Hi, I have encountered a serious problem concerning Level-D 767 FMS.I started my flight in cold and dark. After aircraft preparation and FMC initialaization , I entered the route waypoints and selected the appropriate SID. All waypoints appeared in the ND as I expected. According to the SID ,the aircraft was to turn left after takeoff and by reaching the first waypoint of the SID , turn to right toward INTC. As you know the next step is entering ZFW and CRZ ALT.My problem started from here on.After entering the Cost Index (80), the route suddenly changed in the ND, appeared as a direct line, ignoring the first waypoint before the INTC.When I activated LNAV, VNAV and CMD after takeoff , the aircraft left the route and went toward the first SID waypoint ( the ignored one).After reaching the ignored waypoint, the aircraft turned to the INTC and followed the programed route.This has been occoured for me several times in various airports.Is there any explanation for such bizarre behavoir by the FMS?

Cost index should only change the VNAV path slightly. If you have LNAV issues your best bet is to use the official forum for registered customers.Regards