Autopilot shutting off

[Guest vectorguy]

For some reason my autopilot on my 737-800 keeps disconnecting when level at Flight Levels. I have tried command A and B with no luck. Any advice.

[downscc 1,327]

Is there a message on the CDU? Do you hear a gong sound when it disconnects? Are you cruising above max cruise as defined on the CRZ page? Please sign your name in this forum... good luck.

[Guest vectorguy]

Yes I do hear a gong. Maybe I was pushing the max cruise M.81, but even when I slowed to M.77 I still lost autopilot until I descended with idle power. Ron ShustermanKPVD

[Guest vectorguy]

Well I just flew again and even at M.78 she dissengaged, but only after cruising at FL300 for an hour. After that hour the Auto-Pilot would not hold and the CDU displayed the disconnect. The disconnect horn would sound each and every time not the gong as I stated before.Ron

[downscc 1,327]

Ron: This is not normal, I've been flying the 737-700 for months and have never had this happen; at least you know it's not the simulation. Having not had it happen, I can't give you much help. Are you cruising with VNAV & LNAV active? Are you below the max cruise alt that's shown on the CRZ page? Does CWS become active after the AP disconnect - then maybe it's noise from your joystick. Does autothottle disconnect when AP disconnects? There's is a reason, just gotta keep at it until you find it. Good luck.

[Guest vectorguy]

Thanks Dan, I'll keep at it for awhile and try different configs.Thanks again. Ron