diff --git a/src/blackmisc/aviation/aircraftsituation.cpp b/src/blackmisc/aviation/aircraftsituation.cpp
index 2f20b4387..680c2f86d 100644
--- a/src/blackmisc/aviation/aircraftsituation.cpp
+++ b/src/blackmisc/aviation/aircraftsituation.cpp
@@ -46,14 +46,15 @@ namespace BlackMisc
 
         QString CAircraftSituation::convertToQString(bool i18n) const
         {
-            const QString s = (m_position.toQString(i18n)) %
-                              QLatin1String(" bank: ") % (m_bank.toQString(i18n)) %
-                              QLatin1String(" pitch: ") % (m_pitch.toQString(i18n)) %
-                              QLatin1String(" gs: ") % (m_groundSpeed.toQString(i18n)) %
-                              QLatin1String(" elevation: ") % (m_groundElevation.toQString(i18n)) %
-                              QLatin1String(" heading: ") % (m_heading.toQString(i18n)) %
-                              QLatin1String(" timestamp: ") % (this->hasValidTimestamp() ? this->getFormattedUtcTimestampDhms() : QStringLiteral("-"));
-            return s;
+            return m_position.toQString(i18n) %
+                   QStringLiteral(" bank: ") % (m_bank.toQString(i18n)) %
+                   QStringLiteral(" pitch: ") % (m_pitch.toQString(i18n)) %
+                   QStringLiteral(" heading: ") % (m_heading.toQString(i18n)) %
+                   QStringLiteral(" og: ") % this->getOnGroundInfo() %
+                   QStringLiteral(" gs: ") % m_groundSpeed.valueRoundedWithUnit(CSpeedUnit::kts(), 1, true) %
+                   QStringLiteral(" ") % m_groundSpeed.valueRoundedWithUnit(CSpeedUnit::m_s(), 1, true) %
+                   QStringLiteral(" elevation: ") % (m_groundElevation.toQString(i18n)) %
+                   QStringLiteral(" timestamp: ") % (this->hasValidTimestamp() ? this->getFormattedUtcTimestampDhms() : QStringLiteral("-"));
         }
 
         const QString &CAircraftSituation::isOnGroundToString(CAircraftSituation::IsOnGround onGround)
@@ -104,7 +105,7 @@ namespace BlackMisc
             case IndexLatitude: return this->latitude().propertyByIndex(index.copyFrontRemoved());
             case IndexLongitude: return this->longitude().propertyByIndex(index.copyFrontRemoved());
             case IndexAltitude: return this->getAltitude().propertyByIndex(index.copyFrontRemoved());
-            case IndexHeading: return m_heading.propertyByIndex(index.copyFrontRemoved());
+            case IndexHeading:return m_heading.propertyByIndex(index.copyFrontRemoved());
             case IndexPitch: return m_pitch.propertyByIndex(index.copyFrontRemoved());
             case IndexBank: return m_bank.propertyByIndex(index.copyFrontRemoved());
             case IndexGroundSpeed: return m_groundSpeed.propertyByIndex(index.copyFrontRemoved());
@@ -121,11 +122,7 @@ namespace BlackMisc
         void CAircraftSituation::setPropertyByIndex(const CPropertyIndex &index, const CVariant &variant)
         {
             if (index.isMyself()) { (*this) = variant.to<CAircraftSituation>(); return; }
-            if (ITimestampBased::canHandleIndex(index))
-            {
-                ITimestampBased::setPropertyByIndex(index, variant);
-                return;
-            }
+            if (ITimestampBased::canHandleIndex(index)) { ITimestampBased::setPropertyByIndex(index, variant); return; }
 
             const ColumnIndex i = index.frontCasted<ColumnIndex>();
             switch (i)
@@ -201,6 +198,13 @@ namespace BlackMisc
             return !this->getGroundElevation().isNull();
         }
 
+        void CAircraftSituation::setGroundElevationChecked(const CAltitude &elevation, bool ignoreNullValues, bool overrideExisting)
+        {
+            if (ignoreNullValues && elevation.isNull()) { return; }
+            if (!overrideExisting && this->hasGroundElevation()) { return; }
+            m_groundElevation = elevation;
+        }
+
         CLength CAircraftSituation::getHeightAboveGround() const
         {
             if (this->getAltitude().isNull()) { return { 0, nullptr }; }
@@ -214,14 +218,30 @@ namespace BlackMisc
             return this->getAltitude() - gh;
         }
 
