show the same displacement, the aircraft-symbol would move when NAVAIDS come in range. Since the aircraft -symbol always stays where it is, the map will move relative to the aircraft-symbol.Just my 2 cents,Stefan

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