mavlink · HTRamsey · Jul 3, 2025
diff --git a/src/FlightDisplay/VehicleWarnings.qml b/src/FlightDisplay/VehicleWarnings.qml
@@ -12,18 +12,28 @@ import QtQuick
 import QGroundControl
 import QGroundControl.ScreenTools
 import QGroundControl.Controls
+import QGroundControl.FactSystem
 
 Rectangle {
     anchors.margins:    -ScreenTools.defaultFontPixelHeight
     height:             warningsCol.height
     width:              warningsCol.width
     color:              Qt.rgba(1, 1, 1, 0.5)
     radius:             ScreenTools.defaultFontPixelWidth / 2
-    visible:            _noGPSLockVisible || _prearmErrorVisible
+    visible:            _noGPSLockVisible || _prearmErrorVisible || (_showAltitudeWarning && (_vehicleAltitudeBelowMin || _vehicleAltitudeAboveMax || !_terrainDataAvailable.value))
 
     property var  _activeVehicle:       QGroundControl.multiVehicleManager.activeVehicle
     property bool _noGPSLockVisible:    _activeVehicle && _activeVehicle.requiresGpsFix && !_activeVehicle.coordinate.isValid
-    property bool _prearmErrorVisible:  _activeVehicle && !_activeVehicle.armed && _activeVehicle.prearmError && !_activeVehicle.healthAndArmingCheckReport.supported
+    property bool _prearmErrorVisible:  _activeVehicle && !_activeVehicle.armed && _activeVehicle.prearmError
+
+    property Fact _altitudeWarnThresholdEnabled: QGroundControl.settingsManager.flyViewSettings.altitudeWarnThresholdEnabled
+    property Fact _altitudeWarnMinAGL: QGroundControl.settingsManager.flyViewSettings.altitudeWarnMinAGL
+    property Fact _altitudeWarnMaxAGL: QGroundControl.settingsManager.flyViewSettings.altitudeWarnMaxAGL
+    property Fact _altitudeAboveTerrain: _activeVehicle ? _activeVehicle.altitudeAboveTerr : null
+    property Fact _terrainDataAvailable: _activeVehicle ? _activeVehicle.terrainDataAvailable : null
+    property bool _vehicleAltitudeBelowMin: _altitudeAboveTerrain ? (_altitudeAboveTerrain.value < _altitudeWarnMinAGL.value) : false
+    property bool _vehicleAltitudeAboveMax: _altitudeAboveTerrain ? (_altitudeAboveTerrain.value > _altitudeWarnMaxAGL.value) : false
+    property bool _showAltitudeWarning: _activeVehicle && _activeVehicle.flying && !_activeVehicle.landing && _altitudeWarnThresholdEnabled.value
 
     Column {
         id:         warningsCol
@@ -45,6 +55,30 @@ Rectangle {
             text:                       _activeVehicle ? _activeVehicle.prearmError : ""
         }
 
+        QGCLabel {
+            anchors.horizontalCenter:   parent.horizontalCenter
+            visible:                    _showAltitudeWarning && _terrainDataAvailable.value && _vehicleAltitudeBelowMin
+            color:                      "black"
+            font.pointSize:             ScreenTools.largeFontPointSize
+            text:                       visible ? qsTr("Altitude below minimum threshold of %1 %2 above terrain: (%3 %4)").arg(_altitudeWarnMinAGL.value).arg(_altitudeWarnMinAGL.units).arg(_altitudeAboveTerrain.value.toFixed(2)).arg(_altitudeAboveTerrain.units) : ""
+        }
+
+        QGCLabel {
+            anchors.horizontalCenter:   parent.horizontalCenter
+            visible:                    _showAltitudeWarning && _terrainDataAvailable.value && _vehicleAltitudeAboveMax
+            color:                      "black"
+            font.pointSize:             ScreenTools.largeFontPointSize
+            text:                       visible ? qsTr("Altitude above maximum threshold of %1 %2 above terrain: (%3 %4)").arg(_altitudeWarnMaxAGL.value).arg(_altitudeWarnMaxAGL.units).arg(_altitudeAboveTerrain.value.toFixed(2)).arg(_altitudeAboveTerrain.units) : ""
+        }
+
+        QGCLabel {
+            anchors.horizontalCenter:   parent.horizontalCenter
+            visible:                    _showAltitudeWarning && !_terrainDataAvailable.value
+            color:                      "black"
+            font.pointSize:             ScreenTools.largeFontPointSize
+            text:                       qsTr("Terrain data not available at vehicle pos, altitude warning thresholds are disabled")
+        }
+
         QGCLabel {
             anchors.horizontalCenter:   parent.horizontalCenter
             visible:                    _prearmErrorVisible

