Thread: CDU 397C flush and VNAV issues
08-03-2008, 07:46 PM #1
CDU 397C flush and VNAV issues
With CDU 397c I have noticed the following issue. We often do turn-around flights where we don’t reset the sim, but rely on the CDU doing a flush on touchdown so that we can program the next flight once parked. CDU flush is turned on. What we’ve noticed is that the last waypoint / leg of the previous flight does not flush. It does not appear in the CDU legs / RTE pages BUT it will often be displayed on the ND with a blue dotted line to it, and sometimes with a solid magenta line to it. This throws out flight calculations such as TOD, progress ffice:smarttags" />
information etc. But what is most irritating is that if an RNAV approach was flown on the previous flight the system will command the speed assigned to the last leg of the previous flight. So on climb-out on the following flight it will command that speed when you engage VNAV - which is the wrong speed and most often way too low for climb.
In this version the VNAV issues with overspeed seem worse. The switchover logic between Mach and IAS is not seem to be working well and VNAV almost always produces overspeed on descent. We also find LVL CHG to be so erratic with autothrottle that it’s unusable.
All reported to PM support.Nic D'Alessandro
737NG builder (Hobart, Australia)
By wsixpo in forum PM Boeing FMC/CDUReplies: 4Last Post: 03-17-2010, 07:00 PM
By captdave in forum PM Boeing GCReplies: 9Last Post: 01-24-2009, 06:15 PM
By David Rogers in forum PM Boing MCPReplies: 51Last Post: 01-14-2008, 07:54 AM
By sas550 in forum PM General Q & AReplies: 13Last Post: 06-14-2007, 04:42 AM
By JAMES WEBSTER in forum PM General Q & AReplies: 2Last Post: 01-19-2006, 10:55 AM