diff --git a/src/blackmisc/dbusutils.cpp b/src/blackmisc/dbusutils.cpp
index c369af754..7d3c1beaf 100644
--- a/src/blackmisc/dbusutils.cpp
+++ b/src/blackmisc/dbusutils.cpp
@@ -75,6 +75,7 @@ namespace BlackMisc
         const CAirportIcaoCode airportIcao;
         const CLivery livery;
         const CAirport airport;
+        const CAircraftSituation situation;
         const CSimulatedAircraft aircraft;
         const CSimulatedAircraftList aircraftList;
         const CVariant var;
@@ -89,6 +90,8 @@ namespace BlackMisc
         out << "CAirportIcaoCode" << " size: " << s.size() << " sig: " << s << endl;
         s = CDBusUtils::dBusSignature(livery);
         out << "CLivery" << " size: " << s.size() << " sig: " << s << endl;
+        s = CDBusUtils::dBusSignature(situation);
+        out << "CAircraftSituation" << " size: " << s.size() << " sig: " << s << endl;
         s = CDBusUtils::dBusSignature(country);
         out << "CCountry" << " size: " << s.size() << " sig: " << s << endl;
         s = CDBusUtils::dBusSignature(airport);
diff --git a/src/blackmisc/dbusutils.h b/src/blackmisc/dbusutils.h
index 6fb3509fc..548649818 100644
--- a/src/blackmisc/dbusutils.h
+++ b/src/blackmisc/dbusutils.h
@@ -34,6 +34,13 @@ namespace BlackMisc
             return arg.currentSignature();
         }
 
+        //! Signature size for BlackMisc::CValueObject
+        template<typename ValueObj>
+        static int dBusSignatureSize(const ValueObj &obj)
+        {
+            return dBusSignature<ValueObj>(obj).size();
+        }
+
         //! Type as string
         static QString dbusTypeAsString(QDBusArgument::ElementType type);
 
diff --git a/tests/blackcore/testblackcoremain.h b/tests/blackcore/testblackcoremain.h
index e5e39e2e3..7659be8f1 100644
--- a/tests/blackcore/testblackcoremain.h
+++ b/tests/blackcore/testblackcoremain.h
@@ -30,7 +30,7 @@ namespace BlackCoreTest
         //! Unit tests
         static int unitMain(int argc, char *argv[]);
     };
-}
+} // ns
 
 //! \endcond
 
diff --git a/tests/blackcore/testcontext.cpp b/tests/blackcore/testcontext.cpp
index 1e90a2028..4a88280d4 100644
--- a/tests/blackcore/testcontext.cpp
+++ b/tests/blackcore/testcontext.cpp
@@ -16,8 +16,13 @@
 
 #include "testcontext.h"
 #include "blackcore/context/contextallproxies.h"
+#include "blackmisc/simulation/simulatedaircraftlist.h"
+#include "blackmisc/dbusutils.h"
 #include <QTest>
 
+using namespace BlackMisc;
+using namespace BlackMisc::Aviation;
+using namespace BlackMisc::Simulation;
 using namespace BlackCore::Context;
 
 namespace BlackCoreTest
@@ -37,6 +42,27 @@ namespace BlackCoreTest
         CContextOwnAircraftProxy::unitTestRelaySignals();
         CContextSimulatorProxy::unitTestRelaySignals();
     }
-}
+
+    void CTestContext::dBusSignatures()
+    {
+        const CAircraftModel model;
+        const CAircraftSituation situation;
+        const CSimulatedAircraft aircraft;
+        const CSimulatedAircraftList aircraftList;
+
+        constexpr int MaxSize = 210;
+        int s = CDBusUtils::dBusSignatureSize(model);
+        QVERIFY2(s < MaxSize, "CAircraftModel");
+
+        s = CDBusUtils::dBusSignatureSize(situation);
+        QVERIFY2(s < MaxSize, "CAircraftSituation");
+
+        s = CDBusUtils::dBusSignatureSize(aircraft);
+        QVERIFY2(s < MaxSize, "CSimulatedAircraft");
+
+        s = CDBusUtils::dBusSignatureSize(aircraftList);
+        QVERIFY2(s < MaxSize, "CSimulatedAircraftList");
+    }
+} // ns
 
