retard in "white" autopilot mode

[Guest meirumeiru]

ok, tried that... I did touch down with 142, 142 selected and, it remained in the "thrust" mode... LW was correct... everything ok... the spoilers deployed, and it still didn't retard ... but, what I saw now is, that the "magenta circle" on the speed-bar is at 180 ... so, for some reason, the FMS thinks, that this is the best speed for the current situation... don't ask me why... and don't ask me, why the ATS is doing what the FMS is telling, if those systems have no relation with each other (as some sayed)...

[Paul_Smith 92]

I don't see the green box. Have you armed the spoilers etc.?@David Harrision: While your pictures are very pretty, they are quite a bit larger then forum rules allow for.

[FLEX1978 373]

I don't see the green box. Have you armed the spoilers etc.?@David Harrision: While your pictures are very pretty, they are quite a bit larger then forum rules allow for.

Yeah David, I was thinking the same thing, I thought you were posting sceenshots :) Nice shots! I think they are too big :) Paul, the whole thing just looks wrong after flying many approaches myself, as you said it looks like he is flying into the ground rather then landing. Wish I had access to my sim so I could confirm this. If your at home maybe you could get screenshots of a correct managed/selected approach?

[Guest meirumeiru]

I don't see the green box. Have you armed the spoilers etc.?@David Harrision: While your pictures are very pretty, they are quite a bit larger then forum rules allow for.

You're right... I don't have the green box... but I don't remember, if I had it in the FMS mode... the spoilers are armed (alltough, is that needed on landing? ... for touch and go for example?) and I set the auto break to someting between min and max... flaps 35 or 50, gear out... I don't know what's missing? ... lights? are on... correctly trimmed flying in without problems... ILS activated and... still no green box... I agree, that something must be wrong... but I've no idea what it could be...next thing I try is to fly a very short flight... maybe I'll be able to remark something... or... isn't it enough to disable the autopilot, should I also select an altitued of 0 first? ...

[FLEX1978 373]

You're right... I don't have the green box... but I don't remember, if I had it in the FMS mode... the spoilers are armed (alltough, is that needed on landing? ... for touch and go for example?) and I set the auto break to someting between min and max... flaps 35 or 50, gear out... I don't know what's missing? ... lights? are on... correctly trimmed flying in without problems... ILS activated and... still no green box... I agree, that something must be wrong... but I've no idea what it could be...next thing I try is to fly a very short flight... maybe I'll be able to remark something... or... isn't it enough to disable the autopilot, should I also select an altitued of 0 first? ...

No, altitude should be set to Go-Around altitude after G/S intercept

[Guest meirumeiru]

No, altitude should be set to Go-Around altitude after G/S intercept

That's what I thought ... well, I tryed to fly from WMKK to WMSA (very short flight) ... and, I was able to get the green bar on final... and... this was after pushing the auto-land button, but then I disabled it again and flew it manually... so, I can't say why it worked this time, because I did to many things, but it seems, that the retarding works, when I'm able to get this green bar... but I don't know why I don't get it always... I don't think, that I did something different (of course, I did, since otherwise it would behave the same way round... it's just software, I know that)... this time I also had the first officer anouncing "glide slope is alive" and "localizer is alive" ... I never heart that before...well, it remains interesting... I'll try to figure out, what makes this green bar showing up and why sometimes the systems seems to hang on the 180s in the middle of the descend (this is the descend speed, because otherwise it would be 250 below 10'000 feets).

[ahinterl 1]

Thats what the manual says about the retard autothrottle mode:"The RETARD mode is a form of thrust control. The throttles are driven to the idle stop when the AP goes into FLARE mode or when RA is less than 50 feet, flaps are greater than 31.5 degrees and ATS is engaged. Exit from retard mode is by setting throttles to reverse thrust or initiation of go-around mode."For my understanding, this converts to the following "logical" expression (that's not C or C++ or so):if (AP.Mode == flare) or (Flaps.Setting >= 31.5 and RA.Alt <= 50) then Throttle.Mode = retardSo, when ground sensors put the plane into flight mode (i.e. no weight on the main gear), throttles should go to retard whenever the plane is below 50 ft RA and flaps are extended in landing configuration.There's no indication that any other requirement is needed to get the throttles retardes (FMC entries etc.). I'd conclude that if in the described landing situation throttles don't retard, this must be either a bug in the MD-11 add-on or the throttle logic has additional properties that aren't in the manuals.

