747x pmdg

[pete_auau 1,158]

Hi all here a strange one flight from canberra to sydney under an hour flight time set the fmc etc set my crz alt to 21000 set eveything else. Took off set vnav and lnav set the auto pilot to on everything flying ok to flight plan whilst climbing set my mcp alt to fl 21000 got the 1 thousnad warning that was close to alt than noiced that the plane keep kept climbing past 21000 with mcp on 21000 fmc set to flt level20300 with vnav and lnav and auto still engaged the thrust was replaced by the speed. plane climbed to fl 26000 b4 i decided to turn off auto pilot but plane still kept climbing thru to fl 28000 b4 i got it under contol to bring it down to fl 21000. tried to use the vs option but had no effect once i got below 21000 and on correct flight plan set vnav and lnav and was fine again. Was using fscrew2 on this flight and using rex2 weather so in short the aircfrat was disreguading the auto settings and fmc on climb

[downscc 1,327]

A FMC setting of 21300 would most likely be caused by you when you dialed the MCP altitude to 21000 then overshot to 21300 and left it there for more than a second, the FMS will reset to the MCP altitude. However, a FMC altitude of 20300 is a mystery. To set things right, set both the MCP and the CDU cruise altitude to desired value.

[Cuddly1956 1]

Was the 747 very light? That's the only time I've had it overshoot the altitudes as it needs a lot of derate to be able to control it.If very light just climb using VS as it does help a lot.John Ellison

[pete_auau 1,158]

hi yes plane was light on fuel and weight thx for ur quick reply i will try ur suggestion next time :}