diff --git a/src/blackmisc/aviation/aircraftcategory.cpp b/src/blackmisc/aviation/aircraftcategory.cpp
index 376aeb1d8..d14edb504 100644
--- a/src/blackmisc/aviation/aircraftcategory.cpp
+++ b/src/blackmisc/aviation/aircraftcategory.cpp
@@ -83,6 +83,15 @@ namespace BlackMisc
             m_l3 = l3;
         }
 
+        QList<int> CAircraftCategory::getLevel() const
+        {
+            QList<int> l;
+            if (m_l1 > 0) l << m_l1;
+            if (m_l2 > 0) l << m_l2;
+            if (m_l3 > 0) l << m_l3;
+            return l;
+        }
+
         bool CAircraftCategory::isFirstLevel() const
         {
             return (m_l3 == 0 && m_l2 == 0 && m_l1 > 0);
@@ -110,6 +119,23 @@ namespace BlackMisc
             return stringCompare(path, this->getPath(), cs);
         }
 
+        bool CAircraftCategory::matchesLevel(int l1, int l2, int l3) const
+        {
+            if (l1 != m_l1) { return false; }
+            if (l2 > 0 && l2 != m_l2) { return false; }
+            if (l3 > 0 && l3 != m_l3) { return false; }
+            return true;
+        }
+
+        bool CAircraftCategory::matchesLevel(const QList<int> &level) const
+        {
+            if (level.isEmpty()) { return false; }
+            const int l1 = level.first();
+            const int l2 = level.size() > 1 ? level.at(1) : 0;
+            const int l3 = level.size() > 2 ? level.at(2) : 0;
+            return this->matchesLevel(l1, l2, l3);
+        }
+
         CVariant CAircraftCategory::propertyByIndex(const BlackMisc::CPropertyIndex &index) const
         {
             if (index.isMyself()) { return CVariant::from(*this); }
@@ -184,5 +210,11 @@ namespace BlackMisc
             c = Compare::compare(m_l3, other.m_l3);
             return c;
         }
+
+        bool CAircraftCategory::isHigherLevel(const CAircraftCategory &other) const
+        {
+            const int c = this->compareByLevel(other);
+            return c < 0;
+        }
     } // namespace
 } // namespace
diff --git a/src/blackmisc/aviation/aircraftcategory.h b/src/blackmisc/aviation/aircraftcategory.h
index ebde8966a..30e2238ec 100644
--- a/src/blackmisc/aviation/aircraftcategory.h
+++ b/src/blackmisc/aviation/aircraftcategory.h
@@ -21,6 +21,7 @@
 
 #include <QJsonObject>
 #include <QMap>
+#include <QList>
 #include <QStringList>
 #include <QMetaType>
 
@@ -77,6 +78,9 @@ namespace BlackMisc
             //! Level
             void setLevel(int l1, int l2, int l3);
 
+            //! Levels depending on depth, 3.2 -> 3,2 / 1.0 -> 1 / 4.3.1 -> 4,3,1
+            QList<int> getLevel() const;
+
             //! First level
             int getFirstLevel() const { return m_l1; }
 
@@ -95,6 +99,12 @@ namespace BlackMisc
             //! Matching path?
             bool matchesPath(const QString &path, Qt::CaseSensitivity cs);
 
+            //! Is matching the level, 0 ignored
+            bool matchesLevel(int l1, int l2 = 0, int l3 = 0) const;
+
+            //! Is matching the level, 0 ignored
+            bool matchesLevel(const QList<int> &level) const;
+
             //! Assignable?
             bool isAssignable() const { return m_assignable; }
 
@@ -122,6 +132,9 @@ namespace BlackMisc
             //! Level compare
             int compareByLevel(const CAircraftCategory &other) const;
 
+            //! Higher level?
+            bool isHigherLevel(const CAircraftCategory &other) const;
+
             //! NULL object
             static const CAircraftCategory &null();
 
diff --git a/src/blackmisc/aviation/aircraftcategorylist.cpp b/src/blackmisc/aviation/aircraftcategorylist.cpp
index 66ef2f8d2..5e0470a83 100644
--- a/src/blackmisc/aviation/aircraftcategorylist.cpp
+++ b/src/blackmisc/aviation/aircraftcategorylist.cpp
@@ -12,6 +12,7 @@
 #include <QJsonObject>
 #include <QJsonValue>
 #include <Qt>
+#include <QMap>
 
 namespace BlackMisc
 {
@@ -68,12 +69,57 @@ namespace BlackMisc
             return ll;
         }
 
