diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
index e0ec550bac..464d6896f0 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
@@ -277,6 +277,7 @@ void NavEKF3_core::InitialiseVariables()
     gpsPosAccuracy = 0.0f;
     gpsHgtAccuracy = 0.0f;
     baroHgtOffset = 0.0f;
+    rngOnGnd = 0.05f;
     yawResetAngle = 0.0f;
     lastYawReset_ms = 0;
     tiltErrorVariance = sq(M_2PI);