Reading telemetry from Pixhawk cube


I am trying to read the flight mode from the heartbeat messages sent out from my pixhawk cube (black) with an arduino.

Everything seems to work fine but whenever i connect the pixhawk cube to mission planner via usb, i get an additional heartbeat message that tells me the wrong flight mode and upon disconnection from mission planner this wrong heartbeat message stops sending.

May i know how i can resolve this? My pixhawk cube is running arducopter v3.6.2

Many thanks in advance!