diff --git a/src/blackmisc/aviation/aircraftpartslist.cpp b/src/blackmisc/aviation/aircraftpartslist.cpp
index 44c11423f..08194b0a6 100644
--- a/src/blackmisc/aviation/aircraftpartslist.cpp
+++ b/src/blackmisc/aviation/aircraftpartslist.cpp
@@ -25,5 +25,17 @@ namespace BlackMisc
         CAircraftPartsList::CAircraftPartsList(std::initializer_list<CAircraftParts> il) :
             CSequence<CAircraftParts>(il)
         { }
+
+        int CAircraftPartsList::setOnGround(bool onGround)
+        {
+            int c = 0;
+            for (CAircraftParts &p : *this)
+            {
+                if (p.isOnGround() == onGround) { continue; }
+                p.setOnGround(onGround);
+                c++;
+            }
+            return c;
+        }
     } // namespace
 } // namespace
diff --git a/src/blackmisc/aviation/aircraftpartslist.h b/src/blackmisc/aviation/aircraftpartslist.h
index 80f31582c..6f7a2b0bc 100644
--- a/src/blackmisc/aviation/aircraftpartslist.h
+++ b/src/blackmisc/aviation/aircraftpartslist.h
@@ -29,7 +29,7 @@ namespace BlackMisc
         class BLACKMISC_EXPORT CAircraftPartsList :
             public CSequence<CAircraftParts>,
             public ITimestampWithOffsetObjectList<CAircraftParts, CAircraftPartsList>,
-            public BlackMisc::Mixin::MetaType<CAircraftPartsList>
+            public Mixin::MetaType<CAircraftPartsList>
         {
         public:
             BLACKMISC_DECLARE_USING_MIXIN_METATYPE(CAircraftPartsList)
@@ -42,8 +42,10 @@ namespace BlackMisc
 
             //! Construct from initializer list.
             CAircraftPartsList(std::initializer_list<CAircraftParts> il);
-        };
 
+            //! Set on ground for all entries
+            int setOnGround(bool onGround);
+        };
     } //namespace
 } // namespace
 
diff --git a/src/blackmisc/timestampbased.cpp b/src/blackmisc/timestampbased.cpp
index d7a135b2a..f8e9cf039 100644
--- a/src/blackmisc/timestampbased.cpp
+++ b/src/blackmisc/timestampbased.cpp
@@ -310,7 +310,7 @@ namespace BlackMisc
         return (i >= static_cast<int>(IndexOffsetMs)) && (i <= static_cast<int>(IndexOffsetWithUnit));
     }
 
-    bool ITimestampWithOffsetBased::hasOffsetTime() const
+    bool ITimestampWithOffsetBased::hasNonZeroOffsetTime() const
     {
         return m_timeOffsetMs != 0;
     }
diff --git a/src/blackmisc/timestampbased.h b/src/blackmisc/timestampbased.h
index 512434a12..943bb773e 100644
--- a/src/blackmisc/timestampbased.h
+++ b/src/blackmisc/timestampbased.h
@@ -162,7 +162,7 @@ namespace BlackMisc
         qint64 getTimeOffsetMs() const { return m_timeOffsetMs; }
 
         //! Having a valid offset time
-        bool hasOffsetTime() const;
+        bool hasNonZeroOffsetTime() const;
 
         //! Offset with unit
         QString getTimeOffsetWithUnit() const;
diff --git a/src/blackmisc/timestampobjectlist.cpp b/src/blackmisc/timestampobjectlist.cpp
index 2af700c96..f078f5a3a 100644
--- a/src/blackmisc/timestampobjectlist.cpp
+++ b/src/blackmisc/timestampobjectlist.cpp
@@ -293,6 +293,16 @@ namespace BlackMisc
         return false;
     }
 
+    template<class OBJ, class CONTAINER>
+    bool ITimestampWithOffsetObjectList<OBJ, CONTAINER>::containsNegativeOffsetTime() const
+    {
+        for (const ITimestampWithOffsetBased &obj : this->container())
+        {
+            if (obj.getTimeOffsetMs() < 0) { return true; }
+        }
+        return false;
+    }
+
     template<class OBJ, class CONTAINER>
     ITimestampWithOffsetObjectList<OBJ, CONTAINER>::ITimestampWithOffsetObjectList() : ITimestampObjectList<OBJ, CONTAINER>()
     {
diff --git a/src/blackmisc/timestampobjectlist.h b/src/blackmisc/timestampobjectlist.h
index abfe95319..5138f5736 100644
--- a/src/blackmisc/timestampobjectlist.h
+++ b/src/blackmisc/timestampobjectlist.h
@@ -128,6 +128,9 @@ namespace BlackMisc
         //! Any negative or zero offset time?
         bool containsZeroOrNegativeOffsetTime() const;
 
+        //! Any negative offset time?
+        bool containsNegativeOffsetTime() const;
+
         //! Insert as first element by keeping maxElements and the latest first
         void push_frontKeepLatestAdjustedFirst(const OBJ &value, int maxElements = -1);