Yesterday I was set up for an land 3 approach to EKCH, LAND 3 was annunciated, then about 1000ft AGL autopilot disengaged. I tried to figure out why it did it but im not sure. Could someone tell me the criteria for LAND 3 disconnect on fail op 738? Does it disconnect if I inadverently push the trim knob (I have set my elevator trim up&down to buttons on my flight sim yoke)? Im not sure if I maybe accidentaly pressed one of these.

 

One thing I was considering is the turbulence effect. I have AS2012 and no turbulence supression on anywhere (FSUIPC, FSX menu or fsx.cfg) as I have never had problems before with S-turn issues. Is there anyone else flying with AS2012 and latest FSUIPC reg version? Do you have any problems with autopilot and turbulence? I know that the major problem should be the s-turn issue (with ASE at least) but is the autopilot disconnecting during turbulence also a known issue regardin ngx? I havent found posts on that..

 

Thanks!

Does it disconnect if I inadverently push the trim knob

 

Yes.

 

Could someone tell me the criteria for LAND 3 disconnect on fail op 738?

 

Search FCOM vol.2 "autopilot disengagement".

 

but is the autopilot disconnecting during turbulence also a known issue regardin ngx?

 

A week or two ago we've got such topic here.

http://forum.avsim.net/topic/379365-land3-disconnects-before-flare-on-heavy-windshearcrosswind/#entry2417614

 

and http://forum.avsim.net/topic/379365-land3-disconnects-before-flare-on-heavy-windshearcrosswind/#entry2418384

 

On a second read I think my answers are a little convoluted and excessive but this may shed some light on your question.

 

In your case It was most likely bumping the trim button. I've been guilty of that scenario a few time meself :).