I have a flight programmed into the FMC. No problem here. The LNAV part of the flight works fine. When it comes time to start my descent do I have to keep changing the altitude on the MCP to start my decent and continue to change at each waypoint? I don't fully understand the relationship with the altitude setting on the MCP and how it interacts with the FMC. At the beginning of the flight I set the MCP to FL330 and the VNAV takes me there. However, when it comes to the descent part of the flight I have to keep changing the altitude setting on the MCP at each waypoint. Is this the way it is supposed to work?Thanks in advance to all who reply.Bill

Bill,I don't have the LDS767 which I assume you're using but with any FMC you need to dial-up the lower altitude when you're close to the ToD point. The MCP altitude always takes precedence over any altitudes in the FMC.Now how much lower you dial is up to you. If you're using default FS ATC and it clears you down to 3,000ft from FL330 (ucckk!) then you would dial-up 3000 on the MCP and the aircraft will descend at a suitable rate to try and meet the restrictions for each waypoint in the FMC. If flying on-line then dial-up the altitude you're cleared down to.If you don't fly online consider Radar Contact where controllers will clear you down in several steps akin to how it works in the real world. Click below for more info.Cheers,

Ray,Thanks for your reply. Let me add some additional information.1st I have and use Radar Contact, but not for this FMC test flight.2nd I am using Pilot In Command's 737-300.More Information:On takeoff I use TO/GA shortly after liftoff I turn on VNAV and LNAV and my MCP altitude is set for FL330. No problem here. The FMC takes me to FL330.On decent from FL330 set MCP altitude to FL280 turn on VNAV nothing happens. In order to decend I have to set the Vertical Speed on the MCP to say 1500 and the aircraft decends to FL280. This is the method I have to use to decend. Meaning I have to use the MCP to control my decent not the FMC.Flight plan:I created the flight plan in FSNAV and export it to FS2004. Load that flight plan into the FMC. Then I do, the decent legs have no speed/flight level. I manually add them to the flight plan and "exec". At this point every thing looks fine. I am using SID and STAR. Out of KLAS and into KSAN.So what am I missing?Again thanks in advance to all who reply.Ray thanks again for your reply.Regards.Bill

Hi Bill,Nice to hear you already have RC4 :-)It sounds like the PIC737-300 FMC is not as sophisticated as Project Magenta's where it computes an altitude for each waypoint in the plan.However, you said this...<>VNav should always be on. If you're not in VNav mode what mode are you in?Stay in VNav mode and when you need to start the descent press the DES option on the FMC (I'm guessing it has this) and press 'Descend Now'. This is assuming you are starting down before the ToD. If you're not (i.e. you want the aircraft to start down at ToD) then just dialup a lower altitude before ToD and providing you are in VNav mode and the next waypoint has a computed or manually entered altitude you should start down.Some of these problems may because the FMC is not calculating speeds/altitudes for the descent waypoints. Given this is a commercial product it really should. You might want to check with the PIC forum if this should be computed.Hope that helps.

Don't have the PIC, but there shold be a VNAV page in the MCDU that you can look at. It should show VNAV cruise as ACTive in cruise, and provide an estimate of ToD time and distance to go. After reseting the MCP alt, you shoould be able to watch the MCDU and see the distance to go go to 0, and then the VNAV DEScent page should go ACTive. If it doesn't, then there must be a problem in the FMS in computing a descent path: possible problems:1. No descent speed computed.2. No target waypontBoth of these should be shown on the DEScent page. If you can't see them, then check out how you are programing your FMS using your deocumentation. Assuming the DES page is ACTive, you should start desceneding and normally VNAV-PATH is annunciated in the FMA of the PFD. I think most of the MCDUs show the computed V/S required to attain the target alt on the lower right.The target altitude s generally the first waypoint after ToD with an altitude restriction set. If no waypoint has a restriction, in most cases the arrival airport elevation is used (though I think IRL it's supposed to be runway threshold + 50 ft).In addition there probably is a optimum path deviation indication on your PFD.I don't think the MCP alt is normally used for descent calculation; rather an alt capture to alt hold will occur if you descend to the MCP alt in VNAV.My experience with the FS FMS is that if you are maintaining an MCP altitude, VNAV can provide guidance, but as a mode for the AP it isn't that useful. Better to use a different mode.scott s..

Scott s,Thanks for your reply. It has brought additional information.After programming the RTE, PERF INIT, and TAKEOFF REF pages. Looking at the LEGS pages all the LEGS have speed/altitude calculated except for all of the descent LEGs. Why would it stop calculating at that point?I have registered for the Feelthere forum but I'm waiting for an email reply before I can post this there.As usual thanks in advance to all who reply.Regards.Bill