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BobbyBond2

Autopilot Disengage on Final

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Hello All -Just wanted to make sure I'm not going crazy :-) , does the autopilot disengage on final due to tough Windshears?I was also curious if it would disconnect due to a potential traffic collision from the TCAS. I was on final into KRDU yesterday and winds were nasty, so I couldn't tell if it was windshear, but the autopilot disconnected and my pax went for a roller coaster ride ;-)Thanks!

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Rob,Yes, sudden wind shifts or wake turbulence might disengage the A/P. I would disengage manually before final approach if the above was anticipated.No, the A/P will not disengage due to RA from TCAS.Hope it helps,

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Guest boxjockey99

RobAs stated by Mats yes the autopilot will drop out in very windy conditions although I have yet to see it happen on the -300 I fly in my day job. Even flying through a CB on approach to Venice didn't beat the A/P and it held on all the way through it although I have to admit I had the controls covered the whole time just in case it did finally quit on me! The TCAS isn't connected to the A/P so will not cause the A/P to drop out. This is probably a good thing as we have been having problems with RA's recently in RVSM (Reduced Vertical Separation Minima) airspace where a high performance aircraft like the 737 is climbing at a high rate to 1000ft below another aircraft. The TCAS sees this as a potential collision and issues an RA (Resolution Advisory) even though the MCP is set to 1000ft below the 'target aircraft'. If the TCAS was connected to the A/P we'd end up with many more disconnects than normal. Incidently in order to beat this TCAS problem we simply change mode from LVL CHG or VNAV into V/S and set the Vertical speed to 1000fpm, this seems to sort the problem out as it takes you out of the RA parameters although you still usually get a TA.All the best Kris

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It must be very tough winds for it to drop. Anyways, thanks for all the help and response. Guess I'll have to have a tighter grip on the controls :-) .Regards,

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When you say the A/P kicks out exactly what is it that tells you this information? The reason I ask is because typically it can be-Hardware related = Force Feed Back enabled causing reversion to control wheel steeringSoftware Related = Weather Programs not set correctly causing serious shifts in wind that effects IASPilot error = Sometimes folks mistake the APP light going OUT as A/P disconnect when it is what really happens, so they neglect to look at the PFD's FMA for proper MODE engament at G/S..Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/southparkcartmad.gif[h3]PMDG 747![/h3]Caution! Not a real pilot, but do play one on TV ;-)ASUS KV8 DLX | AMD 3200 64 | 1 GIG PC 3200 DDR | GIGABYTE 5700 ULTRA | ViewSonic VP192b 19" |

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Randy,I guess I have the same problem sometimes, so I just go ahead and answer to your questions based on my experience.I always keep a hand on the controls, not that the A/P can not do the autoland function brightly, but it is wise to do so. No input whatsoever, so point one is out.Software is AS2004.5, and it is configured as by default. But I have noticed, that when exiting FS and AS after a flight that had this issue at landing, AS always shows this last system message at the bottom of it's window: wake turbulence effect completed. Can this be the cause?Ps. APP light out is not recognized as A/P disconnect; there is however an aural warning and A/P 1&2 lights go out.Cheers,

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Randy -I'm using AS2004 4.5, I looked at my options last night and Wake turbulence and Windshear options were checked. I would imagine that was the case, on approach in the RDU there were very nasty winds. Now on AS2004, I've never noticed the "Wake Turbulence effect completed". Now I know this is not a PMDG issue, but does the program simulate Wake Turbulence if no aircraft is in sight? or only when aircraft are around.Thanks!

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Balint & Rob - You are both using AS2004.5 so I would rule out the software related drop out cause by the severe wind shift flaw in FS9 Randy mentioned. If you are seeing CWS P or CWS R in your FMA after the A/P revertion. It is dues to inputs from the controls to the A/C. CAn be avoided by not moving the controls during A/P engage and/or checking your force feedback set-up.Rob, there has to be an aircraft for AS2004.5 to simulate wake turbulence. And seeing you had windsheers checked I would still say, and Kris confirmed, your A/P drop-out was perfectly normal behaviour. You could possibly dampen the turbulence behaviour for FS by decreasing the turbulence scalar setting in fs9.cfg. I have seen others confirm that the default turbulence for FS9 is way too severe. I can't remember the variable name now from the top of my head. BUt hopefully someone who remembers it can chime in here. I think the recommended decrease was from 1.0 to 0.2.Hope it helps,

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In the FS9.CFG TurbulenceScale=1.000000I believe this is default since I've never changed it. I'm not sure what to change it to though to make things less severe. I was on a dual radio ILS final to KMSP, at about 300 AGL the airplane suddenly nosed down severely (with an a drop in airspeed as well) and I was unable to recover.I blamed this on myself because I should have adjusted my approach speed due to windy conditions.Not being a real pilot, I can't say for sure. But the wind changes in FS9 sometimes seem unrealistic. Like a 85 knot headwind suddenly becoming a 50 knot tailwind? I woudn't want to be sipping coffee in coach at that moment!!!

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