boeing247 wrote on Feb 1^st, 2013 at 2:05am:

olli4740 wrote on Jan 31st, 2013 at 10:02am: boeing247 wrote on Jan 31st, 2013 at 12:31am: I too am having the issue with VNAV causing a rapid descent upon engaging, but I recall that someone (I believe it was Mark) had found a temporary work-around to get VNAV to properly engage until the next SP. What was the process, and does VNAV otherwise work in the current version? Thanks! Yes, there is a fix that makes the FMC revert from VNAV DES to VNAV CLB as it should be. But FMS-speed control in VNAV (both CLB and DES) is screwed up, too, in v1.0. So I changed my mind and went to FLCH, too. I wouldn't use V/S, because there's no speed protection in that mode. So is the problem that that the FMC is actually going directly to DES mode? I've only had one chance to try out the 777 since 1.0 came out, and I didn't check that.

I checked this again and I can confirm: The FMC changes to DES after engaging VNAV manually. You can check this for yourself by pushing the VNAV button on the CDU: The CDU will show the DES page, indicating the current submode is VNAV DES.  8-)

But I have to edit my former posts: After re-entering the initial cruise level into the CDU (don't forget that EXEC button!), the FMC does NOT change to CLB, it changes to CRZ instead. This gives an explanation for not adhering to the speed restriction (250/10000). The restriction is only valid for submode CLB, not for the CRZ.  :-/

But please check Mark's ('Markoz') posts in this forum, too: He's the CS 777-wizard around here ...  ;)

(selection of smilies made by my younger daughter, helping me on this post)