diff --git a/samples/blackmisc/sampleschangeobject.cpp b/samples/blackmisc/sampleschangeobject.cpp
index 9d923a88a..3ad44632a 100644
--- a/samples/blackmisc/sampleschangeobject.cpp
+++ b/samples/blackmisc/sampleschangeobject.cpp
@@ -41,7 +41,7 @@ namespace BlackSample
         QDateTime dtUntil = dtFrom.addSecs(60 * 60); // 1 hour
         QDateTime dtFrom2 = dtUntil;
         QDateTime dtUntil2 = dtUntil.addSecs(60 * 60);
-        CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", CLength(1487, CLengthUnit::ft()));
+        CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", { 1487, CLengthUnit::ft() });
         CAtcStation station1(CCallsign("eddm_twr"), CUser("123456", "Joe Doe"),
                              CFrequency(118.7, CFrequencyUnit::MHz()),
                              geoPos, CLength(50, CLengthUnit::km()), false, dtFrom, dtUntil);
diff --git a/samples/blackmisc/samplescontainer.cpp b/samples/blackmisc/samplescontainer.cpp
index 4b163a8fa..9e91ad787 100644
--- a/samples/blackmisc/samplescontainer.cpp
+++ b/samples/blackmisc/samplescontainer.cpp
@@ -48,7 +48,7 @@ namespace BlackSample
         CFrequency freqEddmTwr(118.7, CFrequencyUnit::MHz());
         CCallsign callsignEddmTwr("eddm_twr");
         CCoordinateGeodetic geoPos =
-            CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", CLength(1487, CLengthUnit::ft()));
+            CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", { 1487, CLengthUnit::ft() });
         CAtcStation station1(callsignEddmTwr, CUser("123456", "Joe Doe"),
                              freqEddmTwr,
                              geoPos, CLength(50, CLengthUnit::km()), false, dtFrom, dtUntil);
diff --git a/samples/blackmisc/samplesjson.cpp b/samples/blackmisc/samplesjson.cpp
index 7100d30ff..16023f1ca 100644
--- a/samples/blackmisc/samplesjson.cpp
+++ b/samples/blackmisc/samplesjson.cpp
@@ -63,7 +63,7 @@ namespace BlackSample
         qDebug() << "-------";
         QDateTime dtFrom = QDateTime::currentDateTimeUtc();
         QDateTime dtUntil = dtFrom.addSecs(60 * 60); // 1 hour
-        CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", CLength(1487, CLengthUnit::ft()));
+        CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", { 1487, CLengthUnit::ft() });
         CAtcStation station(CCallsign("eddm_twr"), CUser("123456", "Joe Doe"),
                             CFrequency(118.7, CFrequencyUnit::MHz()), geoPos, CLength(50, CLengthUnit::km()), false, dtFrom, dtUntil);
         json = station.toJson();
diff --git a/samples/blackmiscdbus/servicetool.cpp b/samples/blackmiscdbus/servicetool.cpp
index d2321b381..ffb98705e 100644
--- a/samples/blackmiscdbus/servicetool.cpp
+++ b/samples/blackmiscdbus/servicetool.cpp
@@ -360,7 +360,7 @@ namespace BlackSample
             testserviceInterface.receiveCallsign(callsign);
             qDebug() << "Send callsign via interface" << callsign;
 
-            CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", CLength(1487, CLengthUnit::ft())); // Munich
+            CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", { 1487, CLengthUnit::ft() }); // Munich
             CAtcStation station(CCallsign("eddm_twr"), CUser("123456", "Joe Controller"),
                                 CFrequency(118.7, CFrequencyUnit::MHz()),
                                 geoPos, CLength(50, CLengthUnit::km()));
@@ -370,7 +370,7 @@ namespace BlackSample
 
