Still can' get autothrottles to work correctly

[Guest Henri W]

Here is a screen shot of my setting. I had LNAV pressed in order to have the FD bars give me lateral guidance, however the AP was not switched on (no CMD message on EADI). All flying was done by hand. CMD means COMMAND, meaning that the aircraft is controlled by the Automatic Flight Control System (AutoPilot).Best regards,Henri

[Guest amerton]

Ok, I'll give it a go :-)>**********PLEASE NOTE: that at no time in the flight did I >ever press VNAV on this particular flight. I just want to >see if the A/T commands will obey me.******* cool>As usual, everything during the takeoff roll worked >perfectly. >As you said, I armed the A/P at 400' radio alt. In fact they said higher than 1000' !!! Are you sure you READ the manual right ?If the FD is on, then you'll have TO vertical and lateral modes engaged, and displayed on the PFD. Note that TO modes are assisted modes only on the 757/767, that is if you switch on the AP (CMD indicated on the PFD), the AP will engage in- VS / HDG HOLD if no VNAV / LNAV / FL CH mode armed / engaged- in the appropriate mode otherwise.>When I did this, the Speed button seemed to already be >pressed suddenly, althought I did not press it. This is normal behaviour : when the VS mode engages and the AT is in thrust lim mode, the AT SPD mode will engage.>point I noticed that the EHSI said the following things on >it: "F/D & CMD (lower right)(truthfully, I'm not sure what >CMD stands for-couldn't find it in the manual- do you guys >know?),See above : CMD means the AP flies the plane. >Anyway, A/T & SPD were in the lower left (as expected). To >my surprise, I noticed that V/S was also printed on the EHSI >(& I noticed that the V/S window on the right glareshield >read +350)! I couldn't disengage this! Fuly normal : as said above, as VNAV / FL CH modes not armed / engaged, the AP will engage the default modes VS / HDG HOLD. VS always engages at current vertical speed, hence the +350.Rule : you can only disengage a mode by engaging another mode. When you say I could not disengage VS, what vertical mode do you expect the AP to go into ????? To get put of VS, you have to go to ALT HOLD, FL CH or VNAV>The A/T nover even came close to approaching my 250 knot >restriction in the window! It just kept bleeding speed. Read on>Finally, the only way I could clear the V/S window was to >press the Hold button for the altitude (it held at 5000ft >since that was the altitude currently in the window). Chris, sorry for the wording, but what you write is nonsense. ALT HOLDwill hold at current altitude independently of what is in the ALT window. >When I did this, the A/T disobeyed my wishes by blasting all >the way through the 250 speed restriction all the way to the >red line limit. >At this point, used the speed brakes to slow down - & once >again, it would continued to bleed speed until dangerously >low. I MADE SURE to notice that SPD was still on my EHSI - >it was. I still had a temperature reading on my FMC (13 >degrees C) >I tried several times to "reset the speed button" by turning >it off & then back on to see what would happen (again, every >time I did, I made sure to see if the SPD indicator was on >the EHSI, & it was) & each time I would reset it would blast >through the 250 kt limit in the window. Also, if I "reset" >the switch with my joystick throttles at 0, then when I >would rearm the SPD button, it would read "IDLE" on my EHSI >(not sure if it is really supposed to read this way or not >in such instances). When the button was reengaged, it would >only continue to bleed speed slowly. If you want to turn off speed button, disarm the AT.>The only thing I did that may not have been called for was >ont 2 occasions, I hit the alt know inward to see if it >would bring me to a new alt, & it did not.dial target alt, press VS if not in VS mode, there you go, no need to press ALT knob> However, this >should have no bearing on the A/T. Right-O>>Gentlemen, I really appreciate your input & your patience >with my situation. Yes.>Can either of you reccommend a really simple exercise or >test I can perform to just test the basic functionality of >the A/T?Well, this is exactly what the 2 gents did.>I am really starting to wonder if maybe it is a hardware or >software problem at this point. :-( Or maybe it is >something really simple I have not thought of yet. I seem >to be getting no where & am losing heart. Maybe if you can >reccommedn a simple test, I can find out for sure if the A/T >will work for me. OK, now : copy the contents of the 757AT.txt file in the PMDG dir and paste here.anthonyAnthony MertonPrecision Manuals Developmenthttp://www.precisionmanuals.com

[Guest]

A huge thank you for all of you for your patience with me. To my surprise, this has been so much harder to learn than the 777! (Is this normal?)I will spend several hours printing out & re-reading, re-re-reading & re-re-rereading your excellent & helpful posts. I will practice & see if I can learn this complicated birdie. I am glad to see that it is just me & my ignorance at this point & not a problem with my computer, or the hardware, & certainly not the software. I am learning a GREAT DEAL from all of you & I thank you endlessly for your assistance. I'll let you know how it goes.Again thank you. :-)Gratefully,Chris

[Guest]