diff --git a/src/Settings/FlyView.SettingsGroup.json b/src/Settings/FlyView.SettingsGroup.json
@@ -102,6 +102,33 @@
     "min":          3,
     "max":          60,
     "default":      10
+},
+{
+    "name":            "altitudeWarnThresholdEnabled",
+    "shortDesc":       "Altitude warning threshold enabled",
+    "longDesc":        "If this option is enabled, warn user if drone flies above or below altitude threshold.",
+    "type":            "bool",
+    "default":         false
+},
+{
+    "name":            "altitudeWarnMinAGL",
+    "shortDesc":       "Minimum altitude AGL for warning",
+    "longDesc":        "Minimum altitude warning threshold in meters above ground level.",
+    "type":            "double",
+    "default":         2.0,
+    "min":             0.0,
+    "units":           "m",
+    "decimalPlaces":   1
+},
+{
+    "name":            "altitudeWarnMaxAGL",
+    "shortDesc":       "Minimum altitude AGL for warning",
+    "longDesc":        "Minimum altitude warning threshold in meters above ground level.",
+    "type":            "double",
+    "default":         121.92,
+    "min":             0.0,
+    "units":           "m",
+    "decimalPlaces":   1
 }
 ]
 }
diff --git a/src/Settings/FlyViewSettings.cc b/src/Settings/FlyViewSettings.cc
@@ -31,3 +31,6 @@ DECLARE_SETTINGSFACT(FlyViewSettings, updateHomePosition)
 DECLARE_SETTINGSFACT(FlyViewSettings, instrumentQmlFile2)
 DECLARE_SETTINGSFACT(FlyViewSettings, requestControlAllowTakeover)
 DECLARE_SETTINGSFACT(FlyViewSettings, requestControlTimeout)
+DECLARE_SETTINGSFACT(FlyViewSettings, altitudeWarnThresholdEnabled)
+DECLARE_SETTINGSFACT(FlyViewSettings, altitudeWarnMinAGL)
+DECLARE_SETTINGSFACT(FlyViewSettings, altitudeWarnMaxAGL)
diff --git a/src/Settings/FlyViewSettings.h b/src/Settings/FlyViewSettings.h
@@ -34,4 +34,7 @@ class FlyViewSettings : public SettingsGroup
     DEFINE_SETTINGFACT(instrumentQmlFile2)
     DEFINE_SETTINGFACT(requestControlAllowTakeover)
     DEFINE_SETTINGFACT(requestControlTimeout)
+    DEFINE_SETTINGFACT(altitudeWarnThresholdEnabled)
+    DEFINE_SETTINGFACT(altitudeWarnMinAGL)
+    DEFINE_SETTINGFACT(altitudeWarnMaxAGL)
 };
diff --git a/src/UI/AppSettings/FlyViewSettings.qml b/src/UI/AppSettings/FlyViewSettings.qml
@@ -114,6 +114,34 @@ SettingsPage {
         }
     }
 
+    SettingsGroupLayout {
+        Layout.fillWidth:   true
+        heading:            qsTr("Altitude above ground level warning threshold")
+
+        FactCheckBoxSlider {
+            Layout.fillWidth:   true
+            text:               qsTr("Altitude warning enabled")
+            visible:            fact.visible
+            fact:               _flyViewSettings.altitudeWarnThresholdEnabled
+        }
+
+        LabelledFactTextField {
+            Layout.fillWidth:   true
+            label:              qsTr("Minimum Altitude")
+            fact:               _flyViewSettings.altitudeWarnMinAGL
+            visible:            fact.visible
+            enabled:            _flyViewSettings.altitudeWarnThresholdEnabled.value
+        }
+
+        LabelledFactTextField {
+            Layout.fillWidth:   true
+            label:              qsTr("Maximum Altitude")
+            fact:               _flyViewSettings.altitudeWarnMaxAGL
+            visible:            fact.visible
+            enabled:            _flyViewSettings.altitudeWarnThresholdEnabled.value
+        }
+    }
+
     SettingsGroupLayout {
         Layout.fillWidth:   true
         heading:            qsTr("Guided Commands")

diff --git a/src/Vehicle/FactGroups/VehicleFact.json b/src/Vehicle/FactGroups/VehicleFact.json
@@ -87,6 +87,12 @@
     "decimalPlaces":    1,
     "units":            "m"
 },
+{
+    "name":             "terrainDataAvailable",
+    "shortDesc": "Terrain Data Available",
+    "type":             "bool",
+    "defaultValue":     false
+},
 {
     "name":             "flightDistance",
     "shortDesc": "Flight Distance",