             // Geo
             // EDDF: 50° 2′ 0″ N, 8° 34′ 14″ E, 100m MSL
-            geoPos = CCoordinateGeodetic::fromWgs84("50° 2′ 1″ 23 N", "8° 34′ 14″ E", CLength(111, CLengthUnit::m()));
+            geoPos = CCoordinateGeodetic::fromWgs84("50° 2′ 1″ 23 N", "8° 34′ 14″ E", { 111, CLengthUnit::m() });
             testserviceInterface.receiveGeoPosition(geoPos);
             qDebug() << "Send geo position" << geoPos;
 
diff --git a/samples/blackmiscdbus/testservice.cpp b/samples/blackmiscdbus/testservice.cpp
index bc061750f..6c36c3ec0 100644
--- a/samples/blackmiscdbus/testservice.cpp
+++ b/samples/blackmiscdbus/testservice.cpp
@@ -94,7 +94,7 @@ namespace BlackSample
      */
     CAtcStation Testservice::getAtcStation() const
     {
-        CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", CLength(1487, CLengthUnit::ft())); // Munich
+        CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", { 1487, CLengthUnit::ft() }); // Munich
         CAtcStation station(CCallsign("eddm_twr"), CUser("654321", "client"),
                             CFrequency(118.7, CFrequencyUnit::MHz()),
                             geoPos, CLength(50, CLengthUnit::km()));
diff --git a/samples/blackmiscquantities/samplesaviation.cpp b/samples/blackmiscquantities/samplesaviation.cpp
index 6ce169e2b..f586fded6 100644
--- a/samples/blackmiscquantities/samplesaviation.cpp
+++ b/samples/blackmiscquantities/samplesaviation.cpp
@@ -74,7 +74,7 @@ namespace BlackSample
         QDateTime dtFrom2 = dtUntil;
         QDateTime dtUntil2 = dtUntil.addSecs(60 * 60);
         CCoordinateGeodetic geoPos =
-            CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", CLength(1487, CLengthUnit::ft()));
+            CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", { 1487, CLengthUnit::ft() });
         CAtcStation station1(CCallsign("eddm_twr"), CUser("123456", "Joe Doe"),
                              CFrequency(118.7, CFrequencyUnit::MHz()),
                              geoPos, CLength(50, CLengthUnit::km()), false, dtFrom, dtUntil);
diff --git a/src/blackgui/models/airportlistmodel.cpp b/src/blackgui/models/airportlistmodel.cpp
index 5efe73311..5a9a517cc 100644
--- a/src/blackgui/models/airportlistmodel.cpp
+++ b/src/blackgui/models/airportlistmodel.cpp
@@ -32,7 +32,7 @@ namespace BlackGui
             this->m_columns.addColumn(CColumn("distance", CAirport::IndexRelativeDistance, new CAirspaceDistanceFormatter()));
             this->m_columns.addColumn(CColumn("bearing", CAirport::IndexRelativeBearing, new CAngleDegreeFormatter()));
             this->m_columns.addColumn(CColumn::standardString("name", CAirport::IndexDescriptiveName));
-            this->m_columns.addColumn(CColumn("elevation", CAirport::IndexElevation, new CPhysiqalQuantiyFormatter<CLengthUnit, CLength>(CLengthUnit::ft(), 0)));
+            this->m_columns.addColumn(CColumn("elevation", CAirport::IndexElevation, new CAltitudeFormatter()));
             this->m_columns.addColumn(CColumn("latitude", CAirport::IndexLatitude, new CLatLonFormatter()));
             this->m_columns.addColumn(CColumn("longitude", CAirport::IndexLatitude, new CLatLonFormatter()));
 
diff --git a/src/blackmisc/aviation/aircraftsituation.h b/src/blackmisc/aviation/aircraftsituation.h
index 6e303495c..580819a2d 100644
--- a/src/blackmisc/aviation/aircraftsituation.h
+++ b/src/blackmisc/aviation/aircraftsituation.h
@@ -66,7 +66,7 @@ namespace BlackMisc
                                const BlackMisc::PhysicalQuantities::CAngle &pitch = {},
                                const BlackMisc::PhysicalQuantities::CAngle &bank = {},
                                const BlackMisc::PhysicalQuantities::CSpeed &gs = {},
-                               const BlackMisc::Aviation::CAltitude &groundElevation = { { 0, nullptr }, BlackMisc::Aviation::CAltitude::MeanSeaLevel });
+                               const BlackMisc::Aviation::CAltitude &groundElevation = { 0, nullptr });
 
