This has been bugging my head for a while now so I thought I should finally post this. First of all, I usually start my flights with 2/3 pax load and not above 50,000 lbs of fuel, as I don't normally do long hauls. I set the STAB trim to the value indicated on the TO/APPR page, which is around 5.2-5.5 . I engage the ATS and apply full throttle (I don't use any FLEX data but I'm thinking to start using it soon). As the altimeter rises, I retract the gear and follow the FD pitch which usually commands a 17.5 nose up degree pitch. Okay, so I'm holding +17.5 degrees until 400 feet RA, when I engage AUTOFLIGHT and release the pressure on the yoke. This is when the plane starts to rise and hold a 25+ deg pitch up attitude, rapidly losing airspeed to Vmin. The airplane starts to lower the nose, but way too slow (about 1deg/5 seconds) to maintain an airspeed. Not even engaging PROF at 1500 feet RA doesn't make the plane to lower the nose faster. So, how do I get out of this deteriorating situation? - Either the plane reaches the initial level off altitude and the airspeed is rising again - or - the airspeed decreases to Vmin, which is the point the plane will start to lower it's nose like it should be in order to avoid the stall. Then, the rest of the flight goes as planned (normal).The aftermath:I think that the STAB trim is the problem here. Having it set to 5.5 it makes the plane to pitch up so steeply after engaging AUTOFLIGHT and the AP doesn't have the power to lower the STAB trim quickly after takeoff in order to climb normally. But then, why is the FMS wanting a 5.5 STAB trim on takeoff if it knows it will deteriorate the initial climb?I hope I am not the only one having this problem and I also hope a solution can be found soon. If I takeoff manually until the initial level-off altitude, then I have no problems. I apologize in advance for the long write-up as it is a bad habit of mine.

This has been bugging my head for a while now so I thought I should finally post this. First of all, I usually start my flights with 2/3 pax load and not above 50,000 lbs of fuel, as I don't normally do long hauls. I set the STAB trim to the value indicated on the TO/APPR page, which is around 5.2-5.5 . I engage the ATS and apply full throttle (I don't use any FLEX data but I'm thinking to start using it soon). As the altimeter rises, I retract the gear and follow the FD pitch which usually commands a 17.5 nose up degree pitch. Okay, so I'm holding +17.5 degrees until 400 feet RA, when I engage AUTOFLIGHT and release the pressure on the yoke. This is when the plane starts to rise and hold a 25+ deg pitch up attitude, rapidly losing airspeed to Vmin. The airplane starts to lower the nose, but way too slow (about 1deg/5 seconds) to maintain an airspeed. Not even engaging PROF at 1500 feet RA doesn't make the plane to lower the nose faster. So, how do I get out of this deteriorating situation? - Either the plane reaches the initial level off altitude and the airspeed is rising again - or - the airspeed decreases to Vmin, which is the point the plane will start to lower it's nose like it should be in order to avoid the stall. Then, the rest of the flight goes as planned (normal).The aftermath:I think that the STAB trim is the problem here. Having it set to 5.5 it makes the plane to pitch up so steeply after engaging AUTOFLIGHT and the AP doesn't have the power to lower the STAB trim quickly after takeoff in order to climb normally. But then, why is the FMS wanting a 5.5 STAB trim on takeoff if it knows it will deteriorate the initial climb?I hope I am not the only one having this problem and I also hope a solution can be found soon. If I takeoff manually until the initial level-off altitude, then I have no problems. I apologize in advance for the long write-up as it is a bad habit of mine.

Have you read the Tutorial? Plus using full throttle at those weights is not ideal and yes using a "Flex" take off would be a good idea.Martin Buzzell

I had the same thing a long time ago. My fault was having the wrong weights in the FMC, therefore giving a wrong stabtrim entry feedback.After I realized what I'd done wrong I changed the way I did things, e.g. use the loadmgr, set the load and fuel, write it all down, start the MD-11. Set the correct fuel in the PMDG options in the menu.Set the correct entries in the INIT of the FMC and watch the middle CONFIG EICAS tell you what the correct CG should be (99% of the time it's the same as the loadmanager gave you).Then enginestartup, set the stabtrim, taxi to the rwy, set the autoflight and go.btw: I always use the FLEX, but even without FLEX I get a correct pitch-up.

Try reducing the stab trim setting by about 0.5 units from the recommended setting (ie if the calculated value is 5.6, set 5.1 instead).

