Hi guys,I'm having some trouble arming the autopilot before take-off. Sometimes LNAV/VNAV arms and other times it doesn't. This seems to happen if I'm flying two legs in a row without exiting the flight. Any ideas?Cheers.

I can't remember exactly but I seem to recall that there's something concerning the angle between the track to the first way-point and the runway heading. If that angle is too large LNAV won't arm on the ground. Hopefully someone else can expand on this.

Make sure your first waypoint is within 5 degrees of your runway heading or the Lnav won't arm.

I also think you have to switch the flight directors off and then back on if you're flying multiple legs.

OK cheers guys that's a great help :)

Ensure flight directors on then they will arm.