             //! Comprehensive constructor
             CAircraftSituation(const BlackMisc::Aviation::CCallsign &correspondingCallsign,
@@ -75,7 +75,7 @@ namespace BlackMisc
                                const BlackMisc::PhysicalQuantities::CAngle &pitch = {},
                                const BlackMisc::PhysicalQuantities::CAngle &bank = {},
                                const BlackMisc::PhysicalQuantities::CSpeed &gs = {},
-                               const BlackMisc::Aviation::CAltitude &groundElevation = { { 0, nullptr }, BlackMisc::Aviation::CAltitude::MeanSeaLevel });
+                               const BlackMisc::Aviation::CAltitude &groundElevation = { 0, nullptr });
 
             //! \copydoc BlackMisc::Mixin::Index::propertyByIndex
             CVariant propertyByIndex(const BlackMisc::CPropertyIndex &index) const;
diff --git a/src/blackmisc/aviation/airport.cpp b/src/blackmisc/aviation/airport.cpp
index 611d9a4ab..9e44b887b 100644
--- a/src/blackmisc/aviation/airport.cpp
+++ b/src/blackmisc/aviation/airport.cpp
@@ -61,7 +61,7 @@ namespace BlackMisc
         {
             CAirport airport(json.value(prefix + "icao").toString());
             airport.setDescriptiveName(json.value(prefix + "name").toString());
-            airport.setElevation(CLength(json.value(prefix + "altitude").toInt(), CLengthUnit::ft()));
+            airport.setElevation(CAltitude(json.value(prefix + "altitude").toInt(), CLengthUnit::ft()));
             const CCoordinateGeodetic pos(json.value(prefix + "latitude").toDouble(), json.value(prefix + "longitude").toDouble(), 0);
             airport.setPosition(pos);
             airport.setOperating(json.value(prefix + "operating").toString() == QStringLiteral("Y"));
diff --git a/src/blackmisc/aviation/airport.h b/src/blackmisc/aviation/airport.h
index 819eb1f89..8a073665f 100644
--- a/src/blackmisc/aviation/airport.h
+++ b/src/blackmisc/aviation/airport.h
@@ -93,11 +93,11 @@ namespace BlackMisc
 
             //! Elevation
             //! \sa geodeticHeight
-            const BlackMisc::PhysicalQuantities::CLength getElevation() const { return this->geodeticHeight(); }
+            const BlackMisc::Aviation::CAltitude &getElevation() const { return this->geodeticHeight(); }
 
             //! Elevation
             //! \sa setGeodeticHeight
-            void setElevation(const BlackMisc::PhysicalQuantities::CLength &elevation) { return this->m_position.setGeodeticHeight(elevation); }
+            void setElevation(const BlackMisc::Aviation::CAltitude &elevation) { return this->m_position.setGeodeticHeight(elevation); }
 
             //! Is the airport still active?
             bool isOperating() const { return m_operating; }
@@ -109,8 +109,7 @@ namespace BlackMisc
             void updateMissingParts(const CAirport &airport);
 
             //! \copydoc Geo::ICoordinateGeodetic::geodeticHeight
-            //! \remarks this should be used for elevation as depicted here: http://en.wikipedia.org/wiki/Altitude#mediaviewer/File:Vertical_distances.svg
-            const BlackMisc::PhysicalQuantities::CLength &geodeticHeight() const override { return this->m_position.geodeticHeight(); }
+            const BlackMisc::Aviation::CAltitude &geodeticHeight() const override { return this->m_position.geodeticHeight(); }
 
