diff --git a/src/blackcore/airspacemonitor.cpp b/src/blackcore/airspacemonitor.cpp
index d8f7c3111..192e1c9bd 100644
--- a/src/blackcore/airspacemonitor.cpp
+++ b/src/blackcore/airspacemonitor.cpp
@@ -1288,10 +1288,11 @@ namespace BlackCore
         // list from new to old
         QWriteLocker lock(&m_lockSituations);
         CAircraftSituationList &situationList = m_situationsByCallsign[callsign];
-        situationList.push_frontMaxElements(situation, MaxSituationsPerCallsign);
+        situationList.push_frontMaxElements(situation, IRemoteAircraftProvider::MaxSituationsPerCallsign);
 
         // check sort order
-        Q_ASSERT_X(situationList.size() < 2 || situationList[0].getMSecsSinceEpoch() >= situationList[1].getMSecsSinceEpoch(), Q_FUNC_INFO, "wrong sort order");
+        Q_ASSERT_X(situationList.isSortedAdjustedLatestFirst(), Q_FUNC_INFO, "wrong sort order");
+        Q_ASSERT_X(situationList.size() <= IRemoteAircraftProvider::MaxSituationsPerCallsign, Q_FUNC_INFO, "Wrong size");
     }
 
     void CAirspaceMonitor::storeAircraftParts(const CCallsign &callsign, const CAircraftParts &parts)
@@ -1311,7 +1312,8 @@ namespace BlackCore
         m_aircraftSupportingParts.insert(callsign); // mark as callsign which supports parts
 
         // check sort order
-        Q_ASSERT_X(partsList.size() < 2 || partsList[0].getMSecsSinceEpoch() >= partsList[1].getMSecsSinceEpoch(), Q_FUNC_INFO, "wrong sort order");
+        Q_ASSERT_X(partsList.isSortedAdjustedLatestFirst(), Q_FUNC_INFO, "wrong sort order");
+        Q_ASSERT_X(partsList.size() <= IRemoteAircraftProvider::MaxPartsPerCallsign, Q_FUNC_INFO, "Wrong size");
     }
 
     void CAirspaceMonitor::sendInitialAtcQueries(const CCallsign &callsign)
diff --git a/src/blackmisc/simulation/interpolator.cpp b/src/blackmisc/simulation/interpolator.cpp
index 7c85143c5..01ee6e159 100644
--- a/src/blackmisc/simulation/interpolator.cpp
+++ b/src/blackmisc/simulation/interpolator.cpp
@@ -236,9 +236,15 @@ namespace BlackMisc
                 return emptyParts;
             }
 
-            // find the first parts not in the correct order, keep only the parts before that one
-            const auto end = std::is_sorted_until(m_aircraftParts.begin(), m_aircraftParts.end(), [](auto && a, auto && b) { return b.getAdjustedMSecsSinceEpoch() < a.getAdjustedMSecsSinceEpoch(); });
-            const auto validParts = makeRange(m_aircraftParts.begin(), end);
+            // with the latest updates of T243 the order and the offsets are supposed to be correct
+            // so even mixing fast/slow updates shall work
+            Q_ASSERT_X(m_aircraftParts.isSortedAdjustedLatestFirst(), Q_FUNC_INFO, "Wrong sort order");
+
+            // Ref T243, KB 2018-02, can be removed in future, we verify parts above
+            // Parts are supposed to be in correct order
+            // const auto end = std::is_sorted_until(m_aircraftParts.begin(), m_aircraftParts.end(), [](auto && a, auto && b) { return b.getAdjustedMSecsSinceEpoch() < a.getAdjustedMSecsSinceEpoch(); });
+            // const auto validParts = makeRange(m_aircraftParts.begin(), end);
+            const CAircraftPartsList &validParts = m_aircraftParts;
 
             // stop if we don't have any parts
             if (validParts.isEmpty()) { return {}; }
diff --git a/src/blackmisc/simulation/interpolatorlinear.cpp b/src/blackmisc/simulation/interpolatorlinear.cpp
index 2c7986df7..b1a918fc0 100644
--- a/src/blackmisc/simulation/interpolatorlinear.cpp
+++ b/src/blackmisc/simulation/interpolatorlinear.cpp
@@ -17,6 +17,7 @@
 #include "blackmisc/simulation/interpolationhints.h"
 #include "blackmisc/logmessage.h"
 #include "blackmisc/compare.h"
+#include "blackmisc/verify.h"
 #include "blackmisc/range.h"
 #include "blackmisc/sequence.h"
 #include "blackmisc/statusmessage.h"
@@ -55,12 +56,18 @@ namespace BlackMisc
             Q_UNUSED(hints);
             status.reset();
 