Have you read the Tutorial? Plus using full throttle at those weights is not ideal and yes using a "Flex" take off would be a good idea.Martin Buzzell

Well, I read the tutorial the day the PMDG MD-11 was released and I am an experienced MD-11 flier. It's just the recent 1.2 update when the plane's takeoff performance was changed that I started to notice this behavior.

I had the same thing a long time ago. My fault was having the wrong weights in the FMC, therefore giving a wrong stabtrim entry feedback.After I realized what I'd done wrong I changed the way I did things, e.g. use the loadmgr, set the load and fuel, write it all down, start the MD-11. Set the correct fuel in the PMDG options in the menu.Set the correct entries in the INIT of the FMC and watch the middle CONFIG EICAS tell you what the correct CG should be (99% of the time it's the same as the loadmanager gave you).Then enginestartup, set the stabtrim, taxi to the rwy, set the autoflight and go.btw: I always use the FLEX, but even without FLEX I get a correct pitch-up.

The weights are correctly set up. Just an FYI, if you have an incorrect TOCG set in the MCDU it will give you a message.

Try reducing the stab trim setting by about 0.5 units from the recommended setting (ie if the calculated value is 5.6, set 5.1 instead).

That is just what I'm thinking to do on my next flight in order to confirm the theory about the FMS wanting an incorrect STAB trim. I'll do this. Thank you all for your suggestions.Maybe my MD-11 installation is corrupt. I recently reinstalled my OS and this is when the problem appeared. I installed the 1.0 version and then directly the 1.2 update. I skipped the 1.1 because it was no longer available on the website and because the 1.2 update replaced the same files as the 1.1 update with newer versions. But still - could the fact that I skipped the 1.1 update be the problem here?In order to duplicate this, is anyone that has installed both the 1.1 and 1.2 updates willing to do a test for me? Just load the plane and send the following info from the Load Manager: 2/3 pax and 50,000 lbs of fuel. Then program the FMC as on a normal flight (complete the F-PLN INIT, WEIGHT INIT, enter your route on the F-PLN page and then enter the details on the TO/APPR page). Then let me know if on the TO/APPR page the FMS wants a 5+ STAB trim. You don't have to complete the flight, just complete the preflight phase and let me know what is the value the FMS wants for the STAB trim.If anyone is willing to "waste" their precious time in order to help me out and do as I said above, I would appreciate it incredibly much.

when I engage AUTOFLIGHT and release the pressure on the yoke.

Marius,you should not do that. The airplane should be trimmed out, meaning any pressure on the yoke being trimmed away before engaging auto flight.Regards,Markus

Markus, just to make sure I understand correctly, so I have to release any pressure on the yoke and then engage AUTOFLIGHT? This makes sense. I'll try a flight tomorrow and I'll let you know the results. Thanks a lot for your suggestion.

Markus, just to make sure I understand correctly, so I have to release any pressure on the yoke and then engage AUTOFLIGHT? This makes sense. I'll try a flight tomorrow and I'll let you know the results. Thanks a lot for your suggestion.

That's correct BUT make sure that you use pitch trim so that the airplane maintains the pitch commanded by the flight director when you do release the yoke. In other words, the airplane has to be able to fly precisely on the flight director commands with your hands off the yoke, before you engage the autopilot.Markus

In order to duplicate this, is anyone that has installed both the 1.1 and 1.2 updates willing to do a test for me? Just load the plane and send the following info from the Load Manager: 2/3 pax and 50,000 lbs of fuel. Then program the FMC as on a normal flight (complete the F-PLN INIT, WEIGHT INIT, enter your route on the F-PLN page and then enter the details on the TO/APPR page). Then let me know if on the TO/APPR page the FMS wants a 5+ STAB trim. You don't have to complete the flight, just complete the preflight phase and let me know what is the value the FMS wants for the STAB trim.If anyone is willing to "waste" their precious time in order to help me out and do as I said above, I would appreciate it incredibly much.

