View Full Version : MD-11 stab trim vs. TOCG position: Any references available?

15th Jun 2006, 00:06
Hey all!

You've all been so helpful to me in the past when I've asked for information, so thanks in advance to all of you.

Is there any sort of printed references I could use a ROUGH estimate of the proper stabilizer trim settings for takeoff for CG positions? It's my understanding that anywhere between 18-32% of the MAC is the acceptable regime for safe takeoffs, so if there's any sort of printed chart or information someone could share with me so I can complete my MD-11 FDE for FS2004, that'd be great. I would REALLY appreciate any help! If I had an MD-11 FMS handy I'd use that but since I don't I have to rely on your expertise.

If there isn't any printed information available, could some of you MD-11 drivers give me some benchmarks perhaps? Say, typically, when your TO CG is 29%, what stab trim setting does your FMS give? If you could give me just a few benchmarks I can extrapolate for the rest. It doesn't have to be absolutely exact because it's more or less just a real fancy simulator game I'm working on, but I want to make this as realistic as I possibly can given I have limited access to MD-11s and I am not type rated on it.

What is the maximum stabilizer trim setting, positive and negative? I heard it was -4/16 ANU but I am unsure if this is correct. Does 1 ANU = 1.5 on the stabilizer?

And just another question, related. When I go do some plane spotting at Ontario airport in California I notice that landing MD-11s seem to have that stabilizer taking a real big bite out of the air. Does the MD-11 typically land with a lot of + ANU on the stab trim or I am not getting a very good view?

Thanks again guys!

17th Jun 2006, 10:44

I think, I found the right table you´ll need for your trim settings.
If you can give me your email-address, I´ll send it to you.
(Quality isn´t too brilliant, because my scanner is quite old :sad: ... but I think you can work with it.)

The range of the MAC for take-off is according to my books between 12%-34% (according AOM) or 14%-33% (according the load&trim sheet - that´s also our company limit).

Yes, you´re right. Usually we insert the T/O-CG (MAC%) into the FMC and then we will get the right T/O-Trim-setting on the TO/APP-Page.
The "green band" on the Stab trim synoptic (Config-SD or ENG-SD) will be displayed untill take-off as well. If you set the stabilizer into that range (+/-2° of the calculated value), the take-off warning "STABILIZER" won´t sound when pushing the throttles forward.

The normal range for the stabilizer trim is between 1° (AND) and -15.5° (ANU). Settings above these values will turn the indication on the system-display amber.
The max. settings are according to my books (LAMM-Schematics) between 1.3° (AND) and -16° (ANU).

I have no other information, that 1.0° "airplane nose up" (A.N.U.) means exactly a stabilizer setting of -1.0° compared to the zero-mark at the left side of the fuselage.
There is a black mark near the leading edge of the stabilizer on each side of the fuselage. On the left side, it marks the 0°-setting and on the right side of the fuselage, it marks the 3° ANU-setting (normal setting for parking and refueling).


The trim setting for the landing depends on weight, CG and flap setting. But I think a quite normal stab setting is around 10° ANU.

Hope I was able to help you for your project and I´ll send you the table as soon I´ll have your email-addr.


17th Jun 2006, 13:19
[email protected]

Thank you very much for all this information! I can't wait to see what you've got for me.

I just remembered that I have a copy of MD-11 LAMM schematics too! I need to start reading that thick thing. :)