I was begginning my flight from EGHH to LEMG (bournemouth to malaga) and i set up all my radios, flaps, my CDU and set up the auto pilot ready to take over from 1000feet. I then went 95% N1, got to 140knots and rotated. Everything normal, landing gear up and flaps to 1. I then clicked auto pilot and alt hold which was set to 8000feet. The plane plummeted to the floor and crashed. This has happened twice now Can anyone help??
Im not an expert on the 737PIC but im not sure you should press 'alt hold' as this holds the altitude you are currently at. Engage the autopilot and then V/S rather than alt hold.
Altitude changes are made with LVL CHG and not ALT HOLD. Try to locate a tutorial for PMDG and read about the MCP. It will help. FT really sucks for not printing a good manual, very unprofessional and has caused many people grief..
Make sure the vertical speed was not a negative number. If you override the setting that is default (as in you change it yourself) and you have the target altitude set higher than the current alitude but the VS (vert. speed) is a negative number, it will go down.
When you are preparing your autopilot (before takeoff) set the following
All AP switches off, only numbers to be changed
Heading: Runway heading (to find this go to the map, press on the runway)
Altitude: 8000ft (or whatever you wish)
Vertical Speed: For takeoff, about +2000ft/s -> +2300ft/s, for normal climbing (out of 10000) just leave it at +1800
I've had this happen a couple of times myself. I've found that what the altitude setting does, it seems for only some aircraft, is completely disregard the stick altogether. So if you are holding a lot of back pressure (pulling the stick back to get the plane to climb) and then you click Alt Hold, the plane would act as if you just let go of the stick altogether. It then attempts to get the Vs you set by trimming the plane. Thus the immediate effect is for your plane to dive into the ground while the autopilot slowly trims it upwards.
The solution was simple for me. Make sure you trim your plane manually for the rate of accent you want before you hit autopilot. I always trim my plane so that I can let go of the stick and get approx. the climb that I want and THEN I hit the Alt Hold button. Try that, see if it works for you.
Check you have the latest FSPUIC installed or none at all. This can sometimes cause the autopilot to behave erratically