Boeing 737NG simulator seeking pilot...

[Jastapilot]

It's complex. Basically, the AP and the AT are not really associated. The AT, when it's on, chases the speedbug, depending on mode. We need to know AP modes, etc, but if you want the basics, the AT will work with the AP on or off, as long as the AT is on. Typically, on final approach we disengage the AP at any point and hand fly it to the ground. We also typically leave the AT on until 100'. Does that help?

[alphatango]

Hi Jastapilot,
No it does not realy answer my question...
I try again in other words... (you have to keep in mind that I usually speak french not english, so sometimes I am not very precise in my questions
In normal cruising flight with the MCP A/T "ON" Speed "ON", A/P engaged with heading "ON" and Altitude "ON" everything will be controled by automatic system including the trim wheel...
But if I just desengage the Altitude button and all the remaining stay "ON" who will control the trim wheel? Pilot or automatic system of aircraft...?
Is my question more clear?
Thank you,
Alain

[rightseatwonder]

by deselecting altitude on the mcp do you mean the ALT HOLD button?

if you choose to deselect any autopilot mode, I believe it reverts to a control wheel steering mode . In this case, you would have deselected althold, but remained in heading select. the A/P will still steer for the bugged heading, but you would have reverted to CWSP (control wheel steering pitch), in which the auto pilot ( which is still "engaged" but leveled down) will trim for the deck angle you have set with the control column. The A/T will still target MCPSPD.

I should stop trying to answer your questions! I might be shinning a light on my ignorance here!! LOL

[alphatango]

Hello,
Yes I meaned deselecting Alt Hold button and staying in a Autopilot heading mode....
Also I think that deselecting this Alt Hold mode would leave the altitude control to the pilot while the heading is still under AP controle. But maybe you are right, maybe it revertes to the CWSP. Then I would understand that the trim could be controled by the AP system if the CSWP is "ON"
But if I am right and that the CWSP in not enguaged automaticaly who controles the trim wheels... Pilot or AP system?
Still not solved... sorry...
But appoaching...
Alain

[rightseatwonder]

anytime the A/P is not controlling pitch, then you would be responsible for trim. remember if the A/P is engaged and you try to use the electric trim the A/P disengages.

Just wanting to make sure I had it right, the Boeing Vol 2 had this to say about it;

-Pitch CWS with a CMD engage switch selected-

The pitch axis engages in CWS while the roll axis is in CMD when:

*a command pitch mode has not been selected or was deselected (my bold)
*A/P pitch has been manually overridden with control column force....

So as I see it in your situation, you have A/P on (CMD annunciated) and you've deselected a command pitch mode (ALTHLD), then the above would occur... pitch axis engages in CWS, and therefore the A/P is still engaged, just leveled down and is still trimming for you... in this case for the attitude set by the pilot with the control column.

Hope this helps you out.

cheers
.RSW

[alphatango]

RWS,
This is very clear now and brings me an additionnal info I did not know...
I tought that the CWS was engage only by overridden with control column force, or by pushing this CWS button. I did not know if the AltHold button was deselected while still on AP, that the CWS was engaged automaticaly... This way it is normal and comprehensible that the trim be still controled by the AP system (in this case for the attitude set by the pilot with the control column) I understand perfectly what you mean...
Now this subject is closed... One more!
And a very big thank you RSW to you and Jastapilot...
Alain

[rightseatwonder]

yup there are a number of ways CWS can be activated.

selecting CWS on the MCP, deselecting a A/P mode on the MCP, over-riding the controls with force, also, when certain modes disconnect, such as VNAV or LNAV, it can level down into CWS. And if you are on a ILS approach, and VORLOC and G/S are annunciated on the FMA, and you detune the nav radio, it will level down into CWS pitch and roll and you'll have to do something quick! (don't ask me how I know!) haha

cheers,
RSW

[b767]

Alain, I am a 737NG pilot and sim instructor and I will be in Trois-Rivieres next summer.Would love to see your project and catch up.

[alphatango]

RSW, I add those infos to my knowledge... This is very new informations for me. I wil try to make it simulated in the sim. With the help of my friend Daniel (the pro for the programmation of the sim) we should be abble to make it very close of the real

B767 you will be welcome any time...
Just PM me and I will let you my personnal infos for contacting later...
Thank you to both of you there,
Alain

[Jastapilot]

I guess now is the time to bring up that after takeoff, with the AT engaged, but the AP OFF, the plane will autotrim if it senses a certain amount of pitch control pressure. You can still trim manually, but the Trim logic has it's own parameters and will trim on it's own if it doesn't like how you do it. Annoying as hell when you have it in your sweet spot and the plane goes and ruins it for you.