             //! Valid ICAO code
             bool hasValidIcaoCode() const { return !this->getIcao().isEmpty(); }
diff --git a/src/blackmisc/aviation/altitude.h b/src/blackmisc/aviation/altitude.h
index 2641a0f1f..9c1228455 100644
--- a/src/blackmisc/aviation/altitude.h
+++ b/src/blackmisc/aviation/altitude.h
@@ -79,6 +79,9 @@ namespace BlackMisc
             //! Constructor
             CAltitude(double value, ReferenceDatum datum, const BlackMisc::PhysicalQuantities::CLengthUnit &unit) : CLength(value, unit), m_datum(datum) {}
 
+            //! Constructor
+            CAltitude(double value, const BlackMisc::PhysicalQuantities::CLengthUnit &unit) : CLength(value, unit), m_datum(MeanSeaLevel) {}
+
             //! Altitude as string
             CAltitude(const QString &altitudeAsString, BlackMisc::PhysicalQuantities::CPqString::SeparatorMode mode = BlackMisc::PhysicalQuantities::CPqString::SeparatorsLocale);
 
diff --git a/src/blackmisc/aviation/atcstation.cpp b/src/blackmisc/aviation/atcstation.cpp
index af026d6b0..666e8467e 100644
--- a/src/blackmisc/aviation/atcstation.cpp
+++ b/src/blackmisc/aviation/atcstation.cpp
@@ -340,7 +340,7 @@ namespace BlackMisc
             return this->getPosition().longitude();
         }
 
-        const CLength &CAtcStation::geodeticHeight() const
+        const CAltitude &CAtcStation::geodeticHeight() const
         {
             return this->m_position.geodeticHeight();
         }
diff --git a/src/blackmisc/aviation/atcstation.h b/src/blackmisc/aviation/atcstation.h
index 8d5788004..dddf2df4a 100644
--- a/src/blackmisc/aviation/atcstation.h
+++ b/src/blackmisc/aviation/atcstation.h
@@ -236,8 +236,7 @@ namespace BlackMisc
             virtual BlackMisc::Geo::CLongitude longitude() const override;
 
             //! \copydoc Geo::ICoordinateGeodetic::geodeticHeight
-            //! \remarks this should be used for elevation as depicted here: http://en.wikipedia.org/wiki/Altitude#mediaviewer/File:Vertical_distances.svg
-            const BlackMisc::PhysicalQuantities::CLength &geodeticHeight() const override;
+            const BlackMisc::Aviation::CAltitude &geodeticHeight() const override;
 
             //! \copydoc Geo::ICoordinateGeodetic::normalVector
             virtual QVector3D normalVector() const override;
diff --git a/src/blackmisc/geo/coordinategeodetic.cpp b/src/blackmisc/geo/coordinategeodetic.cpp
index 4731139c3..b9e3cb390 100644
--- a/src/blackmisc/geo/coordinategeodetic.cpp
+++ b/src/blackmisc/geo/coordinategeodetic.cpp
@@ -16,6 +16,7 @@
 #include <QtGlobal>
 #include <cmath>
 
+using namespace BlackMisc::Aviation;
 using namespace BlackMisc::PhysicalQuantities;
 using namespace BlackMisc::Math;
 
@@ -29,7 +30,7 @@ namespace BlackMisc
             return s.arg(this->latitude().valueRoundedWithUnit(6, i18n)).arg(this->longitude().valueRoundedWithUnit(6, i18n)).arg(this->m_geodeticHeight.valueRoundedWithUnit(6, i18n));
         }
 
-        CCoordinateGeodetic CCoordinateGeodetic::fromWgs84(const QString &latitudeWgs84, const QString &longitudeWgs84, const CLength &geodeticHeight)
+        CCoordinateGeodetic CCoordinateGeodetic::fromWgs84(const QString &latitudeWgs84, const QString &longitudeWgs84, const CAltitude &geodeticHeight)
         {
             CLatitude lat = CLatitude::fromWgs84(latitudeWgs84);
             CLongitude lon = CLongitude::fromWgs84(longitudeWgs84);
@@ -189,7 +190,7 @@ namespace BlackMisc
             }
         }
 
