You can use Level Horizon Calibration to compensate for small miss-alignments in controller orientation and to level the horizon in the QGroundControl flight view (blue on top and green on bottom).
Leveling the horizon is highly recommended, and will result in the best flight performance. This process can also be repeated if you notice a constant drift during flight.
To level the horizon:
- Start QGroundControl and connect the vehicle.
- Select the Gear icon (Vehicle Setup) in the top toolbar and then Sensors in the sidebar.
- Click the Level Horizon button.
You should already have set the Autopilot Orientation. If not, you can also set it here.
- Place the vehicle in its level flight orientation on a level surface:
- For planes this is the position during level flight (planes tend to have their wings slightly pitched up!)
- For copters this is the hover position.
- Press OK to start the calibration process.
- Wait until the calibration process is finished.
After the orientation is set and level-horizon calibration is complete, check in the flight view that the heading in the compass shows a value around 0 when you point the vehicle towards north and that the horizon is level (blue on top and green on bottom).