 //! \endcond
diff --git a/tests/blackcore/testcontext.h b/tests/blackcore/testcontext.h
index f46762e9c..411106b2f 100644
--- a/tests/blackcore/testcontext.h
+++ b/tests/blackcore/testcontext.h
@@ -34,6 +34,9 @@ namespace BlackCoreTest
     private slots:
         //! Init tests for context
         void contextInitTest();
+
+        //! Test the DBus signatures
+        void dBusSignatures();
     };
 } //namespace
 
diff --git a/tests/blackmisc/testaircraftsituation.cpp b/tests/blackmisc/testaircraftsituation.cpp
new file mode 100644
index 000000000..9ecad17fb
--- /dev/null
+++ b/tests/blackmisc/testaircraftsituation.cpp
@@ -0,0 +1,179 @@
+/* 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.
+ */
+
+//! \cond PRIVATE_TESTS
+
+/*!
+ * \file
+ * \ingroup testblackmisc
+ */
+
+#include "testaircraftsituation.h"
+#include "blackmisc/aviation/aircraftsituationchange.h"
+#include "blackmisc/math/mathutils.h"
+#include "blackcore/vatsim/networkvatlib.h"
+
+#include <QTest>
+#include <QDateTime>
+
+using namespace BlackMisc::Aviation;
+using namespace BlackMisc::PhysicalQuantities;
+using namespace BlackMisc::Geo;
+using namespace BlackMisc::Math;
+using namespace BlackCore::Vatsim;
+
+namespace BlackMiscTest
+{
+    CTestAircraftSituation::CTestAircraftSituation(QObject *parent): QObject(parent)
+    {
+        // void
+    }
+
+    void CTestAircraftSituation::allGndFlagsAndTakeOff() const
+    {
+        CAircraftSituationList situations = testSituations();
+        situations.setOnGround(CAircraftSituation::OnGround);
+        const CAircraftSituationChange change(situations);
+        QVERIFY2(change.isConstOnGround(), "Expect const on ground");
+        QVERIFY(!change.isConstNotOnGround());
+        QVERIFY(!change.isJustTakingOff());
+        QVERIFY(!change.isJustTouchingDown());
+        QVERIFY(change.wasConstOnGround());
+        QVERIFY(!change.wasConstNotOnGround());
+        QVERIFY(situations.isSortedAdjustedLatestFirstWithoutNullPositions());
+
+        CAircraftSituation f = situations.front();
+        f.setOnGround(false);
+        situations.pop_front();
+        situations.push_front(f);
+        const CAircraftSituationChange change2(situations);
+        QVERIFY2(change2.isJustTakingOff(), "Expect just take off");
+        QVERIFY(!change2.isJustTouchingDown());
+        QVERIFY(change.wasConstOnGround());
+        QVERIFY(!change.wasConstNotOnGround());
+    }
+
+    void CTestAircraftSituation::allNotGndFlagsAndTouchdown() const
+    {
+        CAircraftSituationList situations = testSetDescendingAltitudes(testSituations());
+        situations.setOnGround(CAircraftSituation::NotOnGround);
+        const CAircraftSituationChange change(situations);
+        QVERIFY2(change.isConstNotOnGround(), "Expect const not on ground");
+        QVERIFY(!change.isConstOnGround());
+        QVERIFY(!change.isJustTakingOff());
+        QVERIFY(!change.isJustTouchingDown());
+        QVERIFY(!change.wasConstOnGround());
+        QVERIFY(change.wasConstNotOnGround());
+        QVERIFY(situations.isSortedAdjustedLatestFirstWithoutNullPositions());
+
+        CAircraftSituation f = situations.front();
+        f.setOnGround(true);
