HI !I've just passed to fsx now and when I want to initialize the irs with the fms, it says : NOT ALLOWED. I have flown the md11 in fs9 a hundred hours and never had that problem. What is wrong? the aircraft is with park brake, engine shut down. Thank you very much for helping.Chris Marty.

Do you have DC power applied to the plane? Without power you are going to have a hard time getting gyros to move.

Do you have switched all 3 IRS switches to on?@Lomaric: Do MD11s have normal moving gyros? No lasers?

I have done some searching but I didn't find any info in the PMDG manuals but if you look in the smartcockpit manuals, or more precisely the FMS manual http://www.smartcockpit.com/pdf/plane/boeing/MD-11/systems/0010/ and search for "not allowed" there will come up a lot of answers and a good way down there even pops up something about the IRU.Good luck solving your problem.Manfred

I know that this issue is almost always due to human error, however I just had this happen to me... and I'm perfect so it wasn't human error :-)

 

My situation somehow appears to have loaded with the GNS not functioning correctly.  So I had the same issue where I went to align my IRS using the "Initialize IRS" option on the CDU, and it returned a "NOT ALLOWED" error.  To fix, I selected REF on the CDU, then POS REF (LSK4L), then cycle the GNS Inhibit option (press LSK5R to inhibit, then again to Enable).  After this, I went back to the INIT page and was able to Initialize IRS successfully. 

 

Hope this helps!

It helped! (I'm a late comer to the MD11 and I just had this problem today)

 

Thank you for posting this!