diff --git a/src/blackmisc/aviation/aircraftsituationchange.cpp b/src/blackmisc/aviation/aircraftsituationchange.cpp
index dc35934bb..895dc0f0d 100644
--- a/src/blackmisc/aviation/aircraftsituationchange.cpp
+++ b/src/blackmisc/aviation/aircraftsituationchange.cpp
@@ -88,6 +88,18 @@ namespace BlackMisc
             return !m_guessedSceneryDeviation.isNull();
         }
 
+        bool CAircraftSituationChange::hasElevationDevWithinAllowedRange() const
+        {
+            if (m_elvStdDev.isNull()) { return false; }
+            return m_elvStdDev < allowedAltitudeDeviation();
+        }
+
+        bool CAircraftSituationChange::hasAltitudeDevWithinAllowedRange() const
+        {
+            if (m_altStdDev.isNull()) { return false; }
+            return m_altStdDev < allowedAltitudeDeviation();
+        }
+
         QString CAircraftSituationChange::convertToQString(bool i18n) const
         {
             Q_UNUSED(i18n);
@@ -270,6 +282,12 @@ namespace BlackMisc
             return noInfo;
         }
 
+        const CLength &CAircraftSituationChange::allowedAltitudeDeviation()
+        {
+            static const CLength allowedStdDev(3, CLengthUnit::ft());
+            return allowedStdDev;
+        }
+
         void CAircraftSituationChange::setSceneryDeviation(const CLength &deviation, const CLength &cg, CAircraftSituationChange::GuessedSceneryDeviation hint)
         {
             m_guessedSceneryDeviation = deviation;
diff --git a/src/blackmisc/aviation/aircraftsituationchange.h b/src/blackmisc/aviation/aircraftsituationchange.h
index 42d2f9d7a..24c7500fd 100644
--- a/src/blackmisc/aviation/aircraftsituationchange.h
+++ b/src/blackmisc/aviation/aircraftsituationchange.h
@@ -16,13 +16,13 @@
 #include "altitude.h"
 #include "blackmisc/pq/angle.h"
 #include "blackmisc/pq/speed.h"
+#include "blackmisc/pair.h"
 #include "blackmisc/metaclass.h"
 #include "blackmisc/timestampbased.h"
 #include "blackmisc/valueobject.h"
 #include "blackmisc/variant.h"
-#include "blackmisc/blackmiscexport.h"
 #include "blackmisc/propertyindex.h"
-#include <QPair>
+#include "blackmisc/blackmiscexport.h"
 
 namespace BlackMisc
 {
@@ -119,22 +119,22 @@ namespace BlackMisc
 
             //! Ground distance (AGL) if it can be calculated, otherwise NULL
             //! \note distance is without CG, so on ground it can also be used to calculate
-            QPair<PhysicalQuantities::CLength, PhysicalQuantities::CLength> getGroundDistanceStdDevAndMean() const { return QPair<PhysicalQuantities::CLength, PhysicalQuantities::CLength>(m_gndDistStdDev, m_gndDistMean); }
+            PhysicalQuantities::CLengthPair getGroundDistanceStdDevAndMean() const { return PhysicalQuantities::CLengthPair(m_gndDistStdDev, m_gndDistMean); }
 
             //! \copydoc BlackMisc::Aviation::CAircraftSituationList::altitudeStandardDeviationAndMean
-            QPair<CAltitude, CAltitude> getAltitudeStdDevAndMean() const { return QPair<CAltitude, CAltitude>(m_altStdDev, m_altMean); }
+            CAltitudePair getAltitudeStdDevAndMean() const { return CAltitudePair(m_altStdDev, m_altMean); }
 
             //! \copydoc BlackMisc::Aviation::CAircraftSituationList::elevationStandardDeviationAndMean
-            QPair<CAltitude, CAltitude> getElevationStdDevAndMean() const { return QPair<CAltitude, CAltitude>(m_elvStdDev, m_elvMean); }
+            CAltitudePair getElevationStdDevAndMean() const { return CAltitudePair(m_elvStdDev, m_elvMean); }
 
