Motor interlock disabled and motors disarmed while in-flight


We had an incident this morning that I think may be an ArduCopter bug. Sequence of events:

  1. Drone goes out and completes a regular spray mission.
  2. After returning to home and almost landing, the pilots switched the drone into guided mode after the LAND_COMPLETE_MAYBE event fired.
  3. Drone climbs back to 5m (as commanded by GCS).
  4. LAND_COMPLETE fires when the drone is 5m in the air, leading to motors disarming and a hard landing.

@rmackay9 is there some known issue where guided mode should not be entered when the drone is in LAND_COMPLETE_MAYBE state?


Perhaps it wasn’t directly related to Guided mode and it just met the conditions for Land detection when the Throttle out dropped?

Vehicle was force-disarmed mid-air by mavlink command.

2021-09-03 23:56:24.596 MAVC {TimeUS : 585514887, TS : 1, TC : 1, Fr : 3,
Cmd : 400, Cur : 0, AC : 0, P1 : 0.0, P2 : 21196.0, P3 : 0.0, P4 : 0.0, X
: 0, Y : 0, Z : 0.0, Res : 0, WL : 1}

You are also running custom firmware. We don’t know what effects that
might have.

Ah, good catch. Thank you.