diff --git a/libraries/AP_NavEKF/AP_NavEKF.cpp b/libraries/AP_NavEKF/AP_NavEKF.cpp
index 2a9d38b42e..9217bc4ae6 100644
--- a/libraries/AP_NavEKF/AP_NavEKF.cpp
+++ b/libraries/AP_NavEKF/AP_NavEKF.cpp
@@ -4340,21 +4340,21 @@ void NavEKF::ZeroVariables()
     lastHealthyMagTime_ms = imuSampleTime_ms;
     TASmsecPrev = imuSampleTime_ms;
     BETAmsecPrev = imuSampleTime_ms;
-    lastMagUpdate = imuSampleTime_ms;
+    lastMagUpdate = 0;
     lastHgtMeasTime = imuSampleTime_ms;
-    lastHgtTime_ms = imuSampleTime_ms;
-    lastAirspeedUpdate = imuSampleTime_ms;
+    lastHgtTime_ms = 0;
+    lastAirspeedUpdate = 0;
     velFailTime = imuSampleTime_ms;
     posFailTime = imuSampleTime_ms;
     hgtFailTime = imuSampleTime_ms;
     tasFailTime = imuSampleTime_ms;
     lastStateStoreTime_ms = imuSampleTime_ms;
-    lastFixTime_ms = imuSampleTime_ms;
-    secondLastFixTime_ms = imuSampleTime_ms;
+    lastFixTime_ms = 0;
+    secondLastFixTime_ms = 0;
     lastDecayTime_ms = imuSampleTime_ms;
     timeAtLastAuxEKF_ms = imuSampleTime_ms;
     flowValidMeaTime_ms = imuSampleTime_ms;
-    flowMeaTime_ms = imuSampleTime_ms;
+    flowMeaTime_ms = 0;
     prevFlowFusionTime_ms = imuSampleTime_ms;
     rngMeaTime_ms = imuSampleTime_ms;
     ekfStartTime_ms = imuSampleTime_ms;