+        situations.pop_front();
+        situations.push_front(f);
+        const CAircraftSituationChange change2(situations);
+        QVERIFY2(change2.isJustTouchingDown(), "Expect just touchdown");
+        QVERIFY(!change2.isJustTakingOff());
+        QVERIFY(!change.wasConstOnGround());
+        QVERIFY(change.wasConstNotOnGround());
+    }
+
+    void CTestAircraftSituation::ascending()
+    {
+        const CAircraftSituationList situations = testSituations();
+        QVERIFY2(situations.isConstAscending(), "Expect ascending");
+    }
+
+    void CTestAircraftSituation::descending()
+    {
+        const CAircraftSituationList situations = testSetDescendingAltitudes(testSituations());
+        QVERIFY2(situations.isConstDescending(), "Expect descending");
+    }
+
+    void CTestAircraftSituation::rotateUp()
+    {
+        CAircraftSituationList situations = testSetRotateUpPitch(testSituations());
+        const CAircraftSituationChange change(situations);
+        QVERIFY2(!change.isRotatingUp(), "Do not expect rotate up");
+
+        CAircraftSituation f = situations.front();
+        situations.pop_front();
+        f.setPitch(CAngle(7.3, CAngleUnit::deg()));
+        situations.push_front(f);
+
+        const CAircraftSituationChange change2(situations);
+        QVERIFY2(change2.isRotatingUp(), "Expect rotate up");
+    }
+
+    void CTestAircraftSituation::sortOrder() const
+    {
+        CAircraftSituationList situations = testSituations();
+        QVERIFY2(situations.isSortedAdjustedLatestFirstWithoutNullPositions(), "Expect latest first");
+        QVERIFY(!situations.isSortedLatestLast());
+
+        situations.reverse();
+        QVERIFY2(situations.isSortedAdjustedLatestLast(), "Expect latest first");
+        QVERIFY(!situations.isSortedAdjustedLatestFirst());
+    }
+
+    CAircraftSituationList CTestAircraftSituation::testSituations()
+    {
+        // "Kugaaruk Airport","Pelly Bay","Canada","YBB","CYBB",68.534401,-89.808098,56,-7,"A","America/Edmonton","airport","OurAirports"
+        // "Baie Comeau Airport","Baie Comeau","Canada","YBC","CYBC",49.13249969482422,-68.20439910888672,71,-5,"A","America/Toronto","airport","OurAirports"
+        // "CFB Bagotville","Bagotville","Canada","YBG","CYBG",48.33060073852539,-70.99639892578125,522,-5,"A","America/Toronto","airport","OurAirports"
+
+        CAircraftSituationList situations;
+        qint64 ts = QDateTime::currentSecsSinceEpoch();
+        qint64 os = CFsdSetup::c_positionTimeOffsetMsec;
+        CAltitude alt(10000, CAltitude::MeanSeaLevel, CLengthUnit::m());
+        static const CCoordinateGeodetic dummyPos(48.33060073852539, -70.99639892578125, 522);
+
+        for (int i = 0; i < 10; i++)
+        {
+            CAircraftSituation s(dummyPos);
+            const qint64 cTs = ts - i * os;
+            s.setMSecsSinceEpoch(cTs);
+            s.setTimeOffsetMs(os);
+            CAltitude altitude(alt);
+            altitude.addValueSameUnit(-100 * i); // 10000, 9900, 9800 .... (newer->older)
+            s.setAltitude(altitude);
+            situations.push_back(s);
+        }
+        return situations;
+    }
+
