diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_VehicleStatus.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_VehicleStatus.cpp
index 2eaaa535bd..de9bb75884 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_VehicleStatus.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_VehicleStatus.cpp
@@ -470,7 +470,6 @@ void NavEKF3_core::setTouchdownExpected(bool val)
 // enabled by the combination of EK3_RNG_USE_HGT and EK3_RNG_USE_SPD parameters.
 void NavEKF3_core::setTerrainHgtStable(bool val)
 {
-    terrainHgtStableSet_ms = imuSampleTime_ms;
     terrainHgtStable = val;
 }
 
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
index b401a340cc..dacb866561 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
@@ -225,7 +225,6 @@ void NavEKF3_core::InitialiseVariables()
     lastVelReset_ms = 0;
     lastPosResetD_ms = 0;
     lastRngMeasTime_ms = 0;
-    terrainHgtStableSet_ms = 0;
 
     // initialise other variables
     gpsNoiseScaler = 1.0f;
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.h b/libraries/AP_NavEKF3/AP_NavEKF3_core.h
index 4c6e554fed..31a07a433b 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.h
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.h
@@ -1238,7 +1238,6 @@ private:
     uint32_t lastRngMeasTime_ms;            // Timestamp of last range measurement
     uint8_t rngMeasIndex[2];                // Current range measurement ringbuffer index for dual range sensors
     bool terrainHgtStable;                  // true when the terrain height is stable enough to be used as a height reference
-    uint32_t terrainHgtStableSet_ms;        // system time at which terrainHgtStable was set
 
     // body frame odometry fusion
     obs_ring_buffer_t<vel_odm_elements> storedBodyOdm;    // body velocity data buffer