[Guest meirumeiru]

For my understanding, this converts to the following "logical" expression (that's not C or C++ or so):if (AP.Mode == flare) or (Flaps.Setting >= 31.5 and RA.Alt <= 50) then Throttle.Mode = retardSo, when ground sensors put the plane into flight mode (i.e. no weight on the main gear), throttles should go to retard whenever the plane is below 50 ft RA and flaps are extended in landing configuration.There's no indication that any other requirement is needed to get the throttles retardes (FMC entries etc.). I'd conclude that if in the described landing situation throttles don't retard, this must be either a bug in the MD-11 add-on or the throttle logic has additional properties that aren't in the manuals.

thanks a lot... that's exactely what I think too... but I have the strong feeling, that the FMS (at least in the PMDG MD-11 addon) has an influence on the ATS... and, I'd say, that this is a bug (either in the addon or in the documentation).

[mbucholski 9]

Maybe you could go through the 1st tutorial flight (again). I think it's a classical PEBKAC.

[ahinterl 1]

Maybe you could go through the 1st tutorial flight (again). I think it's a classical PEBKAC.

Matthew (nothing against you personally, your posting is taken only as an example), I don't think this helps in finding a solution for the original problem :( . The original poster describes a situation that's not in the tutorials. I guess that if the tutorials are followed, everything would be ok. But in this case, the autopilot is switched off and autothrottles are on intentionally.Though I don't know if such a landing ("1/2 on automatics") is performed in real life, it's legitimate to ask such a question since the system logic should act accordingly. Which, to my understanding when reading through all the stuff in this thread, it doesn't. So, it's either a bug, or someone needs to come up with an explanation what exactly is missing in the landing configuration to make the autothrottles work as expected. The aircraft manuals don't say much more than what I posted.I absolutely don't agree that this is "a classical PEBKAC"! Forum threads like this one, where a poster asks for help for a relatively simple problem setup, get this long because many repliers make the classical error of not thoroughly trying to understand and analyze what the problem really is.When one reads through this thread with an appropriate degree of attention, I think the problem is visible and can be understood. I'm missing some serious statements here other than assumptions or suggestions which are irrelevant for a solution. What I'd expect to read here are facts that can be backed with references, or simple "don't know" statements.I'm interested in this thread because I too want to know what goes wrong here. Maybe someone can enlighten us :(

[mbucholski 9]

Andreas, what I meant was that the original problem lies somewhere in the procedures the user is using, or a messed up install. As you can see, there is no green bar. I dare to say, that if the flow is followed and accomplished, everything should work just fine. And that is indeed how it works on my rig. I frequently fly the final approach by hand with ATS engaged and I never had any issues. That's why I pointed to the tutorial flights - they teach the procedures. To be a bit more helpful; what I do when on approach is to turn of the AP when established (so obviously APPR/LAND is engaged) and I leave the ATS enabled, then I just press the AP disengage button and bring her down.

[Guest meirumeiru]

... what I do when on approach is to turn of the AP when established (so obviously APPR/LAND is engaged) and I leave the ATS enabled, then I just press the AP disengage button and bring her down.

Yes... and that's what I don't do. I often don't engage the APPR/LAND... and, still -> if I'm flying from A to B, the retard works... if I'm flying around without a usefull flight plan, it doesn't (same for go arounds... with usefull flightplan but go around -> no retard anymore)... and I also tryed to use the APPR/LAND until it went into the "dual land"-mode... still no retard... so, from this follows, that the appr/land doesn't solve the problem. But, the FMS seems at a specific point into the flight to set an internal value of the ATS to "retard when < 50 feets" ... (that's what I think at least).And about the installation... I did install the FSX on my machine (Win7 x64), then the acceleration package and finaly the MD-11 ... everything worked fine... I had no errors during installation and I used the latest MD-11 with all patches included... I also didn't install other things than this MD-11 (except for some liveries, but that can't be an issue).I will fly other test flights to figure out, what could be the cause... but, it would definitively be easier to do that, by reading the source code :) ...oh and by the way... the "gear horn" button does also not work...