+    CAircraftSituationList CTestAircraftSituation::testSetDescendingAltitudes(const CAircraftSituationList &situations)
+    {
+        CAircraftSituationList newSituations;
+        CAltitude alt(0, CAltitude::MeanSeaLevel, CLengthUnit::m());
+
+        for (const CAircraftSituation &situation : situations)
+        {
+            CAircraftSituation s(situation);
+            s.setAltitude(alt);
+            newSituations.push_back(s);
+            alt.addValueSameUnit(100); // 0, 100, 200 ... (newer->older)
+        }
+        return newSituations;
+    }
+
+    CAircraftSituationList CTestAircraftSituation::testSetRotateUpPitch(const CAircraftSituationList &situations)
+    {
+        CAircraftSituationList newSituations;
+        for (const CAircraftSituation &situation : situations)
+        {
+            CAircraftSituation s(situation);
+            const double pitch = CMathUtils::randomDouble(1.5);
+            s.setPitch(CAngle(pitch, CAngleUnit::deg()));
+            newSituations.push_back(s);
+        }
+        return newSituations;
+    }
+} // namespace
+
+//! \endcond
diff --git a/tests/blackmisc/testaircraftsituation.h b/tests/blackmisc/testaircraftsituation.h
new file mode 100644
index 000000000..f07aed191
--- /dev/null
+++ b/tests/blackmisc/testaircraftsituation.h
@@ -0,0 +1,69 @@
+/* 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.
+ */
+
+#ifndef BLACKMISCTEST_TESTAIRCRAFTSITUATION_H
+#define BLACKMISCTEST_TESTAIRCRAFTSITUATION_H
+
+//! \cond PRIVATE_TESTS
+
+/*!
+ * \file
+ * \ingroup testblackmisc
+ */
+
+#include "blackmisc/aviation/aircraftsituationlist.h"
+#include <QObject>
+
+namespace BlackMiscTest
+{
+    /*!
+     * CAircraftSituation and CAircraftSituationChange tests
+     */
+    class CTestAircraftSituation : public QObject
+    {
+        Q_OBJECT
+
+    public:
+        //! Standard test case constructor
+        explicit CTestAircraftSituation(QObject *parent = nullptr);
+
+    private slots:
+        //! All GND flags
+        void allGndFlagsAndTakeOff() const;
+
+        //! All not GND flags
+        void allNotGndFlagsAndTouchdown() const;
+
+        //! Ascending aircraft
+        void ascending();
+
+        //! Descending aircraft
+        void descending();
+
+        //! Rotating up aircraft
+        void rotateUp();
+
+        //! Test sort order
+        void sortOrder() const;
+
+    private:
+        //! Test situations (ascending)
+        static BlackMisc::Aviation::CAircraftSituationList testSituations();
+
+        //! Set descending altitudes
+        static BlackMisc::Aviation::CAircraftSituationList testSetDescendingAltitudes(const BlackMisc::Aviation::CAircraftSituationList &situations);
+
+        //! Set descending altitudes
+        static BlackMisc::Aviation::CAircraftSituationList testSetRotateUpPitch(const BlackMisc::Aviation::CAircraftSituationList &situations);
+    };
+} // namespace
+
+//! \endcond
+
+#endif // guard
diff --git a/tests/blackmisc/testaviation.cpp b/tests/blackmisc/testaviation.cpp
index f798b603a..34a0ded04 100644
--- a/tests/blackmisc/testaviation.cpp
+++ b/tests/blackmisc/testaviation.cpp
@@ -201,6 +201,25 @@ namespace BlackMiscTest
         QCOMPARE(qRound(altitude2.value(CLengthUnit::m())), 510);
     }
 
