diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_AirDataFusion.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_AirDataFusion.cpp
index 38508e44a9..79e18027ac 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_AirDataFusion.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_AirDataFusion.cpp
@@ -256,10 +256,6 @@ void NavEKF3_core::SelectBetaDragFusion()
             // we are required to correct only wind states
             airDataFusionWindOnly = true;
         }
-        // Fuse estimated airspeed to aid wind estimation
-        if (usingDefaultAirspeed) {
-            FuseAirspeed();
-        }
         FuseSideslip();
         prevBetaDragStep_ms = imuSampleTime_ms;
     }
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_Control.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_Control.cpp
index 0489aee688..c76d650aae 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_Control.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_Control.cpp
@@ -64,6 +64,7 @@ void NavEKF3_core::setWindMagStateLearningMode()
                                  PV_AidingMode != AID_NONE;
     if (!inhibitWindStates && !canEstimateWind) {
         inhibitWindStates = true;
+        windStateLastObsIsValid = false;
         updateStateIndexLim();
     } else if (inhibitWindStates && canEstimateWind &&
                (sq(stateStruct.velocity.x) + sq(stateStruct.velocity.y) > sq(5.0f) || dragFusionEnabled)) {
@@ -77,7 +78,7 @@ void NavEKF3_core::setWindMagStateLearningMode()
             Vector3F tempEuler;
             stateStruct.quat.to_euler(tempEuler.x, tempEuler.y, tempEuler.z);
             ftype trueAirspeedVariance;
-            const bool haveAirspeedMeasurement = usingDefaultAirspeed || (tasDataDelayed.allowFusion && (imuDataDelayed.time_ms - tasDataDelayed.time_ms < 500) && useAirspeed());
+            const bool haveAirspeedMeasurement = (tasDataDelayed.allowFusion && (imuDataDelayed.time_ms - tasDataDelayed.time_ms < 500) && useAirspeed());
             if (haveAirspeedMeasurement) {
                 trueAirspeedVariance = constrain_ftype(tasDataDelayed.tasVariance, WIND_VEL_VARIANCE_MIN, WIND_VEL_VARIANCE_MAX);
                 const ftype windSpeed =  sqrtF(sq(stateStruct.velocity.x) + sq(stateStruct.velocity.y)) - tasDataDelayed.tas;
@@ -342,6 +343,15 @@ void NavEKF3_core::setAidingMode()
             // a sensor that only observes attitude
             velAiding = posUsed || gpsVelUsed || optFlowUsed || airSpdUsed || dragUsed || rngBcnUsed || bodyOdmUsed;
 
+            // Store the last wind states whose errors were constrained by measurements
+            // This will be used to synthesise an airspeed measurement to enable dead reckoning
+            bool newWindStateIsObservable = !inhibitWindStates && (posUsed || gpsVelUsed || optFlowUsed || rngBcnUsed || bodyOdmUsed);
+            if (!inhibitWindStates && !newWindStateIsObservable && windStateIsObservable) {
+                windStateLastObs = stateStruct.wind_vel;
+                windStateLastObsIsValid = true;
+            }
+            windStateIsObservable = newWindStateIsObservable;
+
             // check if position drift has been constrained by a measurement source
             bool posAiding = posUsed || rngBcnUsed;
 
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
index 1b25e84e65..8533490443 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
@@ -861,18 +861,29 @@ void NavEKF3_core::readAirSpdData()
     // Check the buffer for measurements that have been overtaken by the fusion time horizon and need to be fused
     tasDataToFuse = storedTAS.recall(tasDataDelayed,imuDataDelayed.time_ms);
 
-    float easErrVar = sq(MAX(frontend->_easNoise, 0.5f));
-    // Allow use of a default value if enabled
-    if (!useAirspeed() &&
-        imuDataDelayed.time_ms - tasDataDelayed.time_ms > 200 &&
-        is_positive(defaultAirSpeed)) {
-        tasDataDelayed.tas = defaultAirSpeed * EAS2TAS;
-        tasDataDelayed.tasVariance = sq(MAX(defaultAirSpeedVariance, easErrVar));
-        tasDataDelayed.allowFusion = true;
-        tasDataDelayed.time_ms = 0;
-        usingDefaultAirspeed = true;
-    } else {
-        usingDefaultAirspeed = false;
+    // Allow use of a default value or a value synthesised from a stored wind velocity vector
+    if (!useAirspeed()) {
+        if (is_positive(defaultAirSpeed)) {
+            if (imuDataDelayed.time_ms - tasDataDelayed.time_ms > 200) {
+                tasDataDelayed.tas = defaultAirSpeed * EAS2TAS;
+                tasDataDelayed.tasVariance = MAX(defaultAirSpeedVariance, sq(MAX(frontend->_easNoise, 0.5f)));
+                tasDataToFuse = true;
+                tasDataDelayed.allowFusion = true;
+            } else {
+                tasDataToFuse = false;
+            }
+        } else if (windStateLastObsIsValid && !windStateIsObservable) {
+            if (imuDataDelayed.time_ms - tasDataDelayed.time_ms > 200) {
+                // use stored wind state to synthesise an airspeed measurement
+                const Vector3F windRelVel = stateStruct.velocity - Vector3F(windStateLastObs.x, windStateLastObs.y, 0.0F);
+                tasDataDelayed.tas = windRelVel.length();
+                tasDataDelayed.tasVariance = sq(MAX(frontend->_easNoise, 0.5f));
+                tasDataToFuse = true;
+                tasDataDelayed.allowFusion = true;
+            } else {
+                tasDataToFuse = false;
+            }
+        }
     }
 }
 
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
index d1b4ba86c8..f608f6d4d2 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp
@@ -268,6 +268,9 @@ void NavEKF3_core::InitialiseVariables()
     prevInFlight = false;
     manoeuvring = false;
     inhibitWindStates = true;
+    windStateLastObs.zero();
+    windStateIsObservable = false;
+    windStateLastObsIsValid = false;
     windStatesAligned = false;
     inhibitDelVelBiasStates = true;
     inhibitDelAngBiasStates = true;
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_core.h b/libraries/AP_NavEKF3/AP_NavEKF3_core.h
index 8f3fd2d057..69cbfb5acf 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_core.h
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_core.h
@@ -1110,6 +1110,9 @@ private:
     Vector3F magTestRatio;          // sum of squares of magnetometer innovations divided by fail threshold
     ftype tasTestRatio;             // sum of squares of true airspeed innovation divided by fail threshold
     bool inhibitWindStates;         // true when wind states and covariances are to remain constant
+    Vector2F windStateLastObs;      // wind states from the last time wind states were constrained using observations (m/s)
+    bool windStateLastObsIsValid;
+    bool windStateIsObservable;     // true when wind states are observable from measurements.
     bool windStatesAligned;         // true when wind states have been aligned
     bool inhibitMagStates;          // true when magnetic field states are inactive
     bool lastInhibitMagStates;      // previous inhibitMagStates
@@ -1145,7 +1148,6 @@ private:
     range_elements rangeDataDelayed;// Range finder data at the fusion time horizon
     tas_elements tasDataNew;        // TAS data at the current time horizon
     tas_elements tasDataDelayed;    // TAS data at the fusion time horizon
-    bool usingDefaultAirspeed;      // true when a default airspeed is being used instead of a measured value
     mag_elements magDataDelayed;    // Magnetometer data at the fusion time horizon
     gps_elements gpsDataNew;        // GPS data at the current time horizon
     gps_elements gpsDataDelayed;    // GPS data at the fusion time horizon