Since a lot of people have issue in RC/AC transmission range, I wonder auto-pilot will work if AC and RC lose connection due to whatever reason. Will AC still be able to complete flight when RC transmission is lost?

Are you talking about Hangar's 'Autopilot' app? If so, then if LCMC in Waypoint mode is set, then no AC to RC connection is required.

Hmm. I am an android guy. What about Litchi?
The reason for asking is that, I don't believe AC would have any build-in memory for storing flight plan.

DTK Posted at 2017-12-29 02:55
Hmm. I am an android guy. What about Litchi?
The reason for asking is that, I don't believe AC would have any build-in memory for storing flight plan.

From Litchi’s homepage:
Place multiple waypoints on a map however far you want and the aircraft will fly from waypoint to waypoint and complete the mission even if the signal is lost.