diff --git a/src/MissionManager/MissionController.cc b/src/MissionManager/MissionController.cc
index 5d8234ca1d8c94776169abfaa3a7b95ab4409267..b093c3f58acc82e934cbb2104249a54ee7e7dcd9 100644
--- a/src/MissionManager/MissionController.cc
+++ b/src/MissionManager/MissionController.cc
@@ -493,6 +493,7 @@ void MissionController::removeAll(void)
 {
     if (_visualItems) {
         _deinitAllVisualItems();
+        _visualItems->clearAndDeleteContents();
         _visualItems->deleteLater();
         _settingsItem = NULL;
         _visualItems = new QmlObjectListModel(this);
diff --git a/src/MissionManager/SurveyMissionItem.h b/src/MissionManager/SurveyMissionItem.h
index 315008a932d495c4fd78ba477f7bce75bf264e72..d2096ea1fe2d3a86b4bbacd0c3e575ca05d15492 100644
--- a/src/MissionManager/SurveyMissionItem.h
+++ b/src/MissionManager/SurveyMissionItem.h
@@ -296,7 +296,7 @@ private:
     static const char* _jsonFixedValueIsAltitudeKey;
     static const char* _jsonRefly90DegreesKey;
 
-    static const int _hoverAndCaptureDelaySeconds = 1;
+    static const int _hoverAndCaptureDelaySeconds = 2;
 };
 
 #endif
diff --git a/src/QGC.cc b/src/QGC.cc
index 812099ab6a0e0ffd2a76bfa96f2c758d9b787159..dcfa7e2d52a6064334d6bd2938a047b46889de4e 100644
--- a/src/QGC.cc
+++ b/src/QGC.cc
@@ -61,14 +61,14 @@ double limitAngleToPMPId(double angle)
         {
             while (angle < -M_PI)
             {
-                angle += M_PI;
+                angle += 2.0f * M_PI;
             }
         }
         else if (angle > M_PI)
         {
             while (angle > M_PI)
             {
-                angle -= M_PI;
+                angle -= 2.0f * M_PI;
             }
         }
     }
diff --git a/src/Terrain.cc b/src/Terrain.cc
index 43367fe32cabbe123d3eebc1a2e4fb78d66265ae..cd2480cf9c53a4a0512514f05f9909b191fc37f7 100644
--- a/src/Terrain.cc
+++ b/src/Terrain.cc
@@ -33,6 +33,8 @@ TerrainBatchManager::TerrainBatchManager(void)
 void TerrainBatchManager::addQuery(ElevationProvider* elevationProvider, const QList<QGeoCoordinate>& coordinates)
 {
     if (coordinates.length() > 0) {
+        qCDebug(ElevationProviderLog) << "addQuery: elevationProvider:coordinates.count" << elevationProvider << coordinates.count();
+        connect(elevationProvider, &ElevationProvider::destroyed, this, &TerrainBatchManager::_elevationProviderDestroyed);
         QueuedRequestInfo_t queuedRequestInfo = { elevationProvider, coordinates };
         _requestQueue.append(queuedRequestInfo);
         if (!_batchTimer.isActive()) {
@@ -43,7 +45,7 @@ void TerrainBatchManager::addQuery(ElevationProvider* elevationProvider, const Q
 
 void TerrainBatchManager::_sendNextBatch(void)
 {
-    qCDebug(ElevationProviderLog) << "_sendNextBatch _state:_requestQueue.count" << (int)_state << _requestQueue.count();
+    qCDebug(ElevationProviderLog) << "_sendNextBatch _state:_requestQueue.count:_sentRequests.count" << _stateToString(_state) << _requestQueue.count() << _sentRequests.count();
 
     if (_state != State::Idle) {
         // Waiting for last download the complete, wait some more
@@ -60,7 +62,7 @@ void TerrainBatchManager::_sendNextBatch(void)
     // Convert coordinates to point strings for json query
     QString points;
     foreach (const QueuedRequestInfo_t& requestInfo, _requestQueue) {
-        SentRequestInfo_t sentRequestInfo = { requestInfo.elevationProvider, requestInfo.coordinates.count() };
+        SentRequestInfo_t sentRequestInfo = { requestInfo.elevationProvider, false, requestInfo.coordinates.count() };
         qCDebug(ElevationProviderLog) << "Building request: coordinate count" << requestInfo.coordinates.count();
         _sentRequests.append(sentRequestInfo);
 
@@ -100,20 +102,23 @@ void TerrainBatchManager::_batchFailed(void)
     QList<float>    noAltitudes;
 
     foreach (const SentRequestInfo_t& sentRequestInfo, _sentRequests) {
-        sentRequestInfo.elevationProvider->_signalTerrainData(false, noAltitudes);
+        if (!sentRequestInfo.providerDestroyed) {
+            disconnect(sentRequestInfo.elevationProvider, &ElevationProvider::destroyed, this, &TerrainBatchManager::_elevationProviderDestroyed);
+            sentRequestInfo.elevationProvider->_signalTerrainData(false, noAltitudes);
+        }
     }
     _sentRequests.clear();
 }
 
 void TerrainBatchManager::_requestFinished()
 {
-    qCDebug(ElevationProviderLog) << "_requestFinished";
     QNetworkReply* reply = qobject_cast<QNetworkReply*>(QObject::sender());
 