-        CAltitude CAircraftSituation::getCorrectedAltitude(const CLength &centerOfGravity) const
+        CAltitude CAircraftSituation::getCorrectedAltitude(const CLength &centerOfGravity, bool *corrected) const
         {
-            CAltitude altPlusCG = this->getAltitude();
-            if (!centerOfGravity.isNull()) { altPlusCG += centerOfGravity; }
-            if (this->getGroundElevation().isNull()) { return altPlusCG; }
-            if (this->getAltitude().getReferenceDatum() != CAltitude::MeanSeaLevel) { return altPlusCG; }
-            if (this->getGroundElevation() < this->getAltitude()) { return altPlusCG; }
-            return this->getGroundElevation();
+            if (corrected) { *corrected = false; }
+            if (this->getGroundElevation().isNull()) { return this->getAltitude(); }
+
+            // above ground
+            if (this->getAltitude().getReferenceDatum() == CAltitude::AboveGround)
+            {
+                const CAltitude aboveGround = this->getAltitude().withOffset(centerOfGravity);
+                const bool c = !aboveGround.isPositiveWithEpsilonConsidered();
+                if (corrected) { *corrected = c; }
+                return c ?
+                       CAltitude(0, CAltitude::AboveGround, aboveGround.getUnit()) :
+                       aboveGround;
+            }
+            else
+            {
+                CAltitude groundPlusCG = this->getGroundElevation().withOffset(centerOfGravity);
+                const bool c = (this->getAltitude() < groundPlusCG);
+                if (corrected) { *corrected = c; }
+                return c ?
+                       groundPlusCG :
+                       this->getAltitude();
+            }
         }
 
         void CAircraftSituation::setPressureAltitude(const CAltitude &altitude)
@@ -230,6 +250,22 @@ namespace BlackMisc
             m_pressureAltitude = altitude;
         }
 
+        CLength CAircraftSituation::getDistancePerTime(const CTime &time) const
+        {
+            if (this->getGroundSpeed().isNull()) { return CLength(0, CLengthUnit::nullUnit()); }
+            const int ms = time.valueInteger(CTimeUnit::ms());
+            return this->getDistancePerTime(ms);
+        }
+
+        CLength CAircraftSituation::getDistancePerTime(int milliseconds) const
+        {
+            if (this->getGroundSpeed().isNull()) { return CLength(0, CLengthUnit::nullUnit()); }
+            const double seconds = milliseconds / 1000;
+            const double gsMeterSecond = this->getGroundSpeed().value(CSpeedUnit::m_s());
+            const CLength d(seconds * gsMeterSecond, CLengthUnit::m());
+            return d;
+        }
+
         void CAircraftSituation::setCallsign(const CCallsign &callsign)
         {
             m_correspondingCallsign = callsign;
diff --git a/src/blackmisc/aviation/aircraftsituation.h b/src/blackmisc/aviation/aircraftsituation.h
index 39ace5c7e..8225c3e1d 100644
--- a/src/blackmisc/aviation/aircraftsituation.h
+++ b/src/blackmisc/aviation/aircraftsituation.h
@@ -23,6 +23,7 @@
 #include "blackmisc/pq/angle.h"
 #include "blackmisc/pq/length.h"
 #include "blackmisc/pq/speed.h"
+#include "blackmisc/pq/time.h"
 #include "blackmisc/propertyindex.h"
 #include "blackmisc/timestampbased.h"
 #include "blackmisc/valueobject.h"
@@ -169,6 +170,9 @@ namespace BlackMisc
             //! Elevation of the ground directly beneath
             void setGroundElevation(const CAltitude &elevation) { m_groundElevation = elevation; }
 
+            //! Set elevation of the ground directly beneath, but checked
+            void setGroundElevationChecked(const CAltitude &elevation, bool ignoreNullValues = true, bool overrideExisting = true);
+
             //! Height above ground.
             PhysicalQuantities::CLength getHeightAboveGround() const;
 
@@ -182,7 +186,7 @@ namespace BlackMisc
             const CAltitude &getAltitude() const { return m_position.geodeticHeight(); }
 
             //! Get altitude under consideration of ground elevation
-            CAltitude getCorrectedAltitude(const PhysicalQuantities::CLength &centerOfGravity = {}) const;
+            CAltitude getCorrectedAltitude(const PhysicalQuantities::CLength &centerOfGravity = {}, bool *corrected = nullptr) const;
 
