diff --git a/src/blackmisc/geo/geoobjectlist.cpp b/src/blackmisc/geo/geoobjectlist.cpp
index b8c3d00e2..ceae36ecc 100644
--- a/src/blackmisc/geo/geoobjectlist.cpp
+++ b/src/blackmisc/geo/geoobjectlist.cpp
@@ -133,6 +133,20 @@ namespace BlackMisc
             return stats;
         }
 
+        template<class OBJ, class CONTAINER>
+        CAltitude IGeoObjectList<OBJ, CONTAINER>::findMaxHeight() const
+        {
+            if (this->container().isEmpty()) { return CAltitude::null(); }
+            CAltitude max = CAltitude::null();
+            for (const OBJ &obj : this->container())
+            {
+                if (!obj.hasMSLGeodeticHeight()) { continue; }
+                const CAltitude alt = obj.geodeticHeight();
+                if (max.isNull() || alt > max) { max = alt; }
+            }
+            return max;
+        }
+
         template <class OBJ, class CONTAINER>
         int IGeoObjectList<OBJ, CONTAINER>::removeOutsideRange(const ICoordinateGeodetic &coordinate, const PhysicalQuantities::CLength &range)
         {
diff --git a/src/blackmisc/geo/geoobjectlist.h b/src/blackmisc/geo/geoobjectlist.h
index ce0e2419e..5cbab4024 100644
--- a/src/blackmisc/geo/geoobjectlist.h
+++ b/src/blackmisc/geo/geoobjectlist.h
@@ -83,6 +83,9 @@ namespace BlackMisc
             //! Find min/max/average height
             MinMaxAverageHeight findMinMaxAverageHeight() const;
 
+            //! Find min/max/average height
+            Aviation::CAltitude findMaxHeight() const;
+
             //! Remove outside range
             int removeOutsideRange(const ICoordinateGeodetic &coordinate, const PhysicalQuantities::CLength &range);
 
diff --git a/src/blackmisc/simulation/simulationenvironmentprovider.cpp b/src/blackmisc/simulation/simulationenvironmentprovider.cpp
index a58131b53..716705109 100644
--- a/src/blackmisc/simulation/simulationenvironmentprovider.cpp
+++ b/src/blackmisc/simulation/simulationenvironmentprovider.cpp
@@ -173,6 +173,13 @@ namespace BlackMisc
             return coordinates.averageGeodeticHeight(reference, range, CAircraftSituationChange::allowedAltitudeDeviation(), minValues);
         }
 
+        CAltitude ISimulationEnvironmentProvider::highestElevation() const
+        {
+            const CCoordinateGeodeticList coordinates = this->getElevationCoordinatesOnGround();
+            if (coordinates.isEmpty()) { return CAltitude::null(); }
+            return coordinates.findMaxHeight();
+        }
+
         CCoordinateGeodeticList ISimulationEnvironmentProvider::getAllElevationCoordinates(int &maxRemembered) const
         {
             QReadLocker l(&m_lockElvCoordinates);
@@ -392,6 +399,60 @@ namespace BlackMisc
             m_elvFound = m_elvMissed        =  0;
         }
 
