In the default FSX 737-800 if I want to fly with the autopilot alone (no FMC, no GPS), I can do the following on the MCP:

 

1. F/D switch ON

2. A/T = ARMED

3. SPEED = ON (with say 250 dialed in)

4. HDG SEL = ON (with say 180 dialed in)

5. ALT HLD = ON (with say 6000 dialed in)

6. CMD-A = ON

 

 

If I do the same thing in the PMDG 737 NGX, the CMD-A button just flashes on and off (does not stay enabled). What am I doing wrong? I am expecting it to maintain my speed, heading, and altitude as dialed in.

 

Thanks

This is to do with when and how you engage the AP. This plane behaves as the real one. That is to say if you are not correctly trimmed and fighting the aircraft when trying to engage the autopilot it will not have it. In the CDU you can disable realistic AP engage but I say don't. Learn to fly the plane. Tis much more fun.

 

When you have the aircraft under control after take off with no need to make movements on the yoke then press cmd a. It will work I am sure.

 

Regards.

I promise if you are on speed, on heading and on altitude (FD bars centered with 4 little squares around the center crossed pointers) and THEN engage AP-A it will engage appropriately. If you are below your MCP ALT select LVL CHG instead. Remember ALT HOLD on the MCP does exactly that- HOLDS current altitude. It is typically used when ATC asks you to stop climb or descent. You usually the dial in the new cleared level and LVL CHG to that until the descent/ascent is re-established .

 

The NGX requires you to FLY the aeroplane..... Have it ON FLIGHT-PATH before engaging AP. if not you will see it default to CWS in pitch or roll modes (whichever is not on path).

 

This is assuming you are using REALISTIC AP mode.

 

Let us know how you get on.....

Makes sense!

 

And NO I do not want to turn off realistic mode, I want to learn it the right way :) Looks like my time on the default 737 taught me bad habits...

 

I think the default Airbus321 behaves the way you mention, so I understand now.

 

Believe it or not, I am GLAD the PMDG behaves like this, it will make things much more fun and interesting.

 

Thanks

Just a small reminder that the autopilot will not engage below 400 ft AGL during takeoff.

I was at 5,000 feet :)

 

Anyway thanks guys... I took her up for another flight, got her level and straight, the AP kicked in just fine.

The one thing I discovered is that if you turn off Realistic AP mode, it will not work if you shut down the engines and restart them again.  The AP will not work even if you have the realistic mode turned off.  But if you start FSX with the 737 and everything running and ready to fly, the AP will function if you have the realistic AP mode turned off.  I found this out after several attempts.  I use GSX ground services and it requires the engines to be shut down.  Once GSX is finished,  I restart the engines.  But once in the air and at the minimum altitude,  the AP simply will not work even when I had the realistic mode turned off.

I shut down and start engines on the NGX every week.

 

If you have nothing lit up on the overhead panel at all (especially blue or yellow lights) the autopilot should be fine.

 

If there's yellow or blue stuff up there, your autopilot probably has no electrical power.

 

 

The one thing I discovered is that if you turn off Realistic AP mode, it will not work if you shut down the engines and restart them again. 

 

Did you "flush" the system by turning the flight directors off in between the flights? If not, you'll have issues.

 

Remember the key phrase here: realistic. You have to treat the plane realistically if you want it to behave realistically. I do thru flights all the time and the AP is just fine, so I'm betting you just need to flush the FDs.

I am puzzled by what you  mean "flushing" the system?   I never do "Between the flights",  When I start  up FSX,  I have the plane at the gate and shut down the engines so I can use GSX ground.

I forgot to mention I also use FSPassengers.  I am finding out in forums that it is not compatible with the PMDG 737NGX.  FS Passengers does work fine with my PMDG 777 and PMDG 747-8 in AP.

 

I made several tests.  PMDG 737 AP will work if I do everything at the runway and if I activate FSPassengers at the runway, loading passengers, etc and take off.  BUT,  if I start at the gate and activate FSPassengers,  the AP will not function when I take off..  Really strange.  I made 3 tests on each.  3 at the gate and 3 at the runway with the same start up steps.

I conducted 2 more tests with the same results.  The only difference when I did the test at the runway,  I cannot use GSX ground services.  I did one test without GSX ground services, but with FS Passengers at the gate, but I got the same results.  AP will not operate after take off.  I also try and activate it in all instances at almost 2000 feet.  I was wondering if perhaps GSX was the cause, it it is not.  It must be FS Passengers, and only when at the terminal gate, unfortunately.