Precision landing can no longer see its target

What ArduPilot says:

• PrecLand: Target Lost

Precision landing steers the landing onto a target seen by a sensor: an infrared beacon, or a camera whose computer sends LANDING_TARGET messages. The sensor has reported no target for 2 s. A copter goes on straight down for PLND_TIMEOUT seconds (4 by default); if the target is still not seen, PLND_STRICT decides: 0 keep landing straight down, 1 climb back and try again, up to PLND_RET_MAX times, 2 the same, and hover without landing once the tries are used up. Trying again needs a rangefinder height between PLND_ALT_MIN and PLND_ALT_MAX.

What to do, most likely first

1. The target left the sensor's view: the aircraft drifted or tilted in the wind, or came so low that the target no longer fits in the picture.

   CheckIn the log, see at what height the target was lost and how far the aircraft was from it.

   FixMake the target visible to the end: a larger marker or beacon, or a small marker inside a large one for the last metres. Do not rely on precision landing in strong wind.

2. The sensor could not see well: sunlight on an infrared sensor, a dark or blurred camera picture, a dirty lens.

   FixTest the detection on the ground and in a hover at the heights of a landing, in the light you will fly in.

3. The companion computer stopped sending: its program crashed, or its link to the flight controller dropped.

   CheckThe LANDING_TARGET messages stop at that moment and never come back.

   FixFix the program or the wiring and test on the bench (props off) before flying again.

Parameters to look at