Marius,I "wasted" some time on this.For the stated conditions in FSX I find a required STAB setting of 6+, depending Flap setting.For FS9 the required STAB setting is in the 5+ range, also depending Flap setting.So two questions in order to waste some more time:- What sim are you refering to, FS9 or FSX?- What is your TO Flap setting?Whatever the FS version is, you should be able to center the FD pitch bars, without the use of pitch trim, then release the yoke force, before engaging the AP. That's how the real thing works when starting the TO roll with the correct STAB setting.Regards,Harry

Hi markus,reading this thread brought a question about the LSAS. why not putting the plane in the right attitude and releasing any pressure on the yoke without using the pitch trim wheel ? If I understood well the LSAS should then do the job of keeping the correct pitch. Is the pitch trim still required when large attitude change are involved ?cheersJulien

I think part of the problem may be an impatience to get the craft on autoflight. FLEX is usually always a good idea for light takeoffs (the birds got a lot of power to be used). The procedure I use on takeoff - holding short of the runway I arm TO CLAMP and NAV only. Advance the throttles till the ATS takes over. when Vr comes along, slowly add back pressure until the you hear the mains break free and hold it at that pitch attitude. Once the gear is retracted, begin to pitch into the F/D and back it up with the airspeed to hold around V2. At this point I trim off any pressure on the controls (which is usually a ton of nose down). Once i've trimmed, I then come over and engage PROF which activates climb power and I can let the nose drop to speed up through flap retraction. After all this is done and the airplane is trimmed out and stable I switch it over to AUTOFLIGHT. Only a few times have I had the nose come up on me and send the LSAS into speed protection.. This is usually because FMS SPD hasn't engaged and the F/D wont change to reflect a climb out configuration, or accel to 250kts. All in all I believe for this airplane, it takes a bit of nurturing to get setup in the climb and on autoflight. Im usually not engaging all automatics until around 3-4 thousand feet.Hope this helps a bit!Tom Moretti

reading this thread brought a question about the LSAS. why not putting the plane in the right attitude and releasing any pressure on the yoke without using the pitch trim wheel ? If I understood well the LSAS should then do the job of keeping the correct pitch. Is the pitch trim still required when large attitude change are involved ?

Julien,indeed basically there's no need to use pitch trim after take-off. As Harry mentioned you should be able to centre the pitch bar without it. Two reasons for this: 1) The TO Stab Trim setting is calculated for V2+10. 2) if there are small corrections necessary LSAS will deal with them.BUTthis only works if there's (almost) no pressure on the yoke. The original poster mentioned having to release pressure on the yoke. Now you're right that one could delegate the job of eliminating that pressure to LSAS. However this is not practical if there's a substantial pressure present. The LSAS does have a certain delay before pitch is maintained so if the stabiliser is off by a good amount releasing the yoke to get LSAS to work will not immediately maintain the current pitch.If you need constant pressure to maintain a certain pitch you have to use the manual trim switches to move the stabiliser while gradually easing off the pressure until you are in a range where LSAS can take over.However if the TO trim setting is correct and you do fly V2+10 then manual pitch trim should indeed not be necessary and LSAS will maintain whatever you have.Regards,Markus

Julien,indeed basically there's no need to use pitch trim after take-off. As Harry mentioned you should be able to centre the pitch bar without it. Two reasons for this: 1) The TO Stab Trim setting is calculated for V2+10. 2) if there are small corrections necessary LSAS will deal with them.BUTthis only works if there's (almost) no pressure on the yoke. The original poster mentioned having to release pressure on the yoke. Now you're right that one could delegate the job of eliminating that pressure to LSAS. However this is not practical if there's a substantial pressure present. The LSAS does have a certain delay before pitch is maintained so if the stabiliser is off by a good amount releasing the yoke to get LSAS to work will not immediately maintain the current pitch.If you need constant pressure to maintain a certain pitch you have to use the manual trim switches to move the stabiliser while gradually easing off the pressure until you are in a range where LSAS can take over.However if the TO trim setting is correct and you do fly V2+10 then manual pitch trim should indeed not be necessary and LSAS will maintain whatever you have.Regards,Markus

Markus,I fully understand your explanation above. Have been on this subject before the 0055 update in this thread:http://forums1.avsim.net/index.php?showtopic=240770posts 35,36 and 37.Now with the 055 update, I still find the TO STAB setting being too much nose up.To test this the procedure in post#37 will show this (again).Starting a take-off with this incorrect stab setting, may require manual pitch trim input to align the stab and elevator within 5 degrees. A condition for LSAS autopitchtrim to operate.Some suggest to set the stab 0.5 units less nose up, sure it helps.Decreasing the stab setting by 1.9 or 2.0 (keeping it just inside the green band) will give you almost the correct setting.Hope to be of help.Regards,Harry

thanks guys for the answerscheersJulien

I agree with Harry. Reducing the trim-setting (in my case 1.0 less than FMC calculated) helped me to achieve a perfect take-off, together with Bryan Schleipen's Flex tables for reduced take-offs and ideal flap setting. I wonder why. Markus, may we ask you to comment on this once more. Much appreciatedRegardsTom Castelberg