     _state = State::Idle;
 
     // When an error occurs we still end up here
     if (reply->error() != QNetworkReply::NoError) {
+        qCDebug(ElevationProviderLog) << "_requestFinished error:" << reply->error();
         _batchFailed();
         reply->deleteLater();
         return;
@@ -124,6 +129,7 @@ void TerrainBatchManager::_requestFinished()
     QJsonParseError parseError;
     QJsonDocument responseJson = QJsonDocument::fromJson(responseBytes, &parseError);
     if (parseError.error != QJsonParseError::NoError) {
+        qCDebug(ElevationProviderLog) << "_requestFinished unable to parse json:" << parseError.errorString();
         _batchFailed();
         reply->deleteLater();
         return;
@@ -132,6 +138,7 @@ void TerrainBatchManager::_requestFinished()
     QJsonObject rootObject = responseJson.object();
     QString status = rootObject["status"].toString();
     if (status != "success") {
+        qCDebug(ElevationProviderLog) << "_requestFinished status != success:" << status;
         _batchFailed();
         reply->deleteLater();
         return;
@@ -145,15 +152,56 @@ void TerrainBatchManager::_requestFinished()
 
     int currentIndex = 0;
     foreach (const SentRequestInfo_t& sentRequestInfo, _sentRequests) {
-        QList<float> requestAltitudes = altitudes.mid(currentIndex, sentRequestInfo.cCoord);
-        sentRequestInfo.elevationProvider->_signalTerrainData(true, requestAltitudes);
-        currentIndex += sentRequestInfo.cCoord;
+        if (!sentRequestInfo.providerDestroyed) {
+            disconnect(sentRequestInfo.elevationProvider, &ElevationProvider::destroyed, this, &TerrainBatchManager::_elevationProviderDestroyed);
+            QList<float> requestAltitudes = altitudes.mid(currentIndex, sentRequestInfo.cCoord);
+            sentRequestInfo.elevationProvider->_signalTerrainData(true, requestAltitudes);
+            currentIndex += sentRequestInfo.cCoord;
+        }
     }
     _sentRequests.clear();
 
     reply->deleteLater();
 }
 
+void TerrainBatchManager::_elevationProviderDestroyed(QObject* elevationProvider)
+{
+    // Remove/Mark deleted objects queries from queues
+
+    qCDebug(ElevationProviderLog) << "_elevationProviderDestroyed elevationProvider" << elevationProvider;
+
+    int i = 0;
+    while (i < _requestQueue.count()) {
+        const QueuedRequestInfo_t& requestInfo = _requestQueue[i];
+        if (requestInfo.elevationProvider == elevationProvider) {
+            qCDebug(ElevationProviderLog) << "Removing deleted provider from _requestQueue index:elevationProvider" << i << requestInfo.elevationProvider;
+            _requestQueue.removeAt(i);
+        } else {
+            i++;
+        }
+    }
+
+    for (int i=0; i<_sentRequests.count(); i++) {
+        SentRequestInfo_t& sentRequestInfo = _sentRequests[i];
+        if (sentRequestInfo.elevationProvider == elevationProvider) {
+            qCDebug(ElevationProviderLog) << "Zombieing deleted provider from _sentRequests index:elevatationProvider" << sentRequestInfo.elevationProvider;
+            sentRequestInfo.providerDestroyed = true;
+        }
+    }
+}
+
+QString TerrainBatchManager::_stateToString(State state)
+{
+    switch (state) {
+    case State::Idle:
+        return QStringLiteral("Idle");
+    case State::Downloading:
+        return QStringLiteral("Downloading");
+    }
+
+    return QStringLiteral("State unknown");
+}
+
 ElevationProvider::ElevationProvider(QObject* parent)
     : QObject(parent)
 {
@@ -161,7 +209,6 @@ ElevationProvider::ElevationProvider(QObject* parent)
 }
 void ElevationProvider::queryTerrainData(const QList<QGeoCoordinate>& coordinates)
 {
-    qCDebug(ElevationProviderLog) << "queryTerrainData: coordinate count" << coordinates.count();
     if (coordinates.length() == 0) {
         return;
     }
diff --git a/src/Terrain.h b/src/Terrain.h
index 549db64c7b7f22ee3aabcc681e05d559a4d25e3a..92f3f330a98574e3debf9661a1492d0958220e28 100644
--- a/src/Terrain.h
+++ b/src/Terrain.h
@@ -30,8 +30,9 @@ public:
     void addQuery(ElevationProvider* elevationProvider, const QList<QGeoCoordinate>& coordinates);
 
 private slots:
-    void _sendNextBatch     (void);
-    void _requestFinished   (void);
+    void _sendNextBatch                 (void);
+    void _requestFinished               (void);
+    void _elevationProviderDestroyed    (QObject* elevationProvider);
 
 private:
     typedef struct {
@@ -41,6 +42,7 @@ private:
 
     typedef struct {
         ElevationProvider*      elevationProvider;
+        bool                    providerDestroyed;
         int                     cCoord;
     } SentRequestInfo_t;
 
@@ -51,6 +53,7 @@ private:
     };
 
     void _batchFailed(void);
+    QString _stateToString(State state);
 
     QList<QueuedRequestInfo_t>  _requestQueue;
     QList<SentRequestInfo_t>    _sentRequests;