             //! \copydoc BlackMisc::Aviation::CAircraftSituationList::groundSpeedStandardDeviationAndMean
-            QPair<PhysicalQuantities::CSpeed, PhysicalQuantities::CSpeed> getGroundSpeedStdDevAndMean() const { return QPair<PhysicalQuantities::CSpeed, PhysicalQuantities::CSpeed>(m_gsStdDev, m_gsMean); }
+            PhysicalQuantities::CSpeedPair getGroundSpeedStdDevAndMean() const { return PhysicalQuantities::CSpeedPair(m_gsStdDev, m_gsMean); }
 
             //! \copydoc BlackMisc::Aviation::CAircraftSituationList::pitchStandardDeviationAndMean
-            QPair<PhysicalQuantities::CAngle, PhysicalQuantities::CAngle> getPitchStdDevAndMean() const { return QPair<PhysicalQuantities::CAngle, PhysicalQuantities::CAngle>(m_pitchStdDev, m_pitchMean); }
+            PhysicalQuantities::CAnglePair getPitchStdDevAndMean() const { return PhysicalQuantities::CAnglePair(m_pitchStdDev, m_pitchMean); }
 
             //! \copydoc BlackMisc::Aviation::CAircraftSituationList::minMaxGroundDistance
-            QPair<PhysicalQuantities::CLength, PhysicalQuantities::CLength> getMinMaxGroundDistance() const { return QPair<PhysicalQuantities::CLength, PhysicalQuantities::CLength>(m_minGroundDistance, m_maxGroundDistance); }
+            PhysicalQuantities::CLengthPair getMinMaxGroundDistance() const { return PhysicalQuantities::CLengthPair(m_minGroundDistance, m_maxGroundDistance); }
 
             //! Scnenery deviation (if it can be calculated, otherwise PhysicalQuantities::CLength::null)
             //! This is without CG, so substract CG to get deviation
@@ -152,6 +152,12 @@ namespace BlackMisc
             //! Scenery deviation available?
             bool hasSceneryDeviation() const;
 
+            //! Elevation within CAircraftSituation::allowedAltitudeDeviation range
+            bool hasElevationDevWithinAllowedRange() const;
+
+            //! Altitude within CAircraftSituation::allowedAltitudeDeviation range
+            bool hasAltitudeDevWithinAllowedRange() const;
+
             //! \copydoc Mixin::String::toQString
             QString convertToQString(bool i18n = false) const;
 
@@ -173,6 +179,9 @@ namespace BlackMisc
             //! The enum as string
             static const QString &guessedSceneryDeviationToString(GuessedSceneryDeviation hint);
 
+            //! Within this range deviation is so small we consider values "almost constant"
+            static const PhysicalQuantities::CLength &allowedAltitudeDeviation();
+
         private:
             //! Scenery deviation hint
             void setSceneryDeviationHint(GuessedSceneryDeviation hint) { m_guessedSceneryDeviationHint = static_cast<int>(hint); }
diff --git a/src/blackmisc/aviation/aircraftsituationlist.cpp b/src/blackmisc/aviation/aircraftsituationlist.cpp
index ab3226996..f7eeda704 100644
--- a/src/blackmisc/aviation/aircraftsituationlist.cpp
+++ b/src/blackmisc/aviation/aircraftsituationlist.cpp
@@ -452,36 +452,36 @@ namespace BlackMisc
             return values;
         }
 
-        QPair<CSpeed, CSpeed> CAircraftSituationList::groundSpeedStandardDeviationAndMean() const
+        CSpeedPair CAircraftSituationList::groundSpeedStandardDeviationAndMean() const
         {
             const QList<double> gsValues = this->groundSpeedValues(CSpeedUnit::kts());
             if (gsValues.size() != this->size()) { return QPair<CSpeed, CSpeed>(CSpeed::null(), CSpeed::null()); }
             const QPair<double, double> gsKts = CMathUtils::standardDeviationAndMean(gsValues);
-            return QPair<CSpeed, CSpeed>(CSpeed(gsKts.first, CSpeedUnit::kts()), CSpeed(gsKts.second, CSpeedUnit::kts()));
+            return CSpeedPair(CSpeed(gsKts.first, CSpeedUnit::kts()), CSpeed(gsKts.second, CSpeedUnit::kts()));
         }
 