[mburkhard 23]

Rudolf,I've just completed a circuit to try to get what you have. I used standard operating procedures and my ATS retarded thrust just fine. I even deliberately set the cruise altitude in the FMC to a higher level I was actually flying to, so for the FMS I never reached CRZ. But anyway, retarded just fine. Looking at your screenshots you must be doing something wrong with your procedures. As you can see on your screenshots the FMS SPD is at 180kts, so you're plane does not know it's about to land. Hence there's no flare mode and no thrust retard. I wouldn't know of any software bug in this area, So I guess you have to double- and triple-check your procedures.Cheers,Markus

[Guest meirumeiru]

Rudolf,I've just completed a circuit to try to get what you have. I used standard operating procedures and my ATS retarded thrust just fine. I even deliberately set the cruise altitude in the FMC to a higher level I was actually flying to, so for the FMS I never reached CRZ. But anyway, retarded just fine. Looking at your screenshots you must be doing something wrong with your procedures. As you can see on your screenshots the FMS SPD is at 180kts, so you're plane does not know it's about to land. Hence there's no flare mode and no thrust retard. I wouldn't know of any software bug in this area, So I guess you have to double- and triple-check your procedures.Cheers,Markus

hi... ok, so my plane does not know, that it's going to land... but (!!!) ATS should retard, if you are below 50 feets and flaps > 31° or something... so, this should work, even if the FMS thinks, that I should climb... or do I misunderstand something here? ... as I said... it's a bug in the addon OR the documentation... because it's not written, that something else than the altitude and the flaps are influencing the retarding. ... so, even if I'm doing everything wrong and crash into ground or whatever... according to the documentation the retard should be commanded even then! ... that's it...I'm often flying at an altitude of 1-8 feets above the runway... and I don't have a retard... so, my landings are not completely wrong I think... and also in real simulators I never saw, an other procedure than what I do here... sorry... but I don't see where this should be my error...

[ahinterl 1]

Rudolf,I've just completed a circuit to try to get what you have. I used standard operating procedures and my ATS retarded thrust just fine. I even deliberately set the cruise altitude in the FMC to a higher level I was actually flying to, so for the FMS I never reached CRZ. But anyway, retarded just fine. Looking at your screenshots you must be doing something wrong with your procedures. As you can see on your screenshots the FMS SPD is at 180kts, so you're plane does not know it's about to land. Hence there's no flare mode and no thrust retard. I wouldn't know of any software bug in this area, So I guess you have to double- and triple-check your procedures.Cheers,Markus

Markus, the manual doesn't say anything that the autothrottle logic needs to be aware of flight mode changes or even the actual flight mode the plane is in. What is there is what I've described in my last post. I agree that the manuals aren't overly-informative and one needs a good portion of adding things that aren't explicitely mentioned. In the case of the AP, I'd add that the AP must have at least the information from the ground sensors that the gear is not compressed. If that wouldn't be the case, I'd expect it to behave somehow like on a takeoff when lower than 50 ft RA (i.e. more than 80 kts, so go to clamp mode).Maybe the designers of the MD-11 have put even more logic behind the systems. To better understand them, we'd need more precise information about the flight modes and the transition triggers/events between them as well as the dependencies of automatic modes from these modes.For me personally, the MD-11 is a much more "misterious" plane than others because of the "half-done" automatics. There's an old problem existing with FMSs and FMAs in such that they don't sufficiently inform the humans sitting in front of them about their goals. I had many occurrences of "strange" flight modes announced on the FMA that got active during maneuvers where I could only interpret them because I knew what happened before and what the goal of the maneuver should be. But I'm pretty sure that if I took a screenshot and showed that to a pilot, he wouldn't be able to decypher what the automatic tried to achieve. In such cases, there is more than only one possible way to interpret the FMA.I can think of the same happening "behind the scenes" where many more connections and dependencies between the logical systems exist than the manual expresses. If this is the case, I guess only the designers or engineers of the MD-11 are able to fully understand the plane and there will always be big surprises for us armchair pilots.