A failsafe came while on the ground: the motors were stopped

A radio, battery or ground-station failsafe triggered while the copter took itself to be on the ground, so it disarmed instead of flying anywhere. “On the ground” means: the landing detector says landed; or the mode is Stabilize or Acro and the throttle stick is at zero; or, in Auto, the mission has not started. The usual case is harmless: the transmitter was switched off before disarming.

What to do, most likely first

1. The transmitter was switched off, or the ground station closed, while the copter was still armed on the ground.

   FixNothing is wrong. Disarm first, then switch the transmitter off.

2. The battery reached its failsafe level before take-off or right after landing.

   CheckThe line “Battery 1 is low …” that comes with it gives the voltage; compare it with BATT_LOW_VOLT.

   FixCharge the battery; a pack that reaches the low level on the ground cannot carry a flight.

3. In Stabilize or Acro the throttle stick was at zero in the air when the link dropped: the copter disarmed and fell.

   CheckIn the log the altitude is well above zero at the moment of the message, and the throttle input had been at its minimum for more than 0.4 s.

   FixDo not hold the throttle at zero in flight in Stabilize or Acro. Descend in AltHold or Loiter, where a low stick is a descent command and never a motor stop.

Parameters to look at

Where to do it:Failsafe ExplainerSetup & Tuning Guide