diff --git a/src/blackmisc/simulation/interpolant.h b/src/blackmisc/simulation/interpolant.h
index 7df9233c4..09966e2e5 100644
--- a/src/blackmisc/simulation/interpolant.h
+++ b/src/blackmisc/simulation/interpolant.h
@@ -17,9 +17,6 @@ namespace BlackMisc::Simulation
         //! "Real time" representing the interpolated situation
         qint64 getInterpolatedTime() const { return m_interpolatedTime; }
 
-        //! Interpolator for pitch, bank, heading, groundspeed
-        const CInterpolatorPbh &pbh() const { return m_pbh; }
-
         //! Situations available
         int getSituationsAvailable() const { return m_situationsAvailable; }
 
@@ -37,17 +34,16 @@ namespace BlackMisc::Simulation
 
     protected:
         //! Default ctor
-        IInterpolant() {}
+        IInterpolant() = default;
 
         //! Constructor
-        IInterpolant(int situationsAvailable, const CInterpolatorPbh &pbh) : m_situationsAvailable(situationsAvailable), m_pbh(pbh) {}
+        explicit IInterpolant(int situationsAvailable) : m_situationsAvailable(situationsAvailable) {}
 
         //! Constructor
         IInterpolant(qint64 interpolatedTime, int situationsAvailable) : m_interpolatedTime(interpolatedTime), m_situationsAvailable(situationsAvailable) {}
 
         qint64 m_interpolatedTime = -1; //!< "Real time "of interpolated situation
         int m_situationsAvailable = 0; //!< used situations
-        CInterpolatorPbh m_pbh; //!< the used PBH interpolator
         bool m_valid = true; //!< valid?
         bool m_recalculated = false; //!< recalculated interpolant
     };
diff --git a/src/blackmisc/simulation/interpolator.cpp b/src/blackmisc/simulation/interpolator.cpp
index 708118d32..1343f5cd7 100644
--- a/src/blackmisc/simulation/interpolator.cpp
+++ b/src/blackmisc/simulation/interpolator.cpp
@@ -245,12 +245,12 @@ namespace BlackMisc::Simulation
         do
         {
             if (!isValidInterpolant) { break; }
-            const CInterpolatorPbh pbh = interpolant.pbh();
 
             // init interpolated situation
             currentSituation = this->initInterpolatedSituation(pbh.getStartSituation(), pbh.getEndSituation());
 
             // Pitch bank heading first, so follow up steps could use those values
+            const auto pbh = interpolant.pbh();
             currentSituation.setHeading(pbh.getHeading());
             currentSituation.setPitch(pbh.getPitch());
             currentSituation.setBank(pbh.getBank());
diff --git a/src/blackmisc/simulation/interpolatorlinear.cpp b/src/blackmisc/simulation/interpolatorlinear.cpp
index 31fbd0c46..df4f6c261 100644
--- a/src/blackmisc/simulation/interpolatorlinear.cpp
+++ b/src/blackmisc/simulation/interpolatorlinear.cpp
@@ -23,12 +23,12 @@ using namespace BlackMisc::Simulation;
 
 namespace BlackMisc::Simulation
 {
-    CInterpolatorLinear::CInterpolant::CInterpolant(const CAircraftSituation &startSituation) : IInterpolant(1, CInterpolatorPbh(0, startSituation, startSituation)),
-                                                                                                m_startSituation(startSituation)
+    CInterpolatorLinear::CInterpolant::CInterpolant(const CAircraftSituation &startSituation) : IInterpolant(1),
+                                                                                                m_startSituation(startSituation), m_pbh(0, startSituation, startSituation)
     {}
 
-    CInterpolatorLinear::CInterpolant::CInterpolant(const CAircraftSituation &startSituation, const CInterpolatorPbh &pbh) : IInterpolant(1, pbh),
-                                                                                                                             m_startSituation(startSituation)
+    CInterpolatorLinear::CInterpolant::CInterpolant(const CAircraftSituation &startSituation, const CInterpolatorPbh &pbh) : IInterpolant(1),
+                                                                                                                             m_startSituation(startSituation), m_pbh(pbh)
     {}
 
     CInterpolatorLinear::CInterpolant::CInterpolant(const CAircraftSituation &startSituation, const CAircraftSituation &endSituation, double timeFraction, qint64 interpolatedTime) : IInterpolant(interpolatedTime, 2),
diff --git a/src/blackmisc/simulation/interpolatorlinear.h b/src/blackmisc/simulation/interpolatorlinear.h
index ebc504f57..d2148fbc2 100644
--- a/src/blackmisc/simulation/interpolatorlinear.h
+++ b/src/blackmisc/simulation/interpolatorlinear.h
@@ -60,10 +60,13 @@ namespace BlackMisc
                 //! End situation
                 const Aviation::CAircraftSituation &getEndSituation() const { return m_endSituation; }
 
+                CInterpolatorPbh pbh() const { return m_pbh; }
+
             private:
                 Aviation::CAircraftSituation m_startSituation;
                 Aviation::CAircraftSituation m_endSituation;
                 double m_simulationTimeFraction = 0.0; //!< 0..1
+                CInterpolatorPbh m_pbh;
             };
 
             //! Get the interpolant for the given time point
diff --git a/src/blackmisc/simulation/interpolatorspline.h b/src/blackmisc/simulation/interpolatorspline.h
index c25690c8e..f86d3a217 100644
--- a/src/blackmisc/simulation/interpolatorspline.h
+++ b/src/blackmisc/simulation/interpolatorspline.h
@@ -77,10 +77,13 @@ namespace BlackMisc::Simulation
             //! \private UNIT tests/ASSERT only
             const PosArray &getPa() const { return m_pa; }
 
+            CInterpolatorPbh pbh() const { return m_pbh; }
+
         private:
             PosArray m_pa; //!< current positions array, latest values last
             PhysicalQuantities::CLengthUnit m_altitudeUnit;
             qint64 m_currentTimeMsSinceEpoc { -1 };
+            CInterpolatorPbh m_pbh; //!< the used PBH interpolator
         };
 
         //! Strategy used by CInterpolator::getInterpolatedSituation