I save several flights about fifteen minutes from landing, so that I can return to them whenever I want, and land. For almost all of my flights, I have no problem reloading them. But for one of them, the VNAV Disconnects every time I reload it. I see the VNAV DISCONNECT message on the FMC, and the CWS P message. All the target altitudes and speeds are displayed on the FMC, but none of the estimated altitudes and speeds are displayed. In addition, this always happens when I save flights on this SPECIFIC route from KOAK to KLAX.Any ideas on how to reenable VNAV?Thanks.

Try resetting the CRZ ALT to your current altitude.

Thank you for your reply. Unfortunately, setting the CRZ ALT to my current altitude does not work. My current altitude is 5000 ft. When I enter this into the FMC, it automatically changes it 11000 ft.

It's some sort or limitation of the saving feature. I have it almost all the time and hence never save a flight in mid air anymore... Someone from PMDG posted sometime ago that there isn't much you can do about it.

The interesting part is that it only occurs on this route, with this specific approach. I wonder if there is anything I can do before I save the flight to avoid this from happening when I reload it.

Check for any crossing restrictions that are higher than your altitude. You should get some sort of error message if the FMC doesn't like your cruise alt selection.

I had your same problems, there seams to be some limitations when saving a flight.David Di Domizio

This happens when I do the SADDE SIX arrival at KLAX. Here is the link from Airnav: http://155.178.201.1.../00237SADDE.PDF. The chart says to cross SYMON at 12000 ft at 280 knots. When I enter this into the fmc during preflight, it returns, UNABLE 280K at SYMON. What do I do to fix this error?

Edited February 25, 201214 yr by ethanpilot787

I just noticed that this problem only occurs after T/D. If I load the flight right before T/D, the VNAV is active. Anywhere after T/D, and the VNAV disconnects.

For me it happened at KFLL doing a SID. I don't remember which one but I was able to do many other departures from a saved flight where VNAV behaved just expected.I have no clue why it works for some and for others it doesn't!David Di DomizioIf you search this forum you can see I also posted a video of the problem.David Di Domizio

Saving/reloading any flight with SID/STAR saved in fmc will result in weirdness. It is pretty much always recoverable. I'm on tapatalk so I'm not sure how to link to another post but search VNAV disconnect and I've posted a workaround. I can get the flight back in 95% of cases now with VNAV. you have to fool the FMC. As Matt says, alt restrict will mess it up. The only times I can't recover are at or close to t/dBut you can hand-fly it (or use lvl chg) from there to the next w/p and reconnect hopefully