Just wondering whether anyone has struck this problem with the 737-800.It's never happened to me before and I'm wondering what the cause is.When climbing through about 7000ft vnav suddenly disengages and speed comes up on the mcp.At the same time a cws p sign appears in the efis, sometimes followed by cws r.The aircraft then climbs for a while before descending rapidly.After I re-engage v nav the aircraft will recommence climbing in this mode for a few minutes before once again disengaging, reverting to speed and descending.Does anyone know just what's going on?Until now v nav has worked perfectly for me and I can't understand why this problem has just appeared out of left field as I certainly haven't changed any of my operating procedures.One other question: why are the flaps fully down when the 737-800 is first selected in FS9.I don't recall this happening with the 737-700.Frank

Hello Frank, Yes the AFS is reverting to CWS because it thinks you want control, and how does it know this? Because if one *touches* in anyway the flight controls while the AFS is in control you are telling it "I got the aircraft". So if you desire the AFS to be in control do not touch the yoke. Works this way even in a cessna, one simply does not take control without stating your intentions "I got the aircraft" to the other pilot and touching the controls even bumping it either in pitch and roll is asking on a NG ;-). Not sure why the flaps are deployed on startup, I would remove any FLT saved files in the C:Documents and SettingscrvmMy DocumentsFlight Simulator Files and then check. [h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/forum/betaimg.jpgAMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | WD SATA 80 GIG | 512 DDR 400 |

Many thanks Randy for your very prompt response.I'll follow your advice and see what happens.Frank.

Randy,Unfortunately the problem persists.I have not touched the controls while the afs is in control.I have used the 737-600/700 from day one and v nav has never been a problem.It only became an issue recently, shortly after I started using the 800/900.It is perplexing and frustrating and I would welcome some suggestions for a solution.As said earlier this problem has come right out of left field.V nav operated perfectly until yesterday when it started behaving erratically.I have not changed any settings or operating procedures.It is a complete mystery.I have uninstalled/reinstalled the PMDG package but the problem is still there.Hope you can help.

Can anyone help please?This problem is sending me crazy!

Frank please take me step by step What else if anything you run with FSAre you loading a saved flight or built a new oneWhat routewhat weightwhat you engage when you engage itscreenshot the moment the A/P disconnectsEtc etc this way we can narrow it down and figure out what is going on there.[h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/forum/betaimg.jpgAMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | WD SATA 80 GIG | 512 DDR 400 |

Randy,I think I've resolved the problem.I think it was caused by conflicting fuel measurement units.The load manager was reading the fuel in lbs while the FS9 fuel loading system, which was I was using to adjust fuel loads, was reading in kgs.Even when I change the load manager to kgs it seems to default to lbs after each flight.Is there a reason for this?Also, is it possible to change the FS9 fuel measurement units to lbs?Anyway a couple of flights today went without a hitch and v nav worked perfectly.Many thanks for your help so far.