diff --git a/libraries/AP_NavEKF2/AP_NavEKF2_core.cpp b/libraries/AP_NavEKF2/AP_NavEKF2_core.cpp
index e53d9cc9d8..d04b0f5313 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2_core.cpp
+++ b/libraries/AP_NavEKF2/AP_NavEKF2_core.cpp
@@ -194,6 +194,7 @@ void NavEKF2_core::InitialiseVariables()
     gpsPosAccuracy = 0.0f;
     gpsHgtAccuracy = 0.0f;
     baroHgtOffset = 0.0f;
+    rngOnGnd = 0.05f;
     yawResetAngle = 0.0f;
     lastYawReset_ms = 0;
     tiltErrFilt = 1.0f;