-        QPair<CAngle, CAngle> CAircraftSituationList::pitchStandardDeviationAndMean() const
+        CAnglePair CAircraftSituationList::pitchStandardDeviationAndMean() const
         {
             const QList<double> pitchValues = this->pitchValues(CAngleUnit::deg());
             if (pitchValues.size() != this->size()) { return QPair<CAngle, CAngle>(CAngle::null(), CAngle::null()); }
             const QPair<double, double> pitchDeg = CMathUtils::standardDeviationAndMean(pitchValues);
-            return QPair<CAngle, CAngle>(CAngle(pitchDeg.first, CAngleUnit::deg()), CAngle(pitchDeg.second, CAngleUnit::deg()));
+            return CAnglePair(CAngle(pitchDeg.first, CAngleUnit::deg()), CAngle(pitchDeg.second, CAngleUnit::deg()));
         }
 
-        QPair<CAltitude, CAltitude> CAircraftSituationList::elevationStandardDeviationAndMean() const
+        CAltitudePair CAircraftSituationList::elevationStandardDeviationAndMean() const
         {
             const QList<double> elvValues = this->elevationValues(CAltitude::defaultUnit());
-            if (elvValues.size() != this->size()) { return QPair<CAltitude, CAltitude>(CAltitude::null(), CAltitude::null()); }
+            if (elvValues.size() != this->size()) { return CAltitudePair(CAltitude::null(), CAltitude::null()); }
             const QPair<double, double> elvFt = CMathUtils::standardDeviationAndMean(elvValues);
-            return QPair<CAltitude, CAltitude>(CAltitude(elvFt.first, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()), CAltitude(elvFt.second, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()));
+            return CAltitudePair(CAltitude(elvFt.first, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()), CAltitude(elvFt.second, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()));
         }
 
-        QPair<CAltitude, CAltitude> CAircraftSituationList::altitudeStandardDeviationAndMean() const
+        CAltitudePair CAircraftSituationList::altitudeStandardDeviationAndMean() const
         {
             const QList<double> altValues = this->altitudeValues(CAltitude::defaultUnit());
-            if (altValues.size() != this->size()) { return QPair<CAltitude, CAltitude>(CAltitude::null(), CAltitude::null()); }
+            if (altValues.size() != this->size()) { return CAltitudePair(CAltitude::null(), CAltitude::null()); }
             const QPair<double, double> altFt = CMathUtils::standardDeviationAndMean(altValues);
-            return QPair<CAltitude, CAltitude>(CAltitude(altFt.first, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()), CAltitude(altFt.second, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()));
+            return CAltitudePair(CAltitude(altFt.first, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()), CAltitude(altFt.second, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()));
         }
 
         QPair<CLength, CLength> CAircraftSituationList::minMaxGroundDistance(const CLength &cg) const
@@ -494,13 +494,13 @@ namespace BlackMisc
             return QPair<CLength, CLength>(CLength(gndDistMin, CAltitude::defaultUnit()), CLength(gndDistMax, CAltitude::defaultUnit()));
         }
 
-        QPair<CAltitude, CAltitude> CAircraftSituationList::altitudeAglStandardDeviationAndMean() const
+        CAltitudePair CAircraftSituationList::altitudeAglStandardDeviationAndMean() const
         {
             const QList<double> altValues = this->altitudeValues(CLengthUnit::ft());
-            if (altValues.size() != this->size()) { return QPair<CAltitude, CAltitude>(CAltitude::null(), CAltitude::null()); }
+            if (altValues.size() != this->size()) { return CAltitudePair(CAltitude::null(), CAltitude::null()); }
 
             const QList<double> elvValues = this->elevationValues(CLengthUnit::ft());
-            if (elvValues.size() != this->size()) { return QPair<CAltitude, CAltitude>(CAltitude::null(), CAltitude::null()); }
+            if (elvValues.size() != this->size()) { return CAltitudePair(CAltitude::null(), CAltitude::null()); }
 
             QList<double> altElvDeltas;
             for (int i = 0; i < altValues.size(); i++)
@@ -509,7 +509,8 @@ namespace BlackMisc
                 altElvDeltas.push_back(delta);
             }
             const QPair<double, double> deltaFt = CMathUtils::standardDeviationAndMean(altElvDeltas);
-            return QPair<CAltitude, CAltitude>(CAltitude(deltaFt.first, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()), CAltitude(deltaFt.second, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()));
+            return CAltitudePair(CAltitude(deltaFt.first, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()), CAltitude(deltaFt.second, CAltitude::MeanSeaLevel, CAltitude::defaultUnit()));
+        }
         }
     } // namespace
 } // namespace
diff --git a/src/blackmisc/aviation/aircraftsituationlist.h b/src/blackmisc/aviation/aircraftsituationlist.h
index 2a65a04b7..cbed8833a 100644
--- a/src/blackmisc/aviation/aircraftsituationlist.h
+++ b/src/blackmisc/aviation/aircraftsituationlist.h
@@ -20,6 +20,7 @@
 #include "blackmisc/collection.h"
 #include "blackmisc/sequence.h"
 #include "blackmisc/timestampobjectlist.h"
+#include "blackmisc/pair.h"
 #include "blackmisc/variant.h"
 