+    void CTestAviation::testGuessing()
+    {
+        const CAircraftIcaoCode icao172("C172", "L1P");
+        const CAircraftIcaoCode icaoB737("B737", "L2J");
+        const CAircraftIcaoCode icaoB747("B747", "L4J");
+
+        CSpeed s172, sB737, sB747; s172 = sB737 = sB747 = CSpeed::null();
+        CLength cg172, cgB737, cgB747; cg172 = cgB737 = cgB747 = CLength::null();
+        icao172.guessModelParameters(cg172, s172);
+        icaoB737.guessModelParameters(cgB737, sB737);
+        icaoB747.guessModelParameters(cgB747, sB747);
+
+        QVERIFY(cg172 < cgB737);
+        QVERIFY(cgB737 < cgB747);
+
+        QVERIFY(s172 < sB747);
+        QVERIFY(sB737 < sB747);
+    }
+
 } // namespace
 
 //! \endcond
diff --git a/tests/blackmisc/testaviation.h b/tests/blackmisc/testaviation.h
index 2e9351517..a425e0cc8 100644
--- a/tests/blackmisc/testaviation.h
+++ b/tests/blackmisc/testaviation.h
@@ -50,6 +50,9 @@ namespace BlackMiscTest
 
         //! CAltitude tests
         void altitude();
+
+        //! Test some of the guessing functions
+        void testGuessing();
     };
 } // namespace
 
diff --git a/tests/blackmisc/testblackmiscmain.cpp b/tests/blackmisc/testblackmiscmain.cpp
index 2a9ebbdb1..1fae88029 100644
--- a/tests/blackmisc/testblackmiscmain.cpp
+++ b/tests/blackmisc/testblackmiscmain.cpp
@@ -14,6 +14,7 @@
 #include "testaviation.h"
 #include "testcompress.h"
 #include "testblackmiscmain.h"
+#include "testaircraftsituation.h"
 #include "testcontainers.h"
 #include "testdbus.h"
 #include "testflightplan.h"
@@ -69,6 +70,10 @@ namespace BlackMiscTest
             CTestAircraftParts apTests;
             status |= test.exec(&apTests, "blackmisc_aircraftParts");
         }
+        {
+            CTestAircraftSituation sitTests;
+            status |= test.exec(&sitTests, "blackmisc_aircraftSituation");
+        }
         {
             CTestGeo geoTests;
             status |= test.exec(&geoTests, "blackmisc_geo");
diff --git a/tests/blackmisc/testcontainers.cpp b/tests/blackmisc/testcontainers.cpp
index d0f1b2f08..4f67bb719 100644
--- a/tests/blackmisc/testcontainers.cpp
+++ b/tests/blackmisc/testcontainers.cpp
@@ -43,9 +43,16 @@
 
 using namespace BlackMisc;
 using namespace BlackMisc::Aviation;
+using namespace BlackMisc::Geo;
+using namespace BlackMisc::PhysicalQuantities;
 
 namespace BlackMiscTest
 {
+    void CTestContainers::initTestCase()
+    {
+        BlackMisc::registerMetadata();
+    }
+
     void CTestContainers::collectionBasics()
     {
         CCollection<int> c1;
@@ -132,7 +139,6 @@ namespace BlackMiscTest
 
     void CTestContainers::findTests()
     {
-        BlackMisc::registerMetadata();
         CCallsignSet callsigns;
         CSequence<CCallsign> found = callsigns.findBy(&CCallsign::asString, "Foo");
         QVERIFY2(found.isEmpty(), "Empty found");
@@ -227,7 +233,7 @@ namespace BlackMiscTest
     {
         CAircraftSituationList situations;
         const qint64 ts = QDateTime::currentMSecsSinceEpoch();
-        const int no = 10;
+        int no = 10;
         for (int i = 0; i < no; ++i)
         {
             CAircraftSituation s;
@@ -266,20 +272,46 @@ namespace BlackMiscTest
                 QVERIFY2(situations.front().getMSecsSinceEpoch() == cTs, "Wrong front element");
             }
         }
+
+        situations.sortLatestFirst();
+        QVERIFY2(situations.isSortedLatestFirst(), "Espect sorted latest first");
+        no = situations.size();
+        for (int i = 0; i < no; ++i)
+        {
+            const CAircraftSituation current = situations[i];
+            const qint64 cTs = current.getMSecsSinceEpoch();
+            const CAircraftSituation expectedBefore = situations.findObjectBeforeOrDefault(cTs);
+            const CAircraftSituation expectedAfter = situations.findObjectAfterOrDefault(cTs);
+            const qint64 beforeTs = expectedBefore.getMSecsSinceEpoch();
+            const qint64 afterTs = expectedAfter.getMSecsSinceEpoch();
+
+            if (i > 0)
+            {
+                const qint64 t1 = situations[i - 1].getMSecsSinceEpoch();
+                QVERIFY2(t1 == afterTs, "Wrong expected after");
+            }
+            if (i < (no - 1))
+            {
+                const qint64 t1 = situations[i + 1].getMSecsSinceEpoch();
+                QVERIFY2(t1 == beforeTs, "Wrong expected before");
+            }
+        }
     }
 
