diff --git a/libraries/AP_NavEKF2/AP_NavEKF2_Control.cpp b/libraries/AP_NavEKF2/AP_NavEKF2_Control.cpp
index 651cb93045..ab464d97ae 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2_Control.cpp
+++ b/libraries/AP_NavEKF2/AP_NavEKF2_Control.cpp
@@ -209,14 +209,17 @@ void NavEKF2_core::setAidingMode()
         bool posUsed = (imuSampleTime_ms - lastPosPassTime_ms <= minTestTime_ms);
         bool gpsVelUsed = (imuSampleTime_ms - lastVelPassTime_ms <= minTestTime_ms);
 
+        // Check if external nav is being used
+        bool extNavUsed = (imuSampleTime_ms - lastExtNavPassTime_ms <= minTestTime_ms);
+
         // Check if attitude drift has been constrained by a measurement source
-        bool attAiding = posUsed || gpsVelUsed || optFlowUsed || airSpdUsed || rngBcnUsed;
+        bool attAiding = posUsed || gpsVelUsed || optFlowUsed || airSpdUsed || rngBcnUsed || extNavUsed;
 
         // check if velocity drift has been constrained by a measurement source
         bool velAiding = gpsVelUsed || airSpdUsed || optFlowUsed;
 
         // check if position drift has been constrained by a measurement source
-        bool posAiding = posUsed || rngBcnUsed;
+        bool posAiding = posUsed || rngBcnUsed || extNavUsed;
 
         // Check if the loss of attitude aiding has become critical
         bool attAidLossCritical = false;
@@ -225,6 +228,7 @@ void NavEKF2_core::setAidingMode()
                    (imuSampleTime_ms - lastTasPassTime_ms > frontend->tiltDriftTimeMax_ms) &&
                    (imuSampleTime_ms - lastRngBcnPassTime_ms > frontend->tiltDriftTimeMax_ms) &&
                    (imuSampleTime_ms - lastPosPassTime_ms > frontend->tiltDriftTimeMax_ms) &&
+                   (imuSampleTime_ms - lastExtNavPassTime_ms > frontend->tiltDriftTimeMax_ms) &&
                    (imuSampleTime_ms - lastVelPassTime_ms > frontend->tiltDriftTimeMax_ms);
         }
 
@@ -239,9 +243,11 @@ void NavEKF2_core::setAidingMode()
                 maxLossTime_ms = frontend->posRetryTimeUseVel_ms;
             }
             posAidLossCritical = (imuSampleTime_ms - lastRngBcnPassTime_ms > maxLossTime_ms) &&
-                   (imuSampleTime_ms - lastPosPassTime_ms > maxLossTime_ms);
+                                 (imuSampleTime_ms - lastExtNavPassTime_ms > maxLossTime_ms) &&
+                                 (imuSampleTime_ms - lastPosPassTime_ms > maxLossTime_ms);
             posAidLossPending = (imuSampleTime_ms - lastRngBcnPassTime_ms > (uint32_t)frontend->_gsfResetDelay) &&
-                    (imuSampleTime_ms - lastPosPassTime_ms > (uint32_t)frontend->_gsfResetDelay);
+                                (imuSampleTime_ms - lastExtNavPassTime_ms > (uint32_t)frontend->_gsfResetDelay) &&
+                                (imuSampleTime_ms - lastPosPassTime_ms > (uint32_t)frontend->_gsfResetDelay);
         }
 
         if (attAidLossCritical) {
@@ -335,6 +341,7 @@ void NavEKF2_core::setAidingMode()
             lastPosPassTime_ms = imuSampleTime_ms;
             lastVelPassTime_ms = imuSampleTime_ms;
             lastRngBcnPassTime_ms = imuSampleTime_ms;
+            lastExtNavPassTime_ms = imuSampleTime_ms;
             }
             break;
         }
diff --git a/libraries/AP_NavEKF2/AP_NavEKF2_core.h b/libraries/AP_NavEKF2/AP_NavEKF2_core.h
index ecb100e9cd..d8e3886d46 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2_core.h
+++ b/libraries/AP_NavEKF2/AP_NavEKF2_core.h
@@ -1160,6 +1160,7 @@ private:
     ext_nav_elements extNavDataDelayed; // External nav at the fusion time horizon
     uint32_t extNavMeasTime_ms;         // time external measurements were accepted for input to the data buffer (msec)
     uint32_t extNavLastPosResetTime_ms; // last time the external nav systen performed a position reset (msec)
+    uint32_t lastExtNavPassTime_ms;     // time stamp when external nav position measurement last passed innovation consistency check (msec)
     bool extNavDataToFuse;              // true when there is new external nav data to fuse
     bool extNavUsedForYaw;              // true when the external nav data is also being used as a yaw observation
     bool extNavUsedForPos;              // true when the external nav data is being used as a position reference.