+        bool ISimulationEnvironmentProvider::cleanElevationValues(const CAircraftSituation &reference, const CLength &range, bool forced)
+        {
+            if (reference.isNull() || range.isNull()) { return false; }
+            const CLength r = minRange(range);
+
+            CCoordinateGeodeticList elvs;
+            CCoordinateGeodeticList cleanedElvs;
+            bool maxReached = false;
+            bool cleaned    = false;
+
+            {
+                QReadLocker l(&m_lockElvCoordinates);
+                elvs = m_elvCoordinates;
+                maxReached = m_elvCoordinates.size() >= m_maxElevations;
+            }
+            if (!elvs.isEmpty() && (forced || maxReached))
+            {
+                for (const CAircraftSituation &s : elvs)
+                {
+                    if (s.isWithinRange(reference, r)) { cleanedElvs.push_back(s); }
+                }
+
+                if (cleanedElvs.size() < elvs.size())
+                {
+                    cleaned = true;
+                    QWriteLocker l(&m_lockElvCoordinates);
+                    m_elvCoordinates = cleanedElvs;
+                }
+            }
+
+            cleanedElvs.clear();
+            {
+                QReadLocker l(&m_lockElvCoordinates);
+                elvs = m_elvCoordinatesGnd;
+                maxReached = m_elvCoordinatesGnd.size() >= m_maxElevationsGnd;
+            }
+            if (!elvs.isEmpty() && (forced || maxReached))
+            {
+                for (const CAircraftSituation &s : elvs)
+                {
+                    if (s.isWithinRange(reference, r)) { cleanedElvs.push_back(s); }
+                }
+
+                if (cleanedElvs.size() < elvs.size())
+                {
+                    cleaned = true;
+                    QWriteLocker l(&m_lockElvCoordinates);
+                    m_elvCoordinatesGnd = cleanedElvs;
+                }
+            }
+
+            return cleaned;
+        }
+
         ISimulationEnvironmentProvider::ISimulationEnvironmentProvider(const CSimulatorPluginInfo &pluginInfo) :
             m_simulatorPluginInfo(pluginInfo)
         { }
@@ -529,6 +590,12 @@ namespace BlackMisc
             return this->provider()->averageElevationOfOnGroundAircraft(reference, range, minValues);
         }
 
+        CAltitude CSimulationEnvironmentAware::highestElevation() const
+        {
+            if (!this->hasProvider()) { return CAltitude::null(); }
+            return this->provider()->highestElevation();
+        }
+
         bool CSimulationEnvironmentAware::requestElevation(const ICoordinateGeodetic &reference, const CCallsign &callsign)
         {
             if (!this->hasProvider()) { return false; }
@@ -605,5 +672,11 @@ namespace BlackMisc
             if (!this->hasProvider()) { return false; }
             return this->provider()->hasSimulatorCG(callsign);
         }
+
+        bool CSimulationEnvironmentAware::cleanElevationValues(const CAircraftSituation &reference, const CLength &range, bool forced)
+        {
+            if (!this->hasProvider()) { return false; }
+            return this->provider()->cleanElevationValues(reference, range, forced);
+        }
     } // namespace
 } // namespace
diff --git a/src/blackmisc/simulation/simulationenvironmentprovider.h b/src/blackmisc/simulation/simulationenvironmentprovider.h
index 65b3ce068..0906cdb03 100644
--- a/src/blackmisc/simulation/simulationenvironmentprovider.h
+++ b/src/blackmisc/simulation/simulationenvironmentprovider.h
@@ -134,6 +134,10 @@ namespace BlackMisc
             //! \threadsafe
             void resetSimulationEnvironmentStatistics();
 
+            //! Average elevation of "on ground" cached values
+            //! \threadsafe
+            bool cleanElevationValues(const Aviation::CAircraftSituation &reference, const PhysicalQuantities::CLength &range, bool forced = false);
+
         protected:
             //! Ctor
             ISimulationEnvironmentProvider(const CSimulatorPluginInfo &pluginInfo);
@@ -296,6 +300,9 @@ namespace BlackMisc
             //! \copydoc ISimulationEnvironmentProvider::averageElevationOfOnGroundAircraft
             Geo::CElevationPlane averageElevationOfOnGroundAircraft(const Aviation::CAircraftSituation &reference, const PhysicalQuantities::CLength &range, int minValues) const;
 
+            //! \copydoc ISimulationEnvironmentProvider::highestElevation
+            Aviation::CAltitude highestElevation() const;
+
             //! \copydoc ISimulationEnvironmentProvider::requestElevation
             bool requestElevation(const Geo::ICoordinateGeodetic &reference, const Aviation::CCallsign &callsign);
 
@@ -335,6 +342,9 @@ namespace BlackMisc
             //! \copydoc ISimulationEnvironmentProvider::hasSimulatorCG
             bool hasSimulatorCG(const Aviation::CCallsign &callsign) const;
 
+            //! \copydoc ISimulationEnvironmentProvider::cleanElevationValues
+            bool cleanElevationValues(const Aviation::CAircraftSituation &reference, const PhysicalQuantities::CLength &range, bool forced = false);
+
         protected:
             //! Default constructor
             CSimulationEnvironmentAware() {}