Richard Portier wrote on Dec 19^th, 2009 at 2:07pm:

May be I'm wrong but consider the weight like a consequence not the cause. For me the problem is in amount, located in some flags... Where ? that is the question. Actually I am trying some adjustements (one by one, it's a long process) in air and cfg files parameters. I'm not a guru. I have an empiric approach. So...! Also the issue is perhaps in an other place because some pilots have this problem, some other have not !?

In their response to my ticket on this issue, CS said that I should check aircraft speed, configuration and WEIGHT. They cited these 3 factors in the context of any one of them causing the AP not to be able to capture an ILS.

I can see how SPEED, if too high, would make the AP lag behind the ILS needle indications- simply because they come and go so quickly if you are flying toward the LOC and/or GS at an excessive speed... the AP just can't make adjustments that fast. I get that. I can even understand how flaps configuration could affect the AP because you can't fly the airplane at correct approach speeds without flaps & slats. However, this is only a peripheral connection; the REAL culprit would still be SPEED, because the old Sperry AP neither "knows" nor cares how much flap you have out. If you could fly the airplane on approach at 125KIAS without flaps, the AP should be FINE with that. So "configuration" would be only an indirect factor preventing proper AP function- only because proper config enables slow-enough airspeed.

I find it difficult to believe that CS or any other sim-aircraft developer of their caliber would program in a clearly-irrelevant "weight" parameter in the AUTOPILOT operation of an airplane that has ZERO automation such as FMS. Without FMS or similar functionality, the AP simply has no way of "knowing" aircraft weight at any given point in time- so why would excessive WEIGHT play any part in causing the AP to fail to capture and fly an ILS?

I'm just baffled by CS's suggestion that I should check approach WEIGHT as a possible cause for the AP failure to capture LOC and GS.
Likewise, I'm baffled by those who said here (above somewhere) that the AP works for them on ILS's with an empty airplane but not when loaded. It's just nonsensical to me.

You might as well say that the AP in this airplane only works well if the windshield wipers are turned on. That's how absurd and irrelevant "weight" seems to me as a possible cause of AP failure.

That's why I asked for help in understanding what weight can possibly have to do with AP operation on approaches in this steam-gauge, no-FMS airplane.