 #include <QMetaType>
@@ -164,23 +165,23 @@ namespace BlackMisc
             QList<double> groundDistanceValues(const PhysicalQuantities::CLengthUnit &unit, const PhysicalQuantities::CLength &cg) const;
 
             //! Pitch angles standard deviation and mean
-            QPair<PhysicalQuantities::CAngle, PhysicalQuantities::CAngle> pitchStandardDeviationAndMean() const;
+            PhysicalQuantities::CAnglePair pitchStandardDeviationAndMean() const;
 
             //! Ground speed standard deviation and mean
-            QPair<PhysicalQuantities::CSpeed, PhysicalQuantities::CSpeed> groundSpeedStandardDeviationAndMean() const;
+            PhysicalQuantities::CSpeedPair groundSpeedStandardDeviationAndMean() const;
 
             //! Elevation standard deviation and mean
-            QPair<CAltitude, CAltitude> elevationStandardDeviationAndMean() const;
+            CAltitudePair elevationStandardDeviationAndMean() const;
 
             //! Elevation standard deviation and mean
-            QPair<CAltitude, CAltitude> altitudeStandardDeviationAndMean() const;
-
-            //! Min. and max. ground distance
-            QPair<PhysicalQuantities::CLength, PhysicalQuantities::CLength> minMaxGroundDistance(const PhysicalQuantities::CLength &cg) const;
+            CAltitudePair altitudeStandardDeviationAndMean() const;
 
             //! Elevation standard deviation and mean
             //! \note distance is without CG, so on ground it can also be used to calculate
-            QPair<CAltitude, CAltitude> altitudeAglStandardDeviationAndMean() const;
+            CAltitudePair altitudeAglStandardDeviationAndMean() const;
+
+            //! Min. and max. ground distance
+            PhysicalQuantities::CLengthPair minMaxGroundDistance(const PhysicalQuantities::CLength &cg) const;
         };
 
         //! Situation per callsign
diff --git a/src/blackmisc/pair.h b/src/blackmisc/pair.h
new file mode 100644
index 000000000..7700dc52e
--- /dev/null
+++ b/src/blackmisc/pair.h
@@ -0,0 +1,43 @@
+/* Copyright (C) 2018
+ * Swift Project Community / Contributors
+ *
+ * This file is part of Swift Project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
+ * including this file, may be copied, modified, propagated, or distributed except according to the terms
+ * contained in the LICENSE file.
+ */
+
+//! \file
+
+#ifndef BLACKMISC_PAIR_H
+#define BLACKMISC_PAIR_H
+
+#include "blackmisc/aviation/altitude.h"
+#include "blackmisc/pq/angle.h"
+#include "blackmisc/pq/length.h"
+#include "blackmisc/pq/speed.h"
+#include "blackmisc/variant.h"
+
+#include <QPair>
+#include <QDBusMetaType>
+
+namespace BlackMisc
+{
+    namespace PhysicalQuantities
+    {
+        using CAnglePair = QPair<CAngle, CAngle>;     //!< Pair of angle
+        using CLengthPair = QPair<CLength, CLength>;  //!< Pair of length
+        using CSpeedPair = QPair<CSpeed, CSpeed>;     //!< Pair of speed
+    }
+    namespace Aviation
+    {
+        using CAltitudePair = QPair<CAltitude, CAltitude>; //!< Pair of altitude
+    }
+} // namespace
+
+Q_DECLARE_METATYPE(BlackMisc::PhysicalQuantities::CAnglePair)
+Q_DECLARE_METATYPE(BlackMisc::PhysicalQuantities::CLengthPair)
+Q_DECLARE_METATYPE(BlackMisc::PhysicalQuantities::CSpeedPair)
+Q_DECLARE_METATYPE(BlackMisc::Aviation::CAltitudePair)
+
+#endif // guard