Dear Anthony (and all):Some breakthroughts tonight thatnks to you & your fine help, not to mention the great help of Mike & Paul:Some questions- I tried to see what was in the 757AT.txt file you mentioned & this is what was there:0.0050.0650.0001631.5Nothing more. Is this correct?Now for some comments & questions.I was able to clearly see the relationship between V/S & the autothrottle mode for the first time & it functioned exactly as you said - if a V/S was dialed in (or active), the auto throttles did everything they could to maintain the V/S regardless of the speed selected with the speed bug. Also, it was GREAT when doing a FLCH. It would ALWAYS try to capture my speed bug setting. Here's where I ran into problems however. Once it finally captured my altitude, (and after the HLD light illuminated as expected), the A/T seemed to not want to follow my speed bug any longer. As long as I was changing altitudes w/FLCH, it would be perfect, but once it captured my altitude, it seemd to not follow the speed bug any longer. I checked in those instances & saw that SPD was listed on the lower left of my EADI beneath the green A/T symbol. I feel like I am very close to getting this all figured out. ***********MOST IMPORTANT QUESTION OF THE NIGHT: *****************What do I have to press to get the A/T to respond to the speed bug when I am flying at a level altitude? BTW, for all my experimenting tonight, I decided to skip the use of VNAV for simplicity.Now for some other questions:1) In the 777 manual, there was a list or diagram of every possible listing that could appear on the PFD. Is ther a similar list somewhere in the manual for the possible green listings on the 757 EADI? If so where can I find it?2) Which classifications of green symbols appear on the lower left of the EADI, & which category do the ones on the lower right fall into (for example, T/O is on the left AND right during an EPR takeoff roll)?3) What does it mean in green when it says IDLE on the loer left of the EADI4) Finally: What does F/S stand for on the EADII cannot thank all of you enough for helping me to understand this stuff. I work really hard at it, but my tiny mind can only comprehend so much! :-) I am very grateful for all of you for your assistance!Very sincerely,Chris

[michal 44]

>***********MOST IMPORTANT QUESTION OF THE NIGHT: >***************** >What do I have to press to get the A/T to respond to the >speed bug when I am flying at a level altitude? Chris,Assuming that your 757 is functioning correctly you really don't have to do anything. Once the altitude is captured (and vertical mode becomes ALT HOLD) the A/T should switch automatically to the SPD mode regardless what your climb mode was before. The SPD button should then illuminate.Michael J.

[lefteris 70]

...the A/T should switch automatically to the SPD mode regardless what your climb mode was before. The SPD button should then illuminate...Which it does, for every other user ;-).Chris- I think you are still a bit confused regarding autopilot modes:The AutoPilot controls THREE DISTINCT and DIFFERENT things:a) the SPEED mode:( The LATERAL mode (Roll)c) The VERTICAL mode (Pitch)The AutoThrottle (Speed) is working INDEPENDENTLY of the other two controllers. That means that if you have a Speed selected, it tries to maintain that speed regardless of other stuff... so you can be flying the aircraft WITHOUT the A/P, but WITH the AutoThrottle.I hope this makes a little more sense...

[Guest]

Actually, I really do understand this part of the concept from the 777. Howeer, based on my experiences last night described above, can you think of anything that I am doing incorrectly to get the A/T to function correctlywhen ALT Hold is working? I kept waiting for the speed bug to work once that happened, but as you read above, it only seemed to follow the speed bug when I was initiating a FLCH. Once the altitude was captured, it seemed to stop working again. :-(. I am SURE I must be doing something wrong - based on what I wrote above, can anyone figure out the last part of the puzzle? :-( I feel like I am really close to getting this. I know I don't need the A/P to be controling the Vetical & lateral modes to get the A/T to function. One quick question:As you stated above The AutoPilot controls THREE DISTINCT and DIFFERENT things: a) the SPEED mode :( The LATERAL mode (Roll) c) The VERTICAL mode (Pitch) The AutoThrottle (Speed) is working INDEPENDENTLY of the other two controllers. That means that if you have a Speed selected, it tries to maintain that speed regardless of other stuff... so you can be flying the aircraft WITHOUT the A/P, but WITH the AutoThrottle.If the A/P controls 3 modes (including speed), then how can it be thatone fly the aicraft without the A/P? You still need to engage it to to get the A/T to work don't you? This part does confuse me a little bit.Lastly, did anyone come up with a place that lists all the possible annunciations & their manings on the EADI, & which markings go on the lower left & which go on the lower right? Thanks a ton everyone.Sincerely,Chris

[michal 44]

>If the A/P controls 3 modes (including speed), then how can >it be that >one fly the aicraft without the A/P? You still need to >engage it to to get the A/T to work don't you? This part >does confuse me a little bit. Chris,You start confusing me with your questions ...A/P controls speed with the pitch, if you happen to be using the A/T as well then speed can be controled with the thrust as well.Return to my basic tests. Be careful with statement "engage A/T" since you may mean wrong things. A/T can be ARMED as the position of the switch indicates. Then A/P can "engage" it automatically based on vertical mode selected. Or if A/P is off a pilot can engage it - but only in the SPD mode. The other approach for you is to stop reading all these posts and simply play with the aircraft. You will learn much more by experimenting with all the modes. This is how I learned this panel - not by reading manuals.Michael J.

