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breakinghbts

A/P disconnect during ILS

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Hopefully there is a quick answer to why this keeps happening, but Often, tho not always, and at varying airports world wide, i find that once i get below the 200' callout, my A/P will disconnect, but not the A/T. The plane always immediatly rocks side to side, and for the most part I'm able to save the approach for a smoothish landing. I thought it was an AI issue, TCAS or something, so I tried a flight with zero AI. Still happened. It happens most on HNL's 8L. But the more and more i fly, the more its happening to me at other airports, last night @ PDX for example. I have the Vref set, and selected, usually i fly VNAV until nearing final, i'll select the APP button, and after the turn towards final the autoland kicks in. Flaps 30, i almost always do flaps 30 landing. Gear down. If I'm missing something that could help solve this, let me know. Any clues as to what i may be doing wrong, or neglecting to pay attention to are welcome, as I've found these issues are usually due to "pilot error".

 

So again, thanks in advance for any advice!

 

-Tony@PVD

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Does the 744 line up properly with the runway? If you notice any misalignment, or map integrity on the ND is lost, you should run the FSX registry repair tool (one of them ...).

 

Did you choose an ILS approach in the CDU? Or is the programmed approach of a different type?

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Ok, i should have mentioned this is in FS9. Sorry i forgot about that. But the ILS is chosen from the CDU. A/C lines up perfectly. There is no sign of anything wrong with the approach until I've flown past the "minimums" callout. Is there an FS9 registry tool? I've read about that fixing misaligned approaches, but thats not my problem here. the weird thing is, it doesn't always happen, and i've been trying to troubleshoot this for weeks, so i've taken notes on exactly what i do each time, to see if something is wrong. At one point I had thought it was because i 'reset' the altimeter at too low an altitude. That turned out to be a non issue. At this point, i'm pretty lost.

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Forget about the registry entry; that issue is specific to FSX.

 

Baro altimeter doesn't affect ILS landings; those are based on radio signals - strictly "AGL stuff".

 

A bit insecure myself, now: Any PMDG options that could affect ILS landings? Maybe you check your settings there, just to make sure ...

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Its been awhile since I've gone thru the PMDG settings, I'm at work now, but maybe when i get home, i'll take out the manual, and go thru the settings one by one and see if i can find something. It drives me nuts, because it ruins what would otherwise be perfectly smooth landings.Thanks for your help, wish me luck!

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Do you have the ILS course set correctly together with the frequency in the NAV RAD page, and does the course agree with the FMC nav database?

 

If your "couse" settings disagree you usually get a FMC warning.

 

This often happens if you update the navdata, but are using an old airport scenery or vice versa. If the runway course has changed your two course settings will be different.

 

Peter

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Do you get the correct annunciation: LAND 2/LAND 3? Or is it NO AUTOLAND?

 

That rocking side to side is a strange issue, too.

 

You said already lineup on final is o.k., so the distance to touchdown when intercepting the LOC can't be an issue, right?

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Ok, so I havent had time to go thru the PMDG settings yet, but i can respond to the other questions. I have not checked the course settings, in fact, honestly unless there is an issue of some sort, i rarely check the NAVRAD page, however, if like u say it should give me some kind of warning, there definitely hasnt been anything of the sort pop up on the FMC. I do however use plenty of addon scenery, so im going to keep an eye on this the next time i hop in the sim.

 

As far as the autoland, i do get land 3. I usually intercept ILS between 12-8miles out, depending on the approach procedure to the rwy. It does line up perfecty, intercepts the G/S and decends perfectly...until after 'minimums'. In fact thinking about it now, could it be a conflict with AS6.5? Something where the a/c thinks i cant see the rwy?

 

Hum, very frustrating. And I have OT all week at work, so itll be a few days before i'm able to hop back in and troubleshoot some more. But i do appreciate all the help, and anymore suggestions certainly are welcome! 

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AS6.5 affecting the landing with turbulence and/or gusts? Could be an issue but it would not reproduce with fair or clear weather theme in FS9 and AS6.5 'off'.

 

Reproducing wake turbulence would be even more difficult. It occurs only rarely and - most likely   ;-)   - would not happen with AI traffic and/or AS6.5 'off'.

 

(Try weather/AI/AS6.5 all 'off' just for troubleshooting.)

 

Just to make sure I got it right: There is no wing rocking when capturing the LOC and lining up with the runway? The rocking occurs only later, after the A/P disconnect and below minimums?

 

Not sure about one specific option myself (does it exist in the 744 FS9 at all?): Is there an ILS approach with a 'LOC only' option? Which means, AFAIK, that the G/S is either unreliable or INOP? (Well, there should be no AUTOLAND 3 message in that case, should there?)

 

Maybe you could upload a screenshot if this happens again? PFD/FMA clearly visible would be important in that case.

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With AS6.5 I was thinking it was a visibility issue because it happens past the 'minimums' callout. The glideslop option doesn't seem to apply, as it descends just fine from capture alt. I am in the middle of several unplanned doubles are work, so the earliest I'l get some sim time is thu. But if i cant seem to find anything in the PMDG options to fix it, or if the course heading isnt the issue (which im doubting, but ill try anything), i will pause the second the A/P disconnects, and take a screen shot. Maybe that will help narrow it down, Thanks Again!

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No need to pause, just hit the hotkey for the screenshot function (not sure whether it's the same as in FSX: 'V').

 

You may hit it a couple of times during the landing at different stages (as some fancy camera would do automatically) and later on select the one(s) which display what's important.

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Wake Turbulence effects in ActiveSky.

 

for some reason, aircraft that are parked and sitting on the ground produce massive amounts of wake turbulence that drifts downwind, especially if using "Online" multiplayer traffic (vatsim for instance) rather than true AI. (I think some AI do it still anyway).

 

Turn off Wake Turbulence (or at least way way down to like 1 pixel from the left)

 

If the air 'spins' the aircraft hard enough, it will disconnect the autopilot as it is physically unable to maintain bank angle within limits.

 

I'v had this happen on reinstalling active sky a couple of times on Vatsim, and a full deflection of stick left (for instance) was unable to arrest the right roll, Then as you pass 'through' the wake, it will suddenly 'snap' to a left roll. Autopilot will disconnect if it is on, and flying manual controls you are unable to stop the roll with even full deflection of yoke.

 

50% Wake turbulence effect in Activesky is perhaps hundreds of times too strong compared to real life, enough to push a 747-400 into a 90° bank on short finals passing 200ft if there is an aircraft holding short of the runway.

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I tried 5 or 6 different landings over the weekend, no AI. Didn't get a single A/P disconnect. Then i read hopskips's post, and that makes the most sense. I'm going to have to turn off or down the wake effects. Hopefully my days of fudged landings are over!

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Great advice!  I'll stash that away with everything else I have to learn.  One extra piece of advice though:  make sure your cellphone is off during landing.  :lol:

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