diff --git a/src/xswiftbus/terrainprobe.cpp b/src/xswiftbus/terrainprobe.cpp
index fc0fa227b..baee8a3db 100644
--- a/src/xswiftbus/terrainprobe.cpp
+++ b/src/xswiftbus/terrainprobe.cpp
@@ -7,6 +7,7 @@
  */
 
 #include "terrainprobe.h"
+#include "utils.h"
 #include <XPLM/XPLMGraphics.h>
 #include <limits>
 
@@ -16,7 +17,7 @@ namespace XSwiftBus
 
     CTerrainProbe::~CTerrainProbe() { XPLMDestroyProbe(m_ref); }
 
-    double CTerrainProbe::getElevation(double degreesLatitude, double degreesLongitude, double metersAltitude) const
+    double CTerrainProbe::getElevation(double degreesLatitude, double degreesLongitude, double metersAltitude, const std::string &callsign) const
     {
         double x, y, z;
         XPLMWorldToLocal(degreesLatitude, degreesLongitude, metersAltitude, &x, &y, &z);
@@ -26,8 +27,18 @@ namespace XSwiftBus
         auto result = XPLMProbeTerrainXYZ(m_ref, static_cast<float>(x), static_cast<float>(y), static_cast<float>(z), &probe);
         if (result != xplm_ProbeHitTerrain)
         {
+            std::string error;
+            if (result == xplm_ProbeError) { error = "probe error"; }
+            else if (result == xplm_ProbeMissed) { error = "probe missed"; }
+            else { error = "unknown probe result"; }
+            WARNING_LOG(callsign + " " + error + " at " + std::to_string(degreesLatitude) + ", " + std::to_string(degreesLongitude) + ", " + std::to_string(metersAltitude));
+
             return std::numeric_limits<double>::quiet_NaN();
         }
+        if (probe.is_wet)
+        {
+            DEBUG_LOG(callsign + " probe hit water at " + std::to_string(degreesLatitude) + ", " + std::to_string(degreesLongitude) + ", " + std::to_string(metersAltitude));
+        }
 
         XPLMLocalToWorld(probe.locationX, probe.locationY, probe.locationZ, &degreesLatitude, &degreesLongitude, &metersAltitude);
         return metersAltitude;
diff --git a/src/xswiftbus/terrainprobe.h b/src/xswiftbus/terrainprobe.h
index 4ade3641c..55c301077 100644
--- a/src/xswiftbus/terrainprobe.h
+++ b/src/xswiftbus/terrainprobe.h
@@ -10,6 +10,7 @@
 #define BLACKSIM_XSWIFTBUS_ELEVATIONPROVIDER_H
 
 #include <XPLM/XPLMScenery.h>
+#include <string>
 
 namespace XSwiftBus
 {
@@ -34,7 +35,7 @@ namespace XSwiftBus
         //! Get the elevation in meters at the given point in OpenGL space.
         //! \note Due to the Earth's curvature, the OpenGL vertical axis may not be exactly perpendicular to the surface of the geoid.
         //! \return NaN if no ground was detected.
-        double getElevation(double degreesLatitude, double degreesLongitude, double metersAltitude) const;
+        double getElevation(double degreesLatitude, double degreesLongitude, double metersAltitude, const std::string &callsign) const;
 
     private:
         XPLMProbeRef m_ref = nullptr;
diff --git a/src/xswiftbus/traffic.cpp b/src/xswiftbus/traffic.cpp
index 7a80891e4..e6c0856fa 100644
--- a/src/xswiftbus/traffic.cpp
+++ b/src/xswiftbus/traffic.cpp
@@ -509,7 +509,7 @@ namespace XSwiftBus
 
             const double latDeg = plane->position.lat;
             const double lonDeg = plane->position.lon;
-            double groundElevation = plane->terrainProbe.getElevation(latDeg, lonDeg, plane->position.elevation);
+            double groundElevation = plane->terrainProbe.getElevation(latDeg, lonDeg, plane->position.elevation, requestedCallsign);
             if (std::isnan(groundElevation)) { groundElevation = 0.0; }
             double fudgeFactor = 3.0;
             bool hasOffset = XPMPGetVerticalOffset(plane->id, &fudgeFactor);
@@ -528,11 +528,11 @@ namespace XSwiftBus
         if (planeIt != m_planesByCallsign.end())
         {
             const Plane *plane = planeIt->second;
-            return plane->terrainProbe.getElevation(latitudeDeg, longitudeDeg, altitudeMeters);
+            return plane->terrainProbe.getElevation(latitudeDeg, longitudeDeg, altitudeMeters, callsign);
         }
         else
         {
-            return m_terrainProbe.getElevation(latitudeDeg, longitudeDeg, altitudeMeters);
+            return m_terrainProbe.getElevation(latitudeDeg, longitudeDeg, altitudeMeters, callsign + " (plane not found)");
         }
     }