737 Altitude hold

[757Pilot]

I have done a few uneventful flights with the DF737 autopilot. Recently, i was in the middle of a flight and the altitude hold just decided to quit on me ( I dont' have any failures set). The light for vertical speed and altitude hold comes on with the main autopilot light off, but when i engage the main witch for the autopilot, altitude hold disengages. I am using it with FS2002. I do have the updated version. I never had this problem before.

[koppenh]

Well, this sounds like one of those typical FS2002 autopilot problems. It seems to me that Microsoft have screwed up on the autopilot quite a lot. Since the Dreamfleet 737 had to be built around the FS2002 environment, it "inherited" quite a lot of those bugs, mainly with the autopilot. Nothing Dreamfleet can do about it.

I had a similar experience yesterday when flying the 737. First, the autopilot decided to climb straight through the flight level I set on the MCP in the ALT window. After setting a new target FL and disengaging and reengaging the AP, it continued normally.

Then I engaged VNAV while I was perfectly on course and heading in the right direction. Suddenly, the airplane turned around towards my departure airport! I disengaged the AP, turned back on course and used the "DIRECT TO" feature of the FMC to program the next waypoint (just to be sure). But it didn't help. It again turned off course. I watched it for a while, after a few seconds the autopilot thought the better of it and turned back on track.

Then I set my target altitude to FL330 on the MCP (it was also set on the CRZ page of the FMC), but the AP decided to stop climbing at FL 280. Here, reengaging the autopilot didn't help. I had to change my CRZ ALT on the FMC to FL329 and then back to FL330 to cure the problem.

A strange flight, indeed. Something had really messed up inside FS2002. BTW: Halfway through the climb, I also lost ATC. The window just didn't want to come up again. The controller asked me to acknowledge but I couldn't! A perfect radio faliure simulated here... ;-)

Bottom line: The autopilot is nothing to be trusted with FS2002, you always have to watch what it is doing, being prepared to take over if something goes wrong (as do real pilots, BTW. They never trust the autopilot blind). Do you save your flights to resume them later? I do so also, and I have the impression, that the longer you fly, the more strange effects tend to show up. Maybe it's better to start from scratch again every time instead of saving and continuing.

Regards, Michael