             //! Set altitude
             void setAltitude(const CAltitude &altitude) { m_position.setGeodeticHeight(altitude); }
@@ -211,6 +215,12 @@ namespace BlackMisc
             //! Set ground speed
             void setGroundSpeed(const PhysicalQuantities::CSpeed &groundspeed) { m_groundSpeed = groundspeed; }
 
+            //! Distance per time
+            PhysicalQuantities::CLength getDistancePerTime(const PhysicalQuantities::CTime &time) const;
+
+            //! Distance per milliseconds
+            PhysicalQuantities::CLength getDistancePerTime(int milliseconds) const;
+
             //! Corresponding callsign
             const CCallsign &getCallsign() const { return m_correspondingCallsign; }
 
@@ -243,7 +253,7 @@ namespace BlackMisc
 
         private:
             CCallsign m_correspondingCallsign;
-            Geo::CCoordinateGeodetic m_position;
+            Geo::CCoordinateGeodetic m_position; // NULL position
             Aviation::CAltitude m_pressureAltitude { 0, nullptr };
             CHeading m_heading;
             PhysicalQuantities::CAngle m_pitch;
diff --git a/src/blackmisc/aviation/altitude.cpp b/src/blackmisc/aviation/altitude.cpp
index 3441b08bd..77d532d75 100644
--- a/src/blackmisc/aviation/altitude.cpp
+++ b/src/blackmisc/aviation/altitude.cpp
@@ -28,6 +28,13 @@ namespace BlackMisc
             this->parseFromString(altitudeAsString, mode);
         }
 
+        CAltitude CAltitude::withOffset(const CLength &offset) const
+        {
+            CAltitude copy(*this);
+            if (!offset.isNull() && !offset.isZeroEpsilonConsidered()) { copy += offset; }
+            return copy;
+        }
+
         QString CAltitude::convertToQString(bool i18n) const
         {
             if (this->m_datum == FlightLevel)
diff --git a/src/blackmisc/aviation/altitude.h b/src/blackmisc/aviation/altitude.h
index dd68ab381..f5e9955da 100644
--- a/src/blackmisc/aviation/altitude.h
+++ b/src/blackmisc/aviation/altitude.h
@@ -100,6 +100,11 @@ namespace BlackMisc
             //! Constructor by CLength
             CAltitude(const PhysicalQuantities::CLength &altitude, ReferenceDatum datum) : CLength(altitude), m_datum(datum) {}
 
+            //! Altitude with offset
+            //! \remark null offset adds nothing
+            //! \remark epsilon 0 (zero) values ignored
+            CAltitude withOffset(const CLength &offset) const;
+
             //! AGL Above ground level?
             bool isAboveGroundLevel() const { return AboveGround == this->m_datum; }
 
diff --git a/src/blackmisc/aviation/callsignset.cpp b/src/blackmisc/aviation/callsignset.cpp
index 0ba10d51e..1859987f6 100644
--- a/src/blackmisc/aviation/callsignset.cpp
+++ b/src/blackmisc/aviation/callsignset.cpp
@@ -26,6 +26,11 @@ namespace BlackMisc
             CCollection<CCallsign>(other)
         { }
 
+        bool CCallsignSet::containsCallsign(const QString &callsign) const
+        {
+            return this->contains(CCallsign(callsign));
+        }
+
         QStringList CCallsignSet::getCallsignStrings(bool sorted) const
         {
             QStringList callsigns;
diff --git a/src/blackmisc/aviation/callsignset.h b/src/blackmisc/aviation/callsignset.h
index cdafed6a1..508bf320c 100644
--- a/src/blackmisc/aviation/callsignset.h
+++ b/src/blackmisc/aviation/callsignset.h
@@ -38,6 +38,9 @@ namespace BlackMisc
             //! Construct from a base class object.
             CCallsignSet(const CCollection<CCallsign> &other);
 
