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Guest jayson2830

Auto land Problems

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I could not find a post on this subject. I have trouble landing all of my 737 Models,600,700,800,or 900.I get the approach set up nicely.Lined up on the localizer and glide slope,both Autopilots set to cmd then the aircraft starts to slow down,the autopilot applies trim to try to stay on the glideslope which it fails to do,then the second cmd light goes out and then I have to disconnect the Autothrottle and put in nose down trim to keep from stalling.Then I have to hand fly it to a landing.(that is if I catch it before it stalls. I saw a few posts about Station loadsand followed those suggestions but to no avail.

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What speed are you setting your MCP to when coming in for landing?I found out that I have to use consistently 10 knots over the Vref suggested by the FMC for a particular flaps setting...Works well for me!Robert

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How long does the a/p stay connected after capturing the g/s ? I had a similar problem which I'm now sure was due to me going to fast and the App mode would disconnect almost as soon as it connected. I'm now much more careful with speed now and it hasn't happended since. Are you intercepting the g/s from below, otherwise your aircraft will skip over the glideslope which is why I think it connects and then quickly disconnects.

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Yes I have been Intercepting the GS from below.Since I sent my orginal post I have doing some experimenting.I have successfuly done two out of three successfuly,by keeping the AS to around 190 knots Until glideslope capture. Then I gradually decrease the speed until I reach FMC landing flap and speed ref settings.Until now I had been reducing to FMC ref speed and flap settings as soon as I captured the glide slope and had both autopilot cmd A and cmd B ind lights on.Shortly after the Aircraft would start to pitch up excessively causing the Aircrafts Air speed to slow and putting it above the glide slope.Then the CMD B light would go out and the Aircraft quickly approaching a Stall condition.It took fast work to disconnect the AP and trim the Aircraft nose dn to get the airspeed back and recapture the glide slope in order to hand fly to a successful landing.(Note as a Commercial and Insrument rated Pilot I have made many Instrument appoaches,so I know the procedures like the back of my hand.)

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Rich,I bow to your superior knowledge then - and hope you get the sim side sorted !

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Dave I hope I didn't leave the wrong impression. I appreciate yours and any one else's suggestions. I was only trying to explain that I know the procedures and I think the problem lies with the PMDG autoland feature.

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Rich,No problem - hope I didn't sound sarcy - it wasn't intended - it is genuinely good to be able to exchange information with people who really know what they're talking about.

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Just a quick question Rich, what type of descent profile are you flying that has you well below G/S on final? I'm not sure what exactly the issue is here (certainly possible there is one) so can you post a screenshot the moment the A/P "B" disconects? [h4]Randy J. Smith[/h4]

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Randy I have been flying vectors and altitudes that ATC assigns. Once I get the loc and gs locked in (app mode). I set speed and flaps according to FMC approach info.I gradually reduce speed and increase flap settings. Up to this point everything is hunky dory.Then things start to happen.As soon as I engage the CMD B autopilot The aircraft starts to pitch up excessively and airspeed delcines (do to the pitch change). This causes the AC to get below the glide slope and at this time CMD B disengages.I have to disengage the AT and manually push the throttles up to try to increase the altitude, and trim down to increase the speed, but by then the aircraft has reached stalling point. I don't know if the pitch change is caused by drag from the flap settings or because the autopilot is trying to get back on the glide slope. Sometimes if I act quickly enough I can salvage a landing . PMDG tech support thought I might have a corrupted file so they let me download a fresh install but that did not fix the problem . The next time I fly I will take a screen shot at the critical moment. (I think I will experiment using a higher air speed and lower flap settings until about three miles out.Also I will wait to that point to engage CMD :(.

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