I'm sure this has been reported before, but I can't find the topic, so here goes. On my last two flights, Lnav has become very unstable during cruise flight. It appears to chase the course and uses large bank angles to correct resulting in ever increasing deviations. I tried engaging heading select in an attempt to stabilize the aircraft and also tried reselecting the active waypoint while in Lnav, but I'm unable to correct the problem when it occurs. I'm always very close to optimum altitude, use a cruise speed of .84 mach, and all hydrraulic and flight control synoptics appear normal.Any ideas? Thanks.Pete Locascio

Do you happen to use ActiveSky?William Stroud

No, I don'tPete L.