Surface tracking has no rangefinder pointing that way

What ArduPilot says:

• SurfaceTracking: no upward rangefinder
• SurfaceTracking: no downward rangefinder

The surface-tracking switch (RCn_OPTION 75) chooses what the copter keeps its distance from in AltHold, Loiter and similar modes: low is the ground, middle nothing, high the ceiling. The position you chose needs a rangefinder that looks that way, and none is set up: “no downward rangefinder” for the ground (orientation 25), “no upward rangefinder” for the ceiling (orientation 24). The setting is left as it was.

What to do, most likely first

1. No rangefinder with that orientation is set up.

   CheckRead RNGFNDn_TYPE and RNGFNDn_ORIENT of every rangefinder.

   FixSet the rangefinder's RNGFNDn_ORIENT to 25 (down) or 24 (up) and its RNGFNDn_TYPE to the sensor fitted, then reboot.

2. The switch is in the ceiling position by habit, on a copter that has only a downward rangefinder.

   FixUse the low position, or set SURFTRAK_MODE and take the switch off that channel.

Parameters to look at

Where to do it:Board & Wiring Planner