diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_OptFlowFusion.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_OptFlowFusion.cpp
index fc8626a5bc..ce395b6a34 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_OptFlowFusion.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_OptFlowFusion.cpp
@@ -25,6 +25,8 @@ void NavEKF3_core::SelectFlowFusion()
         optFlowFusionDelayed = false;
     }
 
+    of_elements ofDataDelayed;      // OF data at the fusion time horizon
+
     // Check for data at the fusion time horizon
     const bool flowDataToFuse = storedOF.recall(ofDataDelayed, imuDataDelayed.time_ms);
 
@@ -47,7 +49,7 @@ void NavEKF3_core::SelectFlowFusion()
     // if have valid flow or range measurements, fuse data into a 1-state EKF to estimate terrain height
     if (((flowDataToFuse && (frontend->_flowUse == FLOW_USE_TERRAIN)) || rangeDataToFuse) && tiltOK) {
         // Estimate the terrain offset (runs a one state EKF)
-        EstimateTerrainOffset();
+        EstimateTerrainOffset(ofDataDelayed);
     }
 
     // Fuse optical flow data into the main filter
@@ -56,7 +58,7 @@ void NavEKF3_core::SelectFlowFusion()
             // Set the flow noise used by the fusion processes
             R_LOS = sq(MAX(frontend->_flowNoise, 0.05f));
             // Fuse the optical flow X and Y axis data into the main filter sequentially
-            FuseOptFlow();
+            FuseOptFlow(ofDataDelayed);
         }
     }
 }
@@ -66,7 +68,7 @@ Estimation of terrain offset using a single state EKF
 The filter can fuse motion compensated optical flow rates and range finder measurements
 Equations generated using https://github.com/PX4/ecl/tree/master/EKF/matlab/scripts/Terrain%20Estimator
 */
-void NavEKF3_core::EstimateTerrainOffset()
+void NavEKF3_core::EstimateTerrainOffset(const of_elements &ofDataDelayed)
 {
     // horizontal velocity squared
     float velHorizSq = sq(stateStruct.velocity.x) + sq(stateStruct.velocity.y);
@@ -264,7 +266,7 @@ void NavEKF3_core::EstimateTerrainOffset()
  * https://github.com/PX4/ecl/blob/master/matlab/scripts/Inertial%20Nav%20EKF/GenerateNavFilterEquations.m
  * Requires a valid terrain height estimate.
 */
-void NavEKF3_core::FuseOptFlow()
+void NavEKF3_core::FuseOptFlow(const of_elements &ofDataDelayed)
 {
     Vector24 H_LOS;
     Vector3f relVelSensor;
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.h b/libraries/AP_NavEKF3/AP_NavEKF3_core.h
index f847dbbbe5..cbdcfae2c4 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.h
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.h
@@ -795,10 +795,10 @@ private:
     void SelectBodyOdomFusion();
 
     // Estimate terrain offset using a single state EKF
-    void EstimateTerrainOffset();
+    void EstimateTerrainOffset(const of_elements &ofDataDelayed);
 
     // fuse optical flow measurements into the main filter
-    void FuseOptFlow();
+    void FuseOptFlow(const of_elements &ofDataDelayed);
 
     // Control filter mode changes
     void controlFilterModes();
@@ -1145,7 +1145,6 @@ private:
     // variables added for optical flow fusion
     EKF_obs_buffer_t<of_elements> storedOF;    // OF data buffer
     of_elements ofDataNew;          // OF data at the current time horizon
-    of_elements ofDataDelayed;      // OF data at the fusion time horizon
     bool flowDataValid;             // true while optical flow data is still fresh
     Vector2f auxFlowObsInnov;       // optical flow rate innovation from 1-state terrain offset estimator
     uint32_t flowValidMeaTime_ms;   // time stamp from latest valid flow measurement (msec)