There are two conditions triggering failsafe mode. The conditions are as follows:

1. Connection between the onboard computer and the flight controller is lost (loss of offboard connection)

2. Telemetry connection between the drone and the Ground station is lost (loss of MQTT connection)

loss of offboard connection is more dangerous than loss of MQTT connection, because in the case of loosing offboard connection we do not have a computer on the drone to run our emergency code. Therefore, the safest and only decision we can make is to land the drone. We should keep in mind that landing on slopes may be challenging for the drone losing its onboard computer.

The frequency of loosing offboard connection is so rare because it uses cable connection. But the frequency of loosing MQTT connection is often because the connection protocol is WiFi.

Type of connection loss	Cause	Frequency	Measure	Challenge of Measure
loss of offboard	loss of cable connection	rarely	landing immediately	landing on slopes
loss of MQTT	loss of WiFi connection	often	triggering return home after a few seconds	not knowing altitude of other drones