-        CCoordinateGeodetic::CCoordinateGeodetic(CLatitude latitude, CLongitude longitude, BlackMisc::PhysicalQuantities::CLength geodeticHeight) :
+        CCoordinateGeodetic::CCoordinateGeodetic(CLatitude latitude, CLongitude longitude, CAltitude geodeticHeight) :
             m_x(latitude.cos() * longitude.cos()),
             m_y(latitude.cos() * longitude.sin()),
             m_z(latitude.sin()),
diff --git a/src/blackmisc/geo/coordinategeodetic.h b/src/blackmisc/geo/coordinategeodetic.h
index a8fc0e796..dacbcd5a9 100644
--- a/src/blackmisc/geo/coordinategeodetic.h
+++ b/src/blackmisc/geo/coordinategeodetic.h
@@ -13,6 +13,7 @@
 #define BLACKMISC_COORDINATEGEODETIC_H
 
 #include "blackmisc/blackmiscexport.h"
+#include "blackmisc/aviation/altitude.h"
 #include "blackmisc/geo/latitude.h"
 #include "blackmisc/geo/longitude.h"
 #include "blackmisc/metaclass.h"
@@ -32,7 +33,9 @@ namespace BlackMisc
 {
     namespace Geo
     {
-        //! Geodetic coordinate
+        //! Geodetic coordinate, a position in 3D space relative to the reference geoid.
+        //!
+        //! Composed of a latitude, longitude, and height (aka altitude, aka elevation).
         //! \sa http://www.esri.com/news/arcuser/0703/geoid1of3.html
         //! \sa http://http://www.gmat.unsw.edu.au/snap/gps/clynch_pdfs/coordcvt.pdf (page 5)
         //! \sa http://en.wikipedia.org/wiki/Geodetic_datum#Vertical_datum
@@ -61,10 +64,15 @@ namespace BlackMisc
             virtual CLongitude longitude() const = 0;
 
             //! Height, ellipsoidal or geodetic height (used in GPS)
-            //! This is approximately MSL (orthometric) height, aka elevation.
+            //!
+            //! This is approximately MSL (orthometric) height, aka altitude, aka elevation.
+            //! The terms "geodetic height", "altitude", and "elevation" are interchangable.
+            //! "Geodetic height" is the generic, context-free term for the vertical component of a position.
+            //! This is commonly called "altitude" for objects that can move freely in the vertical component.
+            //! By a similar convention, "elevation" is commonly used for objects that are fixed to the ground.
             //! \sa see http://www.gmat.unsw.edu.au/snap/gps/clynch_pdfs/coordcvt.pdf page 5
             //! \sa http://www.esri.com/news/arcuser/0703/geoid1of3.html
-            virtual const BlackMisc::PhysicalQuantities::CLength &geodeticHeight() const = 0;
+            virtual const BlackMisc::Aviation::CAltitude &geodeticHeight() const = 0;
 
             //! Normal vector
             //! \note QVector3D uses floats, so don't use if double precision is needed
@@ -180,7 +188,7 @@ namespace BlackMisc
             CCoordinateGeodetic(const QVector3D &normal) : m_x(normal.x()), m_y(normal.y()), m_z(normal.z()) {}
 
             //! Constructor by values
-            CCoordinateGeodetic(CLatitude latitude, CLongitude longitude, BlackMisc::PhysicalQuantities::CLength geodeticHeight);
+            CCoordinateGeodetic(CLatitude latitude, CLongitude longitude, BlackMisc::Aviation::CAltitude geodeticHeight);
 
             //! Constructor by double values, but no geodetic height
             CCoordinateGeodetic(double latitudeDegrees, double longitudeDegrees);
@@ -195,7 +203,7 @@ namespace BlackMisc
             virtual CLongitude longitude() const override;
 
