VNAV/LNAV won't arm prior to take-off

[fsgeek 0]

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.

[W1ll 0]

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.

[Mattias Nordin 23]

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

[Mattias Nordin 23]

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

[fsgeek 0]

OK cheers guys that's a great help :)

[Gramps ZA 0]

Ensure flight directors on then they will arm.