+            //! Contains by string
+            bool containsCallsign(const QString &callsign) const;
+
             //! The callsign strings
             QStringList getCallsignStrings(bool sorted = false) const;
 
diff --git a/src/blackmisc/geo/elevationplane.cpp b/src/blackmisc/geo/elevationplane.cpp
index e073073dd..8903a58ab 100644
--- a/src/blackmisc/geo/elevationplane.cpp
+++ b/src/blackmisc/geo/elevationplane.cpp
@@ -42,7 +42,7 @@ namespace BlackMisc
         {
             if (isNull()) { return false; }
             const CLength d = this->calculateGreatCircleDistance(coordinate);
-            const bool inRange = m_radius >= d;
+            const bool inRange = (m_radius >= d);
             return inRange;
         }
 
@@ -88,9 +88,12 @@ namespace BlackMisc
             }
         }
 
+        // 100km/h 27,8m/s
+        //  50km/h 13,9m/s
+        // 100kts  51,4m/s
         const CLength &CElevationPlane::singlePointRadius()
         {
-            static const CLength l(10.0, CLengthUnit::m());
+            static const CLength l(25.0, CLengthUnit::m());
             return l;
         }
 
diff --git a/src/blackmisc/geo/elevationplane.h b/src/blackmisc/geo/elevationplane.h
index 45752ea07..ab164e933 100644
--- a/src/blackmisc/geo/elevationplane.h
+++ b/src/blackmisc/geo/elevationplane.h
@@ -27,29 +27,32 @@ namespace BlackMisc
             //! Properties by index
             enum ColumnIndex
             {
-                IndexRadius = BlackMisc::CPropertyIndex::GlobalIndexCElevationPlane
+                IndexRadius = CPropertyIndex::GlobalIndexCElevationPlane
             };
 
             //! Default constructor
             CElevationPlane() {}
 
-            //! Constructor
+            //! Constructors from CCoordinateGeodetic
             using CValueObject<CElevationPlane, CCoordinateGeodetic>::CValueObject;
 
             //! Radius
-            const BlackMisc::PhysicalQuantities::CLength &getRadius() const { return m_radius; }
+            const PhysicalQuantities::CLength &getRadius() const { return m_radius; }
 
             //! Radius
-            void setRadius(const BlackMisc::PhysicalQuantities::CLength &radius) { m_radius = radius; }
+            void setRadius(const PhysicalQuantities::CLength &radius) { m_radius = radius; }
 
             //! Altitude when within radius, else null
             const Aviation::CAltitude &getAltitudeIfWithinRadius(const ICoordinateGeodetic &coordinate) const;
 
+            //! Altitude (synonym for geodetic height)
+            const Aviation::CAltitude &getAltitude() const { return this->geodeticHeight(); }
+
             //! Existing value
             bool isNull() const;
 
             //! Check if elevation is within radius and can be used
-            bool isWithinRange(const BlackMisc::Geo::ICoordinateGeodetic &coordinate) const;
+            bool isWithinRange(const ICoordinateGeodetic &coordinate) const;
 
             //! Treat as single point as obtained from simulator
             void setSinglePointRadius();
@@ -61,25 +64,25 @@ namespace BlackMisc
             void setMajorAirportRadius();
 
             //! \copydoc BlackMisc::Mixin::Index::propertyByIndex
-            CVariant propertyByIndex(const BlackMisc::CPropertyIndex &index) const;
+            CVariant propertyByIndex(const CPropertyIndex &index) const;
 
             //! \copydoc BlackMisc::Mixin::Index::setPropertyByIndex
-            void setPropertyByIndex(const BlackMisc::CPropertyIndex &index, const CVariant &variant);
+            void setPropertyByIndex(const CPropertyIndex &index, const CVariant &variant);
 
             //! \copydoc BlackMisc::Mixin::String::toQString
             QString convertToQString(bool i18n = false) const;
 
             //! Radius for single point
-            static const BlackMisc::PhysicalQuantities::CLength &singlePointRadius();
+            static const PhysicalQuantities::CLength &singlePointRadius();
 
             //! Radius for minor airport
-            static const BlackMisc::PhysicalQuantities::CLength &minorAirportRadius();
+            static const PhysicalQuantities::CLength &minorAirportRadius();
 
             //! Radius for major airport
-            static const BlackMisc::PhysicalQuantities::CLength &majorAirportRadius();
+            static const PhysicalQuantities::CLength &majorAirportRadius();
 
         private:
-            BlackMisc::PhysicalQuantities::CLength m_radius { 0, nullptr }; //!< elevation is valid in radius
+            PhysicalQuantities::CLength m_radius { 0, nullptr }; //!< elevation is valid in radius
 
             BLACK_METACLASS(
                 CElevationPlane,