I use all de FMC data from the NGX Tutorial for the NGX 700 and also the NGX 900. Sometimes can I activate the VNAV knob., but mostly not. I checked the FMC but i cannot find a problem.LNAV is no problem. I tried everything.What do i wrong??? Hopefully can somebody help meRegardsJan

Without being able to see what you're doing, it's hard to know for sure. Some common thigns include not setting your v-speeds, takeoff flaps, flight altitude....

Usually the FMC should give you an advice what is missing, such as a route discontinuity. Did you really check that there are no discontinuities in the FMC?Do the following:

1. Set your Cruise altitute at first,
2. Choose a SID + Transition altitute,
3. Now apply your Flight Plan into the FMC,
4. Select a corresponding STAR + Transition altitute,
5. !important! Crosscheck whether there are any discontinuities, if there are no discontinuities the FMC will calculate the altitudes plus the FMC speed accordingly¹. If there should be discontinuities, the FMC will not be able to calculate the altitudes, because at a certain point he does not now how to proceed (because your flight plan usually ends somewhere in the air)

I suggest you to watch the following; well its in german but I guess you can still figure out what he is doing:

Cheers,Ensar B.__________^{1This can be seen in the FMC 'LEGS'Page. The FMC will assign a certain pre-calculated Speed+Altitute to every single waypoint. It should look like this (this is an example!):}

• SIE 232 / 14534
• CAMRN 250 / 10000
• ... ... / ...
• DDDDD --- / ------ <- Discontinuity!

Arm VNAVAn activated valid flightplan.PERF INIT page completed and EXEC'ed [Page header should be ACT PERF INIT)Valid FMC positionTWO flight directors ON, for arming on groundPS. DISCO's, VECTORS etc completely and entirely immaterial. You may have as many as you like. The FMC solvers will "bridge" across to the next waypoint assuming a straight line.

Arm VNAVAn activated valid flightplan.PERF INIT page completed and EXEC'ed [Page header should be ACT PERF INIT)Valid FMC positionTWO flight directors ON, for arming on groundPS. DISCO's, VECTORS etc completely and entirely immaterial. You may have as many as you like. The FMC solvers will "bridge" across to the next waypoint assuming a straight line.

TWO flight directors, that's what I've been missing! Thanks for the info.