I am in need of information on a continuing problem with the PMDG 737 autopilot for some time now. 

 

First of all, it doesn’t happen on every flight and it doesn’t happen in all takeoffs and approaches.  It only happens during my takeoff from (KSFO) San Francisco International to (KSNS) Salinas Airport. 

 

I program the FMC no different than I do for any of the other flights from and to other airports.  When taking off and reaching over 500 feet the autopilot will NOT engage.  It won’t engage until it reaches 7000 feet or above and past three waypoints from the airport.  Upon approach to Salinas the autopilot uses only one channel and will NOT engage Command B even while using the Nav 1 and 2 frequencies and the correct entries for the TDZ and length of the airport or elevation.  Then when I reach the decision height the autopilot disengages on its own. The FMC setting is NOT configured for it, yet it still disengages. 

 

Has anyone experienced this and is there a step that I’m missing, or solution to this problem?  The aircraft ends up crashing to the ground not giving me sufficient time to recover thereby ruining the whole experience.  Please help!

That is a pretty short trip..., what is the flightplan that you load into the FMS?  Which runway are you departing KSFO?  Are you using FS2Crew?

 

No need to crash, if the A/P is absent without leave then fly the airplane.

In order to engage, there must be no input (pitch/roll) on the control column... And if there is excessive control column input with a/p engaged, it will drop off (into cws I think?).

 

For multi a/p Autoland, the second a/p should be selected before descending past 1500ft

That is a pretty short trip..., what is the flightplan that you load into the FMS?  Which runway are you departing KSFO?  Are you using FS2Crew?

 

No need to crash, if the A/P is absent without leave then fly the airplane.

 

 

The following is the flight plan entered:

 

DEPARTURE: KSFO RWY28R

 

WAYPOINTS:  TUYUS, WATAP, SENZY, KYNNG, BSR, JECCO, IVUVY, UGTAC, RWY31, MARNA, MARNA-HOLD

 

The decision height is my fault since I leave it at 200ft.  I should set it for 400ft which would give me suffient time to grab the aircraft and land it manually.  But the issue with A/P going off, it's still ongoing.  Also, to answer your question if I'm using FS2Crew.  "No", I'm not using any addon on FSX.

 

 

In order to engage, there must be no input (pitch/roll) on the control column... And if there is excessive control column input with a/p engaged, it will drop off (into cws I think?).

 

For multi a/p Autoland, the second a/p should be selected before descending past 1500ft

 

During final approach there is no pitch/roll on the control column.  i suspected the same as you, but that's not the case here.

 

 

The decision height is my fault since I leave it at 200ft.  I should set it for 400ft which would give me suffient time to grab the aircraft and land it manually.

 

This seems to be one of those common simisms that just won't go away. These concepts are entirely separate. The MINS for a particular approach will always be mins for that particular approach. ILS is usually about 200' AGL, sure, but that does not mean that it's the point where you should take control of the aircraft. That's rather late, actually, as you should get a feel for the controls much sooner than that.

 

-If you're flying an instrument approach, set the MINS for that approach. If you're visual, then you can leave those out entirely (even if you're using instrument guidance to back you up in getting to the runway).

-Kick the AP off as soon as you're comfortable doing so, but as early as possible so that you can get a feel for how the aircraft is handling.

 

 

 

But the issue with A/P going off, it's still ongoing.  Also, to answer your question if I'm using FS2Crew.  "No", I'm not using any addon on FSX.

 

Sounds a lot like you have a hardware trim axis that isn't set to neutral.