-            // find the first situation not in the correct order, keep only the situations before that one
-            // any updates in wrong chronological order are discounted
-            const auto end = std::is_sorted_until(m_aircraftSituations.begin(), m_aircraftSituations.end(), [](auto && a, auto && b) { return b.getAdjustedMSecsSinceEpoch() < a.getAdjustedMSecsSinceEpoch(); });
-            const auto validSituations = makeRange(m_aircraftSituations.begin(), end);
+            // with the latest updates of T243 the order and the offsets are supposed to be correct
+            // so even mixing fast/slow updates shall work
+            BLACK_VERIFY_X(m_aircraftSituations.isSortedAdjustedLatestFirst(), Q_FUNC_INFO, "Wrong sort order");
+            Q_ASSERT_X(m_aircraftSituations.size() <= IRemoteAircraftProvider::MaxSituationsPerCallsign, Q_FUNC_INFO, "Wrong size");
+
+            // Ref T243, KB 2018-02, can be removed in future, we verify situations above
+            // Situations are supposed to be in correct order
+            // const auto end = std::is_sorted_until(m_aircraftSituations.begin(), m_aircraftSituations.end(), [](auto && a, auto && b) { return b.getAdjustedMSecsSinceEpoch() < a.getAdjustedMSecsSinceEpoch(); });
+            // const auto validSituations = makeRange(m_aircraftSituations.begin(), end);
 
             // find the first situation earlier than the current time
+            const CAircraftSituationList &validSituations = m_aircraftSituations; // if needed, we could also copy here
             const auto pivot = std::partition_point(validSituations.begin(), validSituations.end(), [ = ](auto && s) { return s.getAdjustedMSecsSinceEpoch() > currentTimeMsSinceEpoc; });
             const auto situationsNewer = makeRange(validSituations.begin(), pivot);
             const auto situationsOlder = makeRange(pivot, validSituations.end());
diff --git a/src/blackmisc/simulation/interpolatorspline.cpp b/src/blackmisc/simulation/interpolatorspline.cpp
index 867cf3f30..3ee7da5ab 100644
--- a/src/blackmisc/simulation/interpolatorspline.cpp
+++ b/src/blackmisc/simulation/interpolatorspline.cpp
@@ -10,6 +10,7 @@
 #include "blackmisc/simulation/interpolatorspline.h"
 #include "blackmisc/simulation/interpolationhints.h"
 #include "blackmisc/logmessage.h"
+#include "blackmisc/verify.h"
 
 using namespace BlackMisc::Aviation;
 using namespace BlackMisc::Geo;
@@ -104,15 +105,18 @@ namespace BlackMisc
             // recalculate derivatives only if they changed
             if (currentTimeMsSinceEpoc > m_nextSampleAdjustedTime)
             {
-                // find the first situation not in the correct order, keep only the situations before that one
-                //! \todo KB 2-2018, IMHO the sorting by adjusted times is wrong. we should sort by received time
-                // when mixing fast/slow updates, the postion is represented when it is sent, not when it is used
-                // see example below
-                // so why do we check here only, and do not sort
-                const auto end = std::is_sorted_until(m_aircraftSituations.begin(), m_aircraftSituations.end(), [](auto && a, auto && b) { return b.getAdjustedMSecsSinceEpoch() < a.getAdjustedMSecsSinceEpoch(); });
-                const auto validSituations = makeRange(m_aircraftSituations.begin(), end);
+                // with the latest updates of T243 the order and the offsets are supposed to be correct
+                // so even mixing fast/slow updates shall work
+                Q_ASSERT_X(m_aircraftSituations.isSortedAdjustedLatestFirst(), Q_FUNC_INFO, "Wrong sort order");
+                Q_ASSERT_X(m_aircraftSituations.size() <= IRemoteAircraftProvider::MaxSituationsPerCallsign, Q_FUNC_INFO, "Wrong size");
+
+                // Ref T243, KB 2018-02, can be removed in future, we verify situations above
+                // Situations are supposed to be in correct order
+                // const auto end = std::is_sorted_until(m_aircraftSituations.begin(), m_aircraftSituations.end(), [](auto && a, auto && b) { return b.getAdjustedMSecsSinceEpoch() < a.getAdjustedMSecsSinceEpoch(); });
+                // const auto validSituations = makeRange(m_aircraftSituations.begin(), end);
 
                 // find the first situation earlier than the current time
+                const CAircraftSituationList &validSituations = m_aircraftSituations; // if needed, we could also copy here
                 const auto pivot = std::partition_point(validSituations.begin(), validSituations.end(), [ = ](auto && s) { return s.getAdjustedMSecsSinceEpoch() > currentTimeMsSinceEpoc; });
                 const auto situationsNewer = makeRange(validSituations.begin(), pivot);
                 const auto situationsOlder = makeRange(pivot, validSituations.end());