The drone’s default fail-safe configuration is optimized for close-range manual flight in open areas with strong GPS signal. For flying in areas with weak GPS signal or for flying missions, we recommend changing the following fail-safe settings for improved fault tolerance.

Flying in Areas with Low GPS Signal

Some flying areas have weak GPS signal strength due to physical obstructions or lack of available satellites. (If you receive a pre-arm check failure for lack of GPS 3D lock on your ground station, it is likely that you are flying in an area with low GPS signal.) To fly without GPS lock, change the fail-safe configuration to disable the horizontal geofence. This removes the system requirement for GPS lock prior to takeoff and disables all GPS-dependent flight modes, allowing you to fly only using manual control (standard – altitude-hold mode).
To Disable the Range Failsafe (Horizontal Geofence):
Connect the drone to Mission Planner. Select Config/Tuning and Standard Params. This display shows the most frequently used ArduCopter parameters for easy access.
Locate the Fence Type parameter; it is set to Altitude and Circle by default. Switch to Altitude to disable the range fail-safe, and select Write Params to save the changes to the drone.
Flying with Low GPS Signal:
Prior to takeoff, the status LED blinks blue when ready to arm without GPS lock. The drone can fly without GPS lock only in standard mode (altitude hold). If you do not have GPS lock prior to takeoff, do not activate Loiter, RTL, Follow Me, or Auto modes.

Flight Mode GPS Requirements

ModeGPS Requirement
Standard (altitude hold mode)No GPS lock required
LoiterGPS lock required
AutoGPS lock required before takeoff
RTLGPS lock required before takeoff
LandNo GPS lock required
Follow MeGPS lock required

Flying Missions with Extended Range

If you plan to fly a mission that exceeds the default range limit of 300 m, follow the preceding instructions to disable the horizontal geofence. This allows the drone to travel farther than 300 m from the launch point during the mission without triggering an RTL.
To fly a mission, the drone requires GPS lock prior to takeoff. If GPS signal is lost during the mission, the drone will trigger the default GPS failsafe behavior. If this happens, switch to manual control (standard – altitude hold mode). When flying a mission with extended range, we recommend changing the GPS fail-safe behavior to land when GPS signal is lost, improving the chances of safe recovery at greater distances.
To Configure GPS Failsafe Behavior:
Connect the drone to Mission Planner. Select Config/Tuning and Standard Params.
Locate the GPS Failsafe Enable parameter; it is set to AltHold by default. Switch to Land to assign the drone to land at the current position in the event of a loss of GPS signal, and select Write Params to save the changes to the drone.