That's a question! First I was irritated because of the necessity to use the speedbrakes a lot during the VNAV descend. So i made a descend from FL200 to FL030 with V/S 1000ft and the throttles in idle position. Slowing down was possible up to FL160 and then suddenly the N1 RPM made a jump from 34.9 to 40.0! After that happend a further slowdown was without speedbrakes impossible. The jump happend when the OAT changed from 3° to 4°C. - Is that a bug or is something wrong with my system?Have a look to the images.

There are other topics opened for the same thing.The problem was present before the SP1 on some configuration, SP1 solved it for some, created the problem on others.It is somethink I experienced with Hotfix4, after SP1 I have few times flashing Drag required only with winds not inserted in the des forecasts, but the plane is still able to slow down without needing drag.If you have a previous installer you could try to install again 737 without SP1.

Yes, I will do that, but first I would like to get an information, possibly from the guys from PMDG. May be I can keep the SP1 and doing something against this behavior...

Maybe you can open a ticket for this, but if you search, you will see that there are no solutions, at least here in the forum.

Hope that somebody presents a solution...

When descending on idle on thrust and FMA annuciation goes to arm I hit the F1 key to make sure throttle is at idle. It seems your hardware throttle could be interfering even if calibrated properly.

Me too, i always need the speedbreakes to bleed some speed, very annoying when reaching a fix with speed constrains ...

When descending on idle on thrust and FMA annuciation goes to arm I hit the F1 key to make sure throttle is at idle. It seems your hardware throttle could be interfering even if calibrated properly.

May be - but there are no such problems when I fly without SP1...

You are descending in V/S but the TMD says you are in a climb ?? It does not seem to know that it is in a descent.Your thrust mode is MCP SPEED.Have you tried this with level change ??V/S is only recommended for smal changes in altitude. ( 1000 ft or so )

Yes I tried it also with level change. In this case here with V/S I would like to have a constant sinkrate of 1000ft in order to see at which altitude the plane will have which speed. As we can see at no altitude it is slower then 241kn - throttles in idle position!

Sorry, I don't remember, I will try it tomorrow and then I'll tell you.

I haven't had this specific issue, but what did you use to export the data to that graph?

NO, THERE IS NO BUG!!!I have made a new installation of all: FSX and PMDG 737NGX. And all what I changed was according to the PMDG instructions and the settings of the fsx.cfg. Then I made two test flights. There was no jump of the N1! The slow down was perfect. Without speedbrakes I reached 3000ft with 201kn and 30.3 N1 RPM. One of the following programs must have caused the "bug" - may be!FSX GO - tweakerFlusiFix - tweakerFSUIPCEZdok Camera AddonUltimate Terrain X for EuropeFreeware sceneries of some german airportsIf somebody has the same problem I had may be he has also one of these programs in use. I don't know if and then which of these programs was responsible. The safety way to get rid of it is a new installation!ps. Hello Lee, I made screenshots and wrote the data in an Excel sheet.

FSX GO - tweakerFlusiFix - tweakerFSUIPCEZdok Camera AddonUltimate Terrain X for EuropeFreeware sceneries of some german airports

FSX GO - tweaker I don't have itFlusiFix - tweaker I don't have itFSUIPC - unregistered, yesEZdok Camera Addon yes I haveUltimate Terrain X for Europe Yes I haveFreeware sceneries of some german airports Only MunichIt is related to the ngx installer maybe. I had the problem with HF4, uninstalled and reinstalled wit no success.SP1 solved for me with the same softwares installed.

FSUIPC causes the "bug". I use a registered FSUIPC and that seems to be resonsible for the jump of N1 during the descent at about 15500ft! Then the N1 goes from 34.7 up to 40.0. And this forces to use the speedbrakes nearly all the time. It is an untouched version. What can I do to keep FSUIPC but without the IDLE JUMP?

FSUIPC causes the "bug". ....... What can I do to keep FSUIPC but without the IDLE JUMP?

A good first step if you've not already done so would be to report your findings to FSUIPC's developer so that they can be investigated and the problem fixed if your diagnosis is correct.Andy Lawton