3 hours ago, Paladin2005 said:

Very interesting, thank you somiller.

I also found a difference to my approach: My target alt in the autopilot was 4000 ft @ Unser. You have set directly to 2400 ft, so the aircraft descents further at UNSER.

Once you hit the approach button  and   you are on the glide slope, it follows the GS no matter what the alt knob is set to, in fact that is normally then set to the missed approach altitude. 

8 hours ago, Paladin2005 said:

Very interesting, thank you somiller.

I also found a difference to my approach: My target alt in the autopilot was 4000 ft @ Unser. You have set directly to 2400 ft, so the aircraft descents further at UNSER.

Yes indeed, and as far as I have deduced from watching Emanuel's (the IRL 737 pilot) videos you should set alt to FAF altitude, not IAF altitude. It just so happens that for this approach the LOC and GS are detected as far back as before UNSER, so in this case, as long as you select LOC and then APPR on the MCP before UNSER and assuming both become active the GS should take you down even with the alt set at 4000. I haven't tried it, but I'd be willing to bet on it.

9 hours ago, Bobsk8 said:

Once you hit the approach button  and   you are on the glide slope, it follows the GS no matter what the alt knob is set to, in fact that is normally then set to the missed approach altitude. 

Bob,

Great point, and I hadn't considered that...indeed makes sense to set to missed approach alt after GS has been captured.

I flew the approach leaving ALT at 4000 and once GS was live I activated APPR and GS captured and flew all the way down...I suspect the OP didn't activate APPR until after passing UNSER, and then it's too late, you're already well above GS - unless you disable the AP, descend below GS and then engage AP to capture GS from below. I flew this approach a dozen times in the PMDG B738 and never had it NOT capture and fly the GS all the way to touchdown, no matter what I had set in the ALT window.