En-Route altitude restriction

[Guest FrancoisH]

Hello there,Still a question about the MD11 I would like to solve.Sometime, on your flight plan, you have to use low en-route airways you can't fly above certain level... It's very current in France.So I'll have to maintain an intermediary FL untill I enter the high altitude airways.Is there a way to instruct this plane to do so... I tried entering two FL in the init page but the FMS chose itself the point where the plane is going to climb... may I set this manually elsewhere ?What I tried is to set a FL190 then FL230 along my route which did not work. Other way was to just set FL190, then set 230 on a point but other waypoints after the altitude restriction still at FL190.THank you.

[mfrantz 45]

Francois,You can use /S type restrictions during cruise to force the FMS to make the step climb at the point you want.Read the FMS manual page 40.44 for an explanation.

[Guest FrancoisH]

Ok, I'll anyway explain here a little better what I mean...There is my attempts.Black profile is the desired one.Low then High Airways profilehttp://img397.imageshack.us/img397/973/pmdgprofile1te9.jpgTo explain a little bit this illustration... My route start with low airways and continue with high airway... I try to set a climb "at or above" on MOU to reach FL200 or more after MOU for the hight airways (transistion between high and low is FL 195 in France and Spain (in second example below)).If I set a FL230 as final cruise level, profile will show like I put in yellow... trying to descend then climb again to the level of flight.If I set F190, it will descent after it reached the constraint I set as well.If I read you correctly I have to set FL190/FL230 as flight levels and a /S over MOU to change there.High then Low Airways profilehttp://img239.imageshack.us/img239/2115/pmdgprofile2jb5.jpgIn this second example I tried on the route to set a low airway on the second part... most logical was to set my FL390 as flight level and then a descent over PUMAL to FL190... but the problem is after PUMAL, the FMC start to calc a constant descent over next altitude constraint of the arrival, rather than maintaining FL190 and descending when the second "top of desent" will be reached... I had to set FL190 as a new Cruise level when passing PUMAL.Speed select bugLast, I found a bug (below is the screen).http://img388.imageshack.us/img388/91/pmdgbugfn7.jpgOn flight, I pressed by mistake the "Mach/IAS" button, then I put back online the FMS Speed...When I goes below the Mach/IAS transition, the AP was stuck in Mach mode and finally when I tried to select a speed, turning the button wasn't changing the value at all, unable to set the speed I want, whatever I Push or Pull the button, getting these really high speed values.Seems it's a bug.Regards.

[Guest FrancoisH]

Ok, on descent, I saw that the way to do it is the one I chose today... set a constraint to calulate the top of descent, level off at new CRZ lvl and then set again the CRZ alt to calculate the next ToD... so it's not managed by the FMC (neither the real one do it)... Now the question is still why the profile after this constraint is a slow descent rather than a delayed descent to keep as much as possible the constraint level until reaching most logical next descent point. Maybe it's the way the FMS is designed. I suppose it is reading the FMS pages related to that (thank you for the lin).There's always my last issue about the Autopilot bug... I did not understand why the Speed window was stuck with these high speed and wont change.Regards.