Speed Restrictions

[Jackie 0]

Is there a reason sometimes why the PMDG 747 does not always follow the speed restrictions when I set them. It will descend correctly but it will not slow to the speed that I have entered. Any ideas on this issue. ThanksJackie Padilla

[michal 44]

Sometimes speed restrictions can't be met if aircraft is too heavy or programmed trajectory is too steep.

[Jackie 0]

thanks Michal for the infoJackie Padilla

[downscc 1,327]

There is much on the 747 VNAV descent performance in previous threads. There are those that prefer to use it all the way to the IAP but I prefer to use the MCP SPD and V/S to control the descent with VNAV providing secondary guidance and that seems to be more realistic in most cases.