Hi,While flying the 737-800 from Ibiza to East Midlands this morning,at flight level 350,all of a sudden the LNav and VNav were disengaged and on the PFD were the letters CWS A and CWS B in yellow,the aircraft promptly went into a steep dive and banked severly!!This happened on sevral occasions during the flight,to rescue the situation I had to manually control the aircraft back on course and then managed to re- engage the LNav and VNav buttons.Needless to say the passengers were not happy!Any thoughts on why this is happening?I was using real world weather if that has anything to do with it.Thanks,Regards,Martin.

Using ActiveSky with "wake turbulence" option active?In that case, disable that option and all will be fine again.In case you are not using AS, then it has been a problem with your flight controls: CWS mode engages when you apply enogh input on the manual flight controls, in that case the AFDS enters the "Control Wheel Steering" mode, where it's you how command the plane.BRClaudio

Hi Thanks for the reply.I'm not using Activesky,but was using real world weather,I noticed that Lnav and Vnav disengaged when the wind changed direction,it made the aircraft unstable for some reason.Is thre anyway in FSUIPC to alter the wind effect?Thanks,Regards,Martin.

Hi MartinYes, you can smooth the wind changes in FSUIPC Just have a look at the Wind category (You need the registered version).But it could also realised something else:Have you used you Joystick? And have you touched it in cruise?If you touch it with the Autopilot on the plane goes from CMD (Autopilot) to CWS (Control Wheel Stearing). That is like in real live when, lets say the pilot tries to control the plane by himself while the Autopilot is on...Hope this helpsMartin

Hi,Turbulence is probably not the problem here. Severe turbulence would disconnect the A/P and not revert it to CWS.The most likely cause for your problem is either spikes from your joystick, which can be cured by checking "Eliminate spikes" in a registered FSUIPC or that you moved the joystick during flight as was mentioned earlier.Hope it helps,