diff --git a/src/Vehicle/FactGroups/VehicleFactGroup.cc b/src/Vehicle/FactGroups/VehicleFactGroup.cc
@@ -30,6 +30,7 @@ VehicleFactGroup::VehicleFactGroup(QObject *parent)
     _addFact(&_altitudeRelativeFact);
     _addFact(&_altitudeAMSLFact);
     _addFact(&_altitudeAboveTerrFact);
+    _addFact(&_terrainDataAvailableFact);
     _addFact(&_altitudeTuningFact);
     _addFact(&_altitudeTuningSetpointFact);
     _addFact(&_xTrackErrorFact);

diff --git a/src/Vehicle/FactGroups/VehicleFactGroup.h b/src/Vehicle/FactGroups/VehicleFactGroup.h
@@ -27,6 +27,7 @@ class VehicleFactGroup : public FactGroup
     Q_PROPERTY(Fact *altitudeRelative       READ altitudeRelative       CONSTANT)
     Q_PROPERTY(Fact *altitudeAMSL           READ altitudeAMSL           CONSTANT)
     Q_PROPERTY(Fact *altitudeAboveTerr      READ altitudeAboveTerr      CONSTANT)
+    Q_PROPERTY(Fact *terrainDataAvailable   READ terrainDataAvailable   CONSTANT)
     Q_PROPERTY(Fact *altitudeTuning         READ altitudeTuning         CONSTANT)
     Q_PROPERTY(Fact *altitudeTuningSetpoint READ altitudeTuningSetpoint CONSTANT)
     Q_PROPERTY(Fact *xTrackError            READ xTrackError            CONSTANT)
@@ -61,6 +62,7 @@ class VehicleFactGroup : public FactGroup
     Fact *altitudeRelative() { return &_altitudeRelativeFact; }
     Fact *altitudeAMSL() { return &_altitudeAMSLFact; }
     Fact *altitudeAboveTerr() { return &_altitudeAboveTerrFact; }
+    Fact *terrainDataAvailable() { return &_terrainDataAvailableFact; }
     Fact *altitudeTuning() { return &_altitudeTuningFact; }
     Fact *altitudeTuningSetpoint() { return &_altitudeTuningSetpointFact; }
     Fact *xTrackError() { return &_xTrackErrorFact; }
@@ -105,6 +107,7 @@ class VehicleFactGroup : public FactGroup
     Fact _altitudeRelativeFact = Fact(0, QStringLiteral("altitudeRelative"), FactMetaData::valueTypeDouble);
     Fact _altitudeAMSLFact = Fact(0, QStringLiteral("altitudeAMSL"), FactMetaData::valueTypeDouble);
     Fact _altitudeAboveTerrFact = Fact(0, QStringLiteral("altitudeAboveTerr"), FactMetaData::valueTypeDouble);
+    Fact _terrainDataAvailableFact = Fact(0, QStringLiteral("terrainDataAvailable"), FactMetaData::valueTypeBool);
     Fact _altitudeTuningFact = Fact(0, QStringLiteral("altitudeTuning"), FactMetaData::valueTypeDouble);
     Fact _altitudeTuningSetpointFact = Fact(0, QStringLiteral("altitudeTuningSetpoint"), FactMetaData::valueTypeDouble);
     Fact _xTrackErrorFact = Fact(0, QStringLiteral("xTrackError"), FactMetaData::valueTypeDouble);

diff --git a/src/Vehicle/Vehicle.cc b/src/Vehicle/Vehicle.cc
@@ -3766,11 +3766,19 @@ void Vehicle::_updateAltAboveTerrain()
 void Vehicle::_altitudeAboveTerrainReceived(bool success, QList<double> heights)
 {
     if (!success) {
-        qCDebug(VehicleLog) << "_altitudeAboveTerrainReceived: terrain data not available for vehicle coordinate";
+        qCDebug(VehicleLog) << "terrain data not available for vehicle coordinate";
+        if (_coordinate.isValid() &&
+            SettingsManager::instance()->flyViewSettings()->altitudeWarnThresholdEnabled()->rawValue().toBool() && _flying) {
+            _terrainDataAvailableFact.setRawValue(false);
+        }
+        _altitudeAboveTerrFact.setRawValue(qQNaN()); // Reset the altitude above terrain fact to NaN
     } else {
+        if (!_terrainDataAvailableFact.rawValue().toBool()) {
+            _terrainDataAvailableFact.setRawValue(true);
+        }
         // Query was succesful, save the data.
-        double terrainAltitude = heights[0];
-        double altitudeAboveTerrain = altitudeAMSL()->rawValue().toDouble() - terrainAltitude;
+        const double terrainAltitude = heights[0];
+        const double altitudeAboveTerrain = altitudeAMSL()->rawValue().toDouble() - terrainAltitude;
         _altitudeAboveTerrFact.setRawValue(altitudeAboveTerrain);
     }
     // Clean up