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Problems with 757 and ILS CAT III Approach

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Guys,I've attempted an ILS CAT III approach a couple of times,with the same results both times - the airplane lands tothe right of the runway! In both instances, the airplanehas begun drifting to the right (I've verified that the LOCmarker on my instruments was in fact deflecting to the left)starting at about 2000' and getting progressively worse downto the ground. One runway was 8R at KATL, the other 22L at KORD. (Anotherproblem, which may be Fly!-related, is that I wasn't ableto obtain a G/S with 22L at KORD - the G/S marker stayedpegged at the bottom the entire time...??)I've had a lot of experience flying ILS approaches withthe PMDG 777 (and other planes), and never had issues like this...Please tell me I'm doing something wrong!(If need be, I'll fly one of the approaches again, andsnap some screen shots)- Bill Ruppel

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Guest

I do not have a definitive answer to your problem, but I have done some sucessful auto lands, and have had the prolem you described a couple of times too. Just so that we are on the same page, I assume that you had all three autopilots on, as well as both LOC and APP engagued. 1. During your approaches, did the Land 3 annunciator come on? The time my plane landed to the right of the pavement (runway 16 at LGTS in PMDG's Greek Scenery), I never received the Land 3 confirmation, although the Autopilot tracked the glideslope to the ground without incident, seting me down gently, but in the grass. Normally this light should come on during the final descent to the runway.2. Therefore, it may have something to do with particular airports/runways in Fly!II. Try using one of the outer runways at KATL. I know that 8R is normally used for takeoffs there, but I don't think I have made an autoland at that airport yet, so I can't say that I know it works.3. Try landing on runway 9 at KSAV (Savannah, Georgia). I recently did an autoland on that runway in the 757 and it worked perfectly.Good luck,Andrew

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Yes, I had all three autopilots on, with LOC and APP engaged.And yes, the Land 3 annunciator was lit as well.I'll try runway 9 at KSAV tonight, and let you know how it went.Thanks for the feedback Andrew!- Bill

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Guest tonyc

Also try another plane to make sure that it's not FLY that's the problem. I have had that happen too.tony

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BillI have had the same problem at certain airports. Not sure if this is a FLYII thing or not, Always lands on the money in LAX and SFO but drifts off the right side everytime in SJC.RegardsPaul:-cool

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I've had the same problem. Take a look at my CATIIIc approach post, back a few days. Robert said that I didn't have the localizer tuned in. I had the localizer tuned in on the center pedistal not the main one next to the MCP. I'm sure I had the approach set up properly with all three autopilots with loc and app selected. You can clearly see in the screen shots that it is toward the right.CB

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Well, I tried a couple more approaches at KATL (takeofffrom KATL, circle, land at KATL - didn't bother with FMCat all) and landed ON THE RUNWAY using CATIII each time!Argh! I even tried a crosswind component.I know there's a problem in there somewhere, I just need to figure out the repro case.- Bill

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Hi Bill,During testing I encountered this problem and determined that, for me, it was a Fly2 issue. Please try an ILS landing with another aircraft such as the Hawker. I realize it doesn't have CATIII, but as you have mentioned, things start going wrong before landing.If other aircraft have the same issue than we know it is not a PMDG problem.George

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But, I tried the exact same runway (08R) at KATL thatI had problems with the first time... and didn'thave the same problem! Argh!If I can get a consistent repro case, I will definitelydo as you suggest, and try the Hawker.Thanks, George.- Bill

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Ahhh... didn't catch that Bill, sorry. To clarify, I did not encounter having different results on the same approach and runway during testing. I will do some additional testing at KATL over the weekend and see if I can replicate what you are encountering.George

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Guest

Hi Bill,for me it sounds like a crosswind issue. Did you check the wind indicator in the lower left corner of the EHSI? You can see the direction of the wind with the little arrow and the speed with the number. Just check if you drift to the direction of the wind.You can try to not load any metar and set the wind to 0 knots manually in FlyII. Try to land again under this conditions. If your landing will be okay, you can be pretty sure that it is a crosswind issue (this would be normal anyway).Usually you need check the crosswind table in the manual on page 1-11. Did you ever try to interact and "help" the Land 3 a bit? I don't know about reality, but I could imagine that this is the way the pilots do it. Maybe Robert can jump in here and tell us how he do it ;-)Good luck and happy landingsBest regards

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Yeah, if you take a look at an earlier message of mine... >Well, I tried a couple more approaches at KATL (takeoff >from KATL, circle, land at KATL - didn't bother with FMC >at all) and landed ON THE RUNWAY using CATIII each time! >Argh! I even tried a crosswind component....you can see that I did try a crosswind component - thefunny thing is that I just cannot repro the "drifting tothe right" now! As I also said in that message: >I know there's a problem in there somewhere, I just need >to figure out the repro case.Thanks for the input, Gerhard!- Bill

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Guest

Hi Bill,if I fly under random weather conditions, what I usually do, most of the time my approach with Land 3 is less or more beside the runway if I leave my hands of the flight stick.I thought thats the way it should be. Only whith no or almost no crosswind Land 3 brings me perfect to the centerline without any interaction.Maybe you are right and there is something wrong. Unfortunately I am not a pilot and don't know much about the real thing.Good luck with figuring your repro case.Regards

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About 'helping' the autopilot... I've used three different autopilots in my couple years of flying, all have been placarded 'DO NOT ATTEMPT TO FLY THE AIRPLANE WITH AUTOPILOT ENGAGED.' Perhaps the airliners have systems that allow for pilot intervention? That'd be some bit of programming, because no matter what the pilot does, the a/p (I would think) would still want to go back to it's previous course of action which it apparently thought was correct. But when all else fails, slap the disconnect button and fly the airplane.SP

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Hi Steve,thanks for your help. Good to know such things to make it even more realistic.I like the one you said: "Slap the disconnect button ..." I will try this next time rather than "helping the A/P". This will be even more challenging.Have a good one

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Guest Hagar

Interesting discussion.I have the same experience. As long as I don`t set the wind to zero,the plane touches down beside the runway. So, as long as I have stronger winds, I use the APP only to guide me to the rwy, and as soon as I have a good visual I switch to hand-flying.I am going to experiment with the Max. crooswind/tailwind component,and see if that works out.The Hawker has landed me perfect on the centerline with crosswinds...but still no crosswind compensation on the big jets. The LOC needle is compensating, but the plane does not follow...

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