             //! \copydoc ICoordinateGeodetic::geodeticHeight
-            virtual const BlackMisc::PhysicalQuantities::CLength &geodeticHeight() const override { return this->m_geodeticHeight; }
+            virtual const BlackMisc::Aviation::CAltitude &geodeticHeight() const override { return this->m_geodeticHeight; }
 
             //! \copydoc ICoordinateGeodetic::normalVector
             virtual QVector3D normalVector() const override;
@@ -222,7 +230,7 @@ namespace BlackMisc
             void setLatLong(const CLatitude &latitude, const CLongitude &longitude);
 
             //! Set height (ellipsoidal or geodetic height)
-            void setGeodeticHeight(const BlackMisc::PhysicalQuantities::CLength &height) { this->m_geodeticHeight = height; }
+            void setGeodeticHeight(const BlackMisc::Aviation::CAltitude &height) { this->m_geodeticHeight = height; }
 
             //! Set normal vector
             void setNormalVector(const QVector3D &normal) { this->m_x = normal.x(); this->m_y = normal.y(); this->m_z = normal.z(); }
@@ -231,7 +239,7 @@ namespace BlackMisc
             void setNormalVector(double x, double y, double z) { this->m_x = x; this->m_y = y; this->m_z = z; }
 
             //! Coordinate by WGS84 position data
-            static CCoordinateGeodetic fromWgs84(const QString &latitudeWgs84, const QString &longitudeWgs84, const BlackMisc::PhysicalQuantities::CLength &geodeticHeight = {});
+            static CCoordinateGeodetic fromWgs84(const QString &latitudeWgs84, const QString &longitudeWgs84, const BlackMisc::Aviation::CAltitude &geodeticHeight = {});
 
             //! \copydoc BlackMisc::Mixin::String::toQString
             QString convertToQString(bool i18n = false) const;
@@ -240,7 +248,7 @@ namespace BlackMisc
             double m_x = 0; //!< normal vector
             double m_y = 0; //!< normal vector
             double m_z = 0; //!< normal vector
-            BlackMisc::PhysicalQuantities::CLength m_geodeticHeight { 0, nullptr }; //!< height, ellipsoidal or geodetic height
+            BlackMisc::Aviation::CAltitude m_geodeticHeight { 0, nullptr }; //!< height, ellipsoidal or geodetic height
 
             BLACK_METACLASS(
                 CCoordinateGeodetic,
diff --git a/src/blackmisc/simulation/simulatedaircraft.h b/src/blackmisc/simulation/simulatedaircraft.h
index 1f154ef67..8ac8c0465 100644
--- a/src/blackmisc/simulation/simulatedaircraft.h
+++ b/src/blackmisc/simulation/simulatedaircraft.h
@@ -195,7 +195,7 @@ namespace BlackMisc
             virtual BlackMisc::Geo::CLongitude longitude() const override { return this->m_situation.longitude(); }
 
             //! \copydoc BlackMisc::Geo::ICoordinateGeodetic::geodeticHeight
-            const BlackMisc::PhysicalQuantities::CLength &geodeticHeight() const override { return this->m_situation.geodeticHeight(); }
+            const BlackMisc::Aviation::CAltitude &geodeticHeight() const override { return this->m_situation.geodeticHeight(); }
 
             //! \copydoc BlackMisc::Geo::ICoordinateGeodetic::normalVector
             virtual QVector3D normalVector() const override { return this->m_situation.normalVector(); }
diff --git a/src/blackmisc/simulation/xplane/navdatareference.h b/src/blackmisc/simulation/xplane/navdatareference.h
index 15059b3a2..db4594bcf 100644
--- a/src/blackmisc/simulation/xplane/navdatareference.h
+++ b/src/blackmisc/simulation/xplane/navdatareference.h
@@ -57,7 +57,7 @@ namespace BlackMisc
 
