Heres the scenario:I'm quite happily in VNAV, climbing to an intermediate altitude given to me by ATC (ie not my cruise altitude). When I reach this altitude, if ATC haven't cleared me any higher, the plane will level off. But it will switch off VNAV mode, and engage MCP Speed and Alt Hold. Thats fine, but the problem is, when I am cleared higher, and I reset the MCP altitude, when I press VNAV, it doesn't enagage VNAV, it sticks with MCP Speed and changes Alt Hold to V Speed. The same thing happens if you are just about to acquire an intermediate level. You change the altitude, the autopilot automatically switches back to VNAV, but MCP Speed and V Speed are still active. You have to manually disengage VNAV and re-engage it again before N1 Speed and VNAV Pth come back.Is this a known problem? Is/Was it on the fix list for SU2?Thanks for any input.-Phil

Phil,I think this is/has been fixed for SU2Cheers,

Phil,I noticed the same behaviour, what I do as a workaround is the following:- ATC clears for higher altitiude- Change MCP to reflect new altitude- press Lvl Change- immediatly press VNAV.I find this works very well as an interim solution. Apparently by pressing lvl-Ch the logic gets reset in such a way that pressing VNAV afterwards then works correctly....You may want to give it a try!GreetingsJohan

Yes already worked out in SU2. In fact, it should not go MCP SPD but stay FMC SPD which it now does. The SPD window will stay blank FMA FMC SPD/ALT HOLD so all one needs to do is reset MCP ALT and engage VNAV ;)[h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-5/196432/winglets_lg.jpg

Based on the date and terminology of this thread I am guessing it is for the 737NG. I am having almost the same problem with the 747 passenger plane. The thing is the VNAV button stays lit and the FMA displays SPD. The only way I can get VNAV climb going is to select FLCH and then VNAV again. I am also having a broblem with VNAV descents. With VNAV engaged I select a lower altitude prior to the top of descent and select DES NOW. As I under stand things it should start descending at around 1200 FPM and continue until it catches the path or selected altitude. What happend is I went from 370 to 360 at full idle descent not 1200 FPM. Then I selected 10000 feet and the plane descended to 34900 and stayed there. The FMA would show IDLE, the throttles would retard to idle, the FMA would annunciate HOLD, the speed would start decreasing, the FMA would annunciate SPD, the throttles would come up and get the plane back to commanded speed, then the whole process would repeat. It did this until I caught the path and then it behaved like normal.I have had this problem every flight so far but this time I let it go to see what would happen. It seems to have problems with intermediate level offs in the climb and descent.

Sounds like you still have just the pax plane. The freighter fixed this DEC NOW feature for both the -F and the pax, but if you don't have the -F "patch", the pax plane is still broke.

Yup I only have the Passenger version. Anyone know if they are planning to fix this plane of is getting the F my only choice?

I got the Freighter and I still have to problem with the passenger plane. I haven't had a chance to try it in the F yet. Any thoughts?

The only reason I got the -F was for the patch and still always fly the Pax plane. Could you explain a bit more. Which feature is not working right?

A full description of the probelem is in the 5th post down from the top. I may have psoted prematurly because I know I have the probelem in the climb still. I did not test it in the descent where it was a bigger problem.

First off, I've noticed SU2 mentioned in this thread. What is that?Anyway, during a climb, if you use VNAV, once you reach your intermediate alt, the plane will level. You can leave the aircraft on VNAV and wait for your clearence. Once it is recevied, set the new alt in the MCP and then press the knob by holding the mouse over the centre of it. There should be a hand instead of the left and right arrows. The FMC should then tell the aircraft to climb.As for the DES NOW, I usually get some crazy decents unless the runway is selected in the FMC. Sometimes the aircraft will suddenly stop decending at a random alt instead of the selected alt. I just force the decent using the MCP and reactivate VNAV a little later or never again for that flight. Hope this helps everyone. Ryan Gamurothttp://www.precisionmanuals.com/images/forum/supporter.jpg

I think this is just procedural stuff. Keep in mind that Vnav works differently before and after 50 miles from TOD. For now, always have Vnav

The 747 VNAV works like the 737-800 I fly for a living. What you are talking about is altitude intevene. That will put your new altitude in the VNAV page when you are climbing to an altitude higher than what you originally selected for your cruise altitude. That is not the problem I am having.lets say I'm climbing to 34,000 but ATC has only cleared me to 24,000 which is set in the MCP. Either once the plane is level at 24,000 or when I dial in a new altitude in the MCP (I can't remember which) the light in the VNAV button will go out. Once I am cleared higher I press the VNAV button and the plane will start a VNAV climb to the new selected altitude and command the throttles to climb thrust. At least that is how it works in the 737 and 767 and I am making the assumption that is how it works in the 747 too. What is happening in the 747 is when I level the throttles go into SPD mode which I expect. When I am cleared higher and dial in the new altitude the VNAV button stays lit and pressing the VNAV button does nothing. It should already be out when I press the button. It should relight when I press the button along with the trottles going back into THR REF. What happens it the throttles only stay in SPD and no climb is commanded on the Flight Director. Actually the FD just seems to command whatever pitch I am at. To get it to back into a proper VNAV climb I have to select Vertical Speed which take it out of VNAV, the VNAV light goes out and it commands climb thrust. Then I can press the VNAV button which relights, the throttles go back to THR REF and the Flight director commands a climb.

Hi Tom, If I have the FMC's Vnav CRZ set for FL340 and the MCP set for FL240, on the way up my install captures FL240 in Vnav Alt/Spd and the Vnav button remains illuminated. If I then dial in a new altitude into the MCP, the Vnav button remains illuminated, but nothing happens. Pressing the illuminated Vnav button also, does nothing. At this point the only way to re-initiate a climb in Vnav is (to select a higher MCP altitude and) to press the MCP altitude knob. But be aware . . . this resets Vnav cruise page cruise altitude to that altitude in the MCP altitude window. If I let it go to this new FMC Vnav cruise altitude now, I will capture in Vnav Path/Spd. But if should (for some reason) dial down the MCP during the climb, I will capture in Vnav Alt as before. The Vnav button light never goes out. In my install, pressing the Vnav button does not initiate the climb or FMC Vnav cruise altitude reset. Pressing the MCP altitude knob resets FMC Vnav cruise altitude and initiates the climb/descent. The Vnav button light never goes out. I think this is working right, but maybe we both have a bug.

Oh and just to put correct information out, in the 737 when you level out at an intermediate altitude the VNAV button stays illuminated until you select a higher altitude. I wasn't sure about that in my previous post so I checked on my last trip. It's funny how you can fly a plane for so many years and not remember simple things about it.