+        CAircraftCategoryList CAircraftCategoryList::findHighestLevels(const CAircraftCategoryList &categories)
+        {
+            if (categories.isEmpty()) { return CAircraftCategoryList(); }
+            QMap<int, CAircraftCategory> highestLevels;
+            for (const CAircraftCategory &category : *this)
+            {
+                const int fl = category.getFirstLevel();
+                if (highestLevels.contains(fl))
+                {
+                    if (highestLevels[fl].isHigherLevel(category))
+                    {
+                        highestLevels[fl] = category;
+                    }
+                }
+                else
+                {
+                    highestLevels[fl] = category;
+                }
+            }
+
+            CAircraftCategoryList topLevels;
+            for (const CAircraftCategory &category : highestLevels.values())
+            {
+                topLevels.push_back(category);
+            }
+            return topLevels;
+        }
+
         CAircraftCategoryList CAircraftCategoryList::findByFirstLevel(int level) const
         {
             CAircraftCategoryList categories;
             for (const CAircraftCategory &category : *this)
             {
-                if (category.getFirstLevel() != level) { continue; }
+                if (category.getFirstLevel() == level)
+                {
+                    categories.push_back(category);
+                }
+            }
+            return categories;
+        }
+
+        CAircraftCategoryList CAircraftCategoryList::findByLevel(const QList<int> &level) const
+        {
+            CAircraftCategoryList categories;
+            if (level.isEmpty()) { return categories; }
+            for (const CAircraftCategory &category : *this)
+            {
+                if (category.matchesLevel(level))
+                {
+                    categories.push_back(category);
+                }
             }
             return categories;
         }
@@ -83,6 +129,45 @@ namespace BlackMisc
             return this->findBy(&CAircraftCategory::isFirstLevel, true);
         }
 
+        CAircraftCategoryList CAircraftCategoryList::findSiblings(const CAircraftCategory &category) const
+        {
+            QList<int> levels = category.getLevel();
+            CAircraftCategoryList categories;
+            if (levels.size() < 2)
+            {
+                categories = this->findFirstLevels();
+            }
+            else
+            {
+                levels.removeLast();
+                categories = this->findByLevel(levels);
+            }
+            categories.remove(category);
+            return categories;
+        }
+
+        int CAircraftCategoryList::removeIfLevel(const QList<int> &level)
+        {
+            if (level.isEmpty()) { return 0; }
+            const int c = this->size();
+            const CAircraftCategoryList removed = this->removedLevel(level);
+            const int delta = c - removed.size();
+            if (delta > 0) { *this = removed; }
+            return delta;
+        }
+
+        CAircraftCategoryList CAircraftCategoryList::removedLevel(const QList<int> &level) const
+        {
+            if (level.isEmpty()) { return *this; } // nothing removed
+            CAircraftCategoryList removed;
+            for (const CAircraftCategory &category : * this)
+            {
+                if (category.matchesLevel(level)) { continue; }
+                removed.push_back(category);
+            }
+            return removed;
+        }
+
         CAircraftCategoryList CAircraftCategoryList::fromDatabaseJson(const QJsonArray &array)
         {
             CAircraftCategoryList categories;
diff --git a/src/blackmisc/aviation/aircraftcategorylist.h b/src/blackmisc/aviation/aircraftcategorylist.h
index d7ccada16..1a5c1e725 100644
--- a/src/blackmisc/aviation/aircraftcategorylist.h
+++ b/src/blackmisc/aviation/aircraftcategorylist.h
@@ -21,6 +21,7 @@
 #include <QJsonArray>
 #include <QMetaType>
 #include <QSet>
+#include <QList>
 #include <tuple>
 
 namespace BlackMisc
@@ -57,12 +58,28 @@ namespace BlackMisc
             //! All levels sorted
             QList<int> getFirstLevels() const;
 
+            //! Find highest (top) level of categories
+            CAircraftCategoryList findHighestLevels(const CAircraftCategoryList &categories);
+
             //! Find by first level
             CAircraftCategoryList findByFirstLevel(int level) const;
 
+            //! Find by levels
+            CAircraftCategoryList findByLevel(const QList<int> &level) const;
+
             //! Find first levels
             CAircraftCategoryList findFirstLevels() const;
 
+            //! Find siblings
+            //! \remark if level is 3.2, siblings are 3.1 and 3.3
+            CAircraftCategoryList findSiblings(const CAircraftCategory &category) const;
+
+            //! Remove by level
+            int removeIfLevel(const QList<int> &level);
+
+            //! With removed categories
+            CAircraftCategoryList removedLevel(const QList<int> &level) const;
+
             //! From our database JSON format
             static CAircraftCategoryList fromDatabaseJson(const QJsonArray &array);
         };