     void CTestContainers::offsetTimestampList()
     {
         qsrand(QDateTime::currentDateTime().toTime_t());
         CAircraftSituationList situations;
+        static const CCoordinateGeodetic geoPos = CCoordinateGeodetic::fromWgs84("48° 21′ 13″ N", "11° 47′ 09″ E", { 1487, CLengthUnit::ft() });
         qint64 ts = 1000000;
-        const int no = 10;
+        int no = 10;
         const int max = 6;
         int dt = 0;
 
         for (int i = 0; i < no; ++i)
         {
             CAircraftSituation s;
+            s.setPosition(geoPos);
             s.setMSecsSinceEpoch(ts);
             s.setCallsign("CS" + QString::number(i));
 
@@ -300,10 +332,32 @@ namespace BlackMiscTest
             situations.push_frontKeepLatestFirstAdjustOffset(s, max);
 
             QVERIFY2(situations.size() <= max, "Wrong size");
-            QVERIFY2(situations.isSortedAdjustedLatestFirst(), "Wrong sort order");
+            QVERIFY2(situations.isSortedAdjustedLatestFirstWithoutNullPositions(), "Wrong sort order");
             QVERIFY2(!situations.hasInvalidTimestamps(), "Missing timestamps");
             QVERIFY2(!situations.containsZeroOrNegativeOffsetTime(), "Missing offset time");
         }
+
+        no = situations.size();
+        for (int i = 0; i < no; ++i)
+        {
+            const CAircraftSituation current = situations[i];
+            const qint64 cTs = current.getAdjustedMSecsSinceEpoch();
+            const CAircraftSituation expectedBefore = situations.findObjectBeforeAdjustedOrDefault(cTs);
+            const CAircraftSituation expectedAfter = situations.findObjectAfterAdjustedOrDefault(cTs);
+            const qint64 beforeTs = expectedBefore.getAdjustedMSecsSinceEpoch();
+            const qint64 afterTs = expectedAfter.getAdjustedMSecsSinceEpoch();
+
+            if (i > 0)
+            {
+                const qint64 t1 = situations[i - 1].getAdjustedMSecsSinceEpoch();
+                QVERIFY2(t1 == afterTs, "Wrong expected after");
+            }
+            if (i < (no - 1))
+            {
+                const qint64 t1 = situations[i + 1].getAdjustedMSecsSinceEpoch();
+                QVERIFY2(t1 == beforeTs, "Wrong expected before");
+            }
+        }
     }
 } //namespace
 
diff --git a/tests/blackmisc/testcontainers.h b/tests/blackmisc/testcontainers.h
index d55a82123..87efe63c6 100644
--- a/tests/blackmisc/testcontainers.h
+++ b/tests/blackmisc/testcontainers.h
@@ -28,6 +28,8 @@ namespace BlackMiscTest
         explicit CTestContainers(QObject *parent = nullptr) : QObject(parent) {}
 
     private slots:
+        void initTestCase();
+
         void collectionBasics();
         void sequenceBasics();
         void joinAndSplit();