Hey, i just purchased your wonderfull plane, and i must say its awsome! great job!However, when i use autopilot for altitude, it will get to say.. fl20 which its usually set as, and then suddenly it will start to climb again, sometimes even causing a stall. Thanks againRich Scammell-Donatrix

Hi.The PMDG is modelled very closely to the real 737NG autopilot and it behaves quite differently from the standard autopilot in the default FS aircrafts.If you want the airplane to HOLD a selected and already reached altitude, just engage one of the two APs in CMD mode and select ALTITUDE in the MCP (the control panel under the glareshield). If you want to climb to or descend to another altitude, first select the new altitude in the MCP (note that the airplane will hold the previously selected altitude) then prsso VS and select a + or - VS that you wish to get or press FL CH (FL change).You should use the autothrottle too, it will try to maintain the speed selected in the MCP or the one pertinent to the current stage of flight as prescribed by the FMC (if VNAV is engaged).Hope this helps.