diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_PosVelFusion.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_PosVelFusion.cpp
index 41a78c6a35..a14de0bfa8 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_PosVelFusion.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_PosVelFusion.cpp
@@ -1087,7 +1087,7 @@ void NavEKF3_core::selectHeightForFusion()
         // determine if we are above or below the height switch region
         ftype rangeMaxUse = 1e-4 * (ftype)_rng->max_distance_cm_orient(ROTATION_PITCH_270) * (ftype)frontend->_useRngSwHgt;
         bool aboveUpperSwHgt = (terrainState - stateStruct.position.z) > rangeMaxUse;
-        bool belowLowerSwHgt = (terrainState - stateStruct.position.z) < 0.7f * rangeMaxUse;
+        bool belowLowerSwHgt = ((terrainState - stateStruct.position.z) < 0.7f * rangeMaxUse) && (imuSampleTime_ms - gndHgtValidTime_ms < 1000);
 
         // If the terrain height is consistent and we are moving slowly, then it can be
         // used as a height reference in combination with a range finder