Turn off the RC controller and unplug the battery of the drone.
When you are flying with the GPS...
Remember that the GPS is not perfect, it has an error of ~5 meters.
When flying near buildings the error of the GPS may increase due to signal reflections.
To work properly it needs direct line of sight of at least 6 satellites and the HDOP must be under 2.0 (APM gives you this information).
The drone will not avoid obstacles on its own unless it has been programmed for
it. As the operator, it is your job to recognize and avoid obstructions while flying.
Erle-Copter requires an active GPS signal before takeoff. If Erle-Copter loses GPS signal in flight, it will trigger a GPS failsafe indicated with a high-high-high-low tone, and automatically switch to manual control (standard - altitude hold mode). Always be prepared to regain manual control of Erle-Copter at any time while flying and choose an unobstructed flying area to improve GPS signal strength. When flying a mission, we recommended changing the GPS failsafe behavior to land.
More about safety...
You might want to configure the "EStop Switch". This turns off the motors immediately but please be careful with it when you are in flight. Use the EStop Switch just in case somebody can be hurt.
Do not charge near flammables/explosive substances.
Don’t charge LiPos unattended.
Double check that the settings for the lithium polymer charger are correct for the pack being charged. This includes the cell count, as well as the current settings. In general, most lithium polymer batteries should be charged to no more than 4.2 volts per cell or depleted to less than 3.0 volts per cell.