[alphatango]

!!!!! WHAT A SURPRISE! This is realy something completely new for me!
Just to be sure, what I unsderstand is ... with the AP off the pilot has the entire controle of the trim. But in some circumstances, the system could change automatically the pilot's trim ajustmemt to be in accordance to a certain system logic! Do I understand well. Is it right for all flight stages (climb, cruise, descent landing)?
I was 100% sure that when in a manual flight (no AP at all) only the pilot could ajust that trim!
Please confirm that I understand well. This is a very important input...
Thank you
Alain

[Jastapilot]

The pilot AND plane can trim the airplane in that condition. Now, I don't usually hand fly in every phase of flight, so it could be a takeoff 'thing'. Normally I like to have a fairly neutral trim position after rotation, normally, with a VNAP B departure we accelerate at 1000' agl, and retract flaps, then continue to 3000' at min clean speed. The problem(for me) at 1000' feet, is I don't usually trim, I just put fwd pressure on the controls, clean up the flaps, then allow the controls to go to neutral to continue the climb. It worked great on the -200, but on the -700, that's where it gets annoying. The plane senses I am putting fwd pressure, and without my permission, it trims to neutral again. So then I have to trim nose up again once the flaps are up. Note: the pilot overrides any trim input the plane puts in, and like I said, that could be a 'flaps out' logic only, but I'm not sure.

[alphatango]

Hi Jastapilot,
And thank you so much for all those precisions...
I will check with my friend (he is the specialist in programming, I am the student...) if this is possible to simulate that (both the aircraft and the pilot who has the possibility to trim the plane without AP...) If not the result will be...
- if no AP only the pilot will have the possibility to trim the aircraft.
- if AP is "on" and if the pilot changes the trim, the AP will disconnect.
So many thanks for your time...
And remember once in the air how much I would love to be in your place, just have a little think for me...
Alain

[Jastapilot]

Any time, as long as you don't make me hit the books! heheh.

[alphatango]

[Intentional Left Bank]

Jastapilot, I think you may be referring to the speed trim system. It trims the aircraft automatically when the autopilot is not engaged to attempt to return the aircraft to the trimmed speed when the speed diverges from the trimmed speed.

Vol 2 says it operates most frequently during takeoffs, climbs, and go-arounds when: airspeed between 100 kias and mach 0.5, 10 sec after t/o, 5 sec following release of trim switches, a/p not engaged, and the aircraft senses a trim requirement.

I remember thinking and perhaps mumbling aloud WTF? the first time I noticed it trimming without the a/p engaged.

[Jastapilot]

Bingo. It's a great system for an inexperienced, or dozing pilot, but for a guy who is anticipating 3 moves ahead, it turns into a pissing match... and there's no use arguing with a computer. It's like arguing with Blastor.

[Skymaster]

Bonjour Alain,

J'ai regardé votre projet et je peux vous dire que vous êtes un génie. Je suis un pilote de Dash 8 Q 400 et j'aimerais beaucoup voir votre sim, est-ce possible ? Je suis de Québec aussi.

Bonne journée.

[alphatango]

Quel bel avion que le Dash 8! Je le connais très peu me concentrant bien entendu sur le B737-800NG spécifiquement. Mais j'ai toujours été en admiration devant une telle beauté

Merci Skymaster pour tes bon mots...

Et bien sûr il sera possible de me rendre une visite. Envoies-moi simplement un PM avec tes coordonnées et disponibilités et je te contacterai... parles-moi aussi un peu plus de ton expérience etc...

Actuellement le simu est en ''...reconstruction'' car je suis à réinstaller certains modules comme les 2 FMC de même que les nouveaux throttle réels lesquels seront motorisés. Mais tout ça demande beaucoup de temps. Cependant j'espère qu'il sera redevenu fonctionnel d'ici une ou deux semaines... Du moins j'y fais mon possible!

Alors n'hésites pas à me laisser tes coordonnées et n'oublies pas que je suis toujours à la recherche d'un pilote qui a envie de partager ses connaissances et celà sur une base régulière.

Salutations,
Alain

[alphatango]

Hello Jasta Pilot, RSW, Intentionnal LB, Tiny Voices, Jer, Fou1oh, Frog and all those who have followed this tread.
First of all I want to thank you for your help all time long for this foolish project. Every time I asked for infos, there was always someone to answer my questions, sometimes very basics...!
Without your help and support from each of you, I could not reach the level of realism which I aspired. This is why I tell you a very special thank today.
Finally I think the result is very close to the reality, but the futur will tell me I hope when one of you will come at home to do a flight with me...
Just to keep you informed, the throttle are installed in the cockpit since about three weeks and now are working with a good level of realism I hope.
Also I add functionnal radios that make the experience more close to the real thing again.
Unhappily my web site is not up to date as I need many time to make it updated while working on the sim. But as soon as possible I will take a couple of photos just to let you see the result here
Again, thank you very very much to each of you
Alain