Question about the autopilot

[Guest Ken_Salter]

I setup a flight from KMIA to KSFO. Here are a couple of shots halfway through the flight:http://forums.avsim.net/user_files/55598.jpghttp://forums.avsim.net/user_files/55599.jpgAs you can see the plane is quite a bit off the indicated flight path. It has been on LNAV/VNAV. Flight plan was built by FSBuild for both PMDG and MSFS.My question is why it is off like this?Thanks,

[Guest falcon99]

Hi Ken,This is a known behavior. I looked through my testing notes but was unable to locate the specifics. Simply put, the algorithm needed for drawing a path vs. the algorithm utilized by the autopilot flying a path are slightly different (something to do with 'Great Circle' calculations). The differences become more magnified the longer the flight plan leg. There have been a few other messages on the forum that discuss the issue in further detail (I believe Randy answered one pretty well).Georgehttp://www.precisionmanuals.com/images/betaimg.jpg