                 virtual Geo::CLatitude latitude() const override { return m_position.latitude(); }
                 virtual Geo::CLongitude longitude() const override { return m_position.longitude(); }
-                virtual const PhysicalQuantities::CLength &geodeticHeight() const override { return m_position.geodeticHeight(); }
+                virtual const Aviation::CAltitude &geodeticHeight() const override { return m_position.geodeticHeight(); }
                 virtual QVector3D normalVector() const override { return m_position.normalVector(); }
                 virtual std::array<double, 3> normalVectorDouble() const override { return this->m_position.normalVectorDouble(); }
 
diff --git a/src/blackmisc/testing.cpp b/src/blackmisc/testing.cpp
index 0f534f4a3..6e06be914 100644
--- a/src/blackmisc/testing.cpp
+++ b/src/blackmisc/testing.cpp
@@ -27,6 +27,7 @@
 #include <tuple>
 
 using namespace BlackMisc;
+using namespace BlackMisc::Aviation;
 using namespace BlackMisc::Geo;
 using namespace BlackMisc::Network;
 using namespace BlackMisc::PhysicalQuantities;
@@ -49,7 +50,7 @@ namespace BlackMisc
         {
             // from WGS is slow, so static const (only 1 time init)
             // https://dev.vatsim-germany.org/issues/322#note-2
-            static const CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", CLength(index, CLengthUnit::ft()));
+            static const CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", CAltitude(index, CLengthUnit::ft()));
             QString cs = QString("%1_TWR").arg(index);
             QString usr = QString("Joe %1").arg(index);
             QString id = QString("00000%1").arg(index).right(6);
@@ -164,11 +165,11 @@ namespace BlackMisc
             );
 
             CCoordinateGeodetic c;
-            const CLength h(333, CLengthUnit::m());
+            const CAltitude a(333, CLengthUnit::m());
             for (int i = 0; i < times; i++)
             {
                 int idx = (i % 5) * 2;
-                c = CCoordinateGeodetic::fromWgs84(wgsLatLng.at(idx), wgsLatLng.at(idx + 1), h);
+                c = CCoordinateGeodetic::fromWgs84(wgsLatLng.at(idx), wgsLatLng.at(idx + 1), a);
             }
         }
     } // namespace
diff --git a/src/plugins/simulator/fscommon/fsuipc.cpp b/src/plugins/simulator/fscommon/fsuipc.cpp
index 12ab43fce..4f1f84d8a 100644
--- a/src/plugins/simulator/fscommon/fsuipc.cpp
+++ b/src/plugins/simulator/fscommon/fsuipc.cpp
@@ -350,7 +350,7 @@ namespace BlackSimPlugin
                     CCoordinateGeodetic position = situation.getPosition();
                     CLatitude lat(latitudeRaw * latCorrectionFactor, CAngleUnit::deg());
                     CLongitude lon(longitudeRaw * lonCorrectionFactor, CAngleUnit::deg());
-                    CLength groundAltitude(groundAltitudeRaw / 256.0, CLengthUnit::m());
+                    CAltitude groundAltitude(groundAltitudeRaw / 256.0, CLengthUnit::m());
                     position.setLatitude(lat);
                     position.setLongitude(lon);
                     position.setGeodeticHeight(groundAltitude);
diff --git a/src/plugins/simulator/xplane/simulatorxplane.cpp b/src/plugins/simulator/xplane/simulatorxplane.cpp
index 8445da9d4..2ad7a30e4 100644
--- a/src/plugins/simulator/xplane/simulatorxplane.cpp
+++ b/src/plugins/simulator/xplane/simulatorxplane.cpp
@@ -364,7 +364,7 @@ namespace BlackSimPlugin
                 using namespace BlackMisc::PhysicalQuantities;
                 using namespace BlackMisc::Geo;
 