[Guest]

INCREDIBLE NEWS!!!!!!!!!!!!!!!!!!!I KNEW SOMETHING WAS SO VERY WRONG!!!!!!!!!!!!!!!!:-)I just kew it!!!!!!!!!!! It WAS NOT ME ALL ALONG!!!!!:-)Michael, I just reread your excellent post & tried the most basic test w/ the A/T - & it STILL didn't work!!!! I tried pointing the nose down, then up, all the while the A/T was armed. NOTHING HAPPENED!!!!!! THE A/T WOULD NOT RESPOND AT ALL - in fact it NEVER even changed the RPM of the engines whatsoever!!!I KNEW THIS WAS WRONG!!!! So, on a lark, I simply reinstalled the PMDG 757 - & it seems to work PERFECTLY now!!!!!!!!! :-) :-) :-) I have had hundreds of hours on the 777 & knew & was doing most things correctly with the 757. Then, when the A/T seemed to not respond at all...................... I KENEW something was so very wrong becaue I couldn't even get the most basic test to work at all!!!It seems to be perfect now!!!!!!!!!!! :-) :-) :-) :-) :-) :-)Nonetheless, I did learn a lot from you all about the relationship between one mode & another (disengaging one & replacing it with another) Thank you all so much. I almost can't believe it after all we all tried to do!!! Thank you all soooooooooo much!!!!Most sincerely,ChrisPS: which order are the modes listed on on the EADI? the 777 listed them (from lest to right across the top) in this order: THR/ROLL/PITCHI guess these are listed fromtop to bottom on the 757? Which order are they in, & which are on the left & which are on the right?Thanks again!!!!

[Jet Tech 31]

Chris,You know, I thought about asking you to try re-installing a while back in this post but it never made it to the thread. Glad this finally worked for you. Well the good news is you should have a good understanding of the A/P and A/T system!As far as mode annunciation on the EADI goes here is how it goes.Left side upper has A/T displayed when A/T is active. Directly below it is the active A/T mode (SPD,EPR,FL CH) Directly below this is the A/P-F/D Pitch Mode (Active in Green, Armed is in White). On the right side, upper is F/D for Flight director on and CMD for A/P in Command. Lower Rt is for A/P-F/D Roll Mode (same as Pitch Mode Active Green, Armed White).Now Go have Fun.RegardsPaul

[michal 44]

Chris,Glad you got it all figured out. Often it is something silly.As to the order - just look at the pic you posted above - it is all there in black & green :-)Michael J.

[Guest]

Chris,just to make sure everything will work now, here is one small note from my side, below your following your statement:>Michael, I just reread your excellent post & tried the most >basic test w/ the A/T - & it STILL didn't work!!!! I tried >pointing the nose down, then up, all the while the A/T was >armed. NOTHING HAPPENED!!!!!! THE A/T WOULD NOT RESPOND AT >ALL - in fact it NEVER even changed the RPM of the engines >whatsoever!!! As long as the A/T is armed only, you won't notice any activity because there is no activity.After arming the A/T you have to engage it by selecting a mode (speed, EPR or VNAV) to make it actually work.Let's say you want the A/T to manage a dialed in speed. First you need to dial in your desired speed, then you need to arm A/T and after these two steps you need to select the speed mode to engage A/T.Happy flying and best regards

[Guest]

Actually, I knew that - just poor wording on my part (Mike said to hit EPR & or SPD in the test I performed)! Besides, after all these hours of playing around with this A/T stuff, I'd BETTER know it by now!!!!!! :-)Thanks Ed!Sincerely,Chris

[AlaskanFlyboy 7]

Yeah, I beleive the reason the temperature is important is that the FMC needs it to calculate it's density altitude.-Shane Morgan

[Guest]

I've had alot of success with the 757's automation. After going through the whole FMC setup, etc. etc. I can then hit EPR to start my takeoff roll. I then manually fly the aircraft to intercept my course and hit LNAV. Away it goes!Once though the EPR failed to engage after I *thought* I had done everything right. I reviewed all my settings and still couldn't get it to work. I restarted fly, repeated the procedure and everything worked. So maybe there is a bug but I have only seen this just once. Could easily be user error.The 757 is a joy to fly. The only problem I'm having is I can't get the aircraft to automatically descend at a reasonable FPM. I'm always having to manually intervene with the airbrake. Even though the manual says the DES NOW option of the FMC causes a 1250 fpm descent, it would seem to me that it should really set a correct fpm depending on how far out you are. But, I suppose the PMDG way is the way the real 757 works so.....If anyone has any ideas.....Tim Dobrowolsky