-                m_airportsInRange.push_back({ *icaoIt, { CLatitude(*latIt, CAngleUnit::deg()), CLongitude(*lonIt, CAngleUnit::deg()), CLength(*altIt, CLengthUnit::ft()) }, *nameIt });
+                m_airportsInRange.push_back({ *icaoIt, { CLatitude(*latIt, CAngleUnit::deg()), CLongitude(*lonIt, CAngleUnit::deg()), CAltitude(*altIt, CLengthUnit::ft()) }, *nameIt });
             }
         }
 
diff --git a/src/swiftguistandard/swiftguistdaircraft.cpp b/src/swiftguistandard/swiftguistdaircraft.cpp
index 9c69e77e7..9c81ff91f 100644
--- a/src/swiftguistandard/swiftguistdaircraft.cpp
+++ b/src/swiftguistandard/swiftguistdaircraft.cpp
@@ -58,7 +58,7 @@ void SwiftGuiStd::setTestPosition(const QString &wgsLatitude, const QString &wgs
     CCoordinateGeodetic coordinate(
         CLatitude::fromWgs84(wgsLatitude),
         CLongitude::fromWgs84(wgsLongitude),
-        CLength(0, CLengthUnit::m()));
+        CAltitude(0, CLengthUnit::m()));
 
     this->m_ownAircraft.setPosition(coordinate);
     this->m_ownAircraft.setAltitude(altitude);
diff --git a/tests/blackcore/testreaders.cpp b/tests/blackcore/testreaders.cpp
index cf10f4d87..69f1e2d7b 100644
--- a/tests/blackcore/testreaders.cpp
+++ b/tests/blackcore/testreaders.cpp
@@ -135,7 +135,7 @@ namespace BlackCoreTest
         QVERIFY2(heathrow[0].isOperating(), "Wrong airport data");
 
         auto airports = m_airportReader->getAirports();
-        airports.sortByRange(CCoordinateGeodetic(CLatitude(51.5085300, CAngleUnit::deg()), CLongitude(-0.1257400, CAngleUnit::deg()), CLength()), true);
+        airports.sortByRange(CCoordinateGeodetic(CLatitude(51.5085300, CAngleUnit::deg()), CLongitude(-0.1257400, CAngleUnit::deg()), CAltitude()), true);
         QVERIFY2(airports[0].getIcao() == CAirportIcaoCode("EGLW"), "Wrong airport data");
 
         CApplication::processEventsFor(2500); // make sure events are processed
diff --git a/tests/blackmisc/testvariantandmap.cpp b/tests/blackmisc/testvariantandmap.cpp
index c7fb89f43..d4971cd2d 100644
--- a/tests/blackmisc/testvariantandmap.cpp
+++ b/tests/blackmisc/testvariantandmap.cpp
@@ -49,7 +49,7 @@ namespace BlackMiscTest
         QDateTime dtFrom2 = dtUntil;
         QDateTime dtUntil2 = dtUntil.addSecs(60 * 60);
         CCoordinateGeodetic geoPos =
-            CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", CLength(1487, CLengthUnit::ft()));
+            CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", { 1487, CLengthUnit::ft() });
         CAtcStation station1(CCallsign("eddm_twr"), CUser("123456", "Joe Doe"),
                              CFrequency(118.7, CFrequencyUnit::MHz()),
                              geoPos, CLength(50, CLengthUnit::km()), false, dtFrom, dtUntil);
@@ -98,7 +98,7 @@ namespace BlackMiscTest
         QDateTime dtFrom = QDateTime::currentDateTimeUtc();
         QDateTime dtUntil = dtFrom.addSecs(60 * 60); // 1 hour
         CCoordinateGeodetic geoPos =
-            CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", CLength(1487, CLengthUnit::ft()));
+            CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", { 1487, CLengthUnit::ft() });
         CAtcStation station1(CCallsign("eddm_twr"), CUser("123456", "Joe Doe"),
                              CFrequency(118.7, CFrequencyUnit::MHz()),
                              geoPos, CLength(50, CLengthUnit::km()), false, dtFrom, dtUntil);