diff --git a/src/blackmisc/simulation/interpolationlogger.cpp b/src/blackmisc/simulation/interpolationlogger.cpp
index f100ff2f0..aa5940450 100644
--- a/src/blackmisc/simulation/interpolationlogger.cpp
+++ b/src/blackmisc/simulation/interpolationlogger.cpp
@@ -302,8 +302,8 @@ namespace BlackMisc
                     u"<th>Interpolation ts.</th><th>Sample &Delta;t</th><th>fraction</th>"
                     u"<th>lat.old</th><th>lat.new</th><th>lat.cur</th>"
                     u"<th>lng.old</th><th>lng.new</th><th>lng.cur</th>"
-                    u"<th>alt.old</th><th>alt.new</th><th>alt.cur</th>"
-                    u"<th>elv.old</th><th>elv.new</th><th>elv.cur</th>"
+                    u"<th>alt.old</th><th>alt.2nd</th><th>alt.new</th><th>alt.cur</th>"
+                    u"<th>elv.old</th><th>elv.2nd</th><th>elv.new</th><th>elv.cur</th>"
                     u"<th>gnd.factor</th>"
                     u"<th>onGnd.old</th><th>onGnd.new</th><th>onGnd.cur</th>"
                     u"<th>CG</th>"
@@ -320,6 +320,7 @@ namespace BlackMisc
             {
                 const CAircraftSituation situationOld = log.oldestInterpolationSituation();
                 const CAircraftSituation situationNew = log.newestInterpolationSituation();
+                const CAircraftSituation situation2nd = log.secondInterpolationSituation();
                 const bool changedNewPosition = (newPosTs != situationNew.getMSecsSinceEpoch());
                 const bool changedParts = (lastParts != log.parts);
                 newPosTs = situationNew.getMSecsSinceEpoch();
@@ -341,7 +342,7 @@ namespace BlackMisc
                     u"<td class=\"new\">" % situationNew.getTimestampAndOffset(true) % u"</td>" %
                     u"<td class=\"cur\">" % log.situationCurrent.getTimestampAndOffset(true) % u"</td>" %
 
-                    u"<td>" % msSinceEpochToTime(log.tsInterpolated) % u"</td>" %
+                    u"<td>" % msSinceEpochToTime(log.tsInterpolated)  % u"</td>" %
                     u"<td>" % QString::number(log.deltaSampleTimesMs) % u"ms</td>" %
                     u"<td>" % QString::number(log.simTimeFraction) % u"</td>" %
 
@@ -356,10 +357,12 @@ namespace BlackMisc
 
                     // tableRows +=
                     u"<td class=\"old\">" % situationOld.getAltitude().valueRoundedWithUnit(ft, 1) % u"</td>" %
+                    u"<td class=\"old\">" % situation2nd.getAltitude().valueRoundedWithUnit(ft, 1) % u"</td>" %
                     u"<td class=\"new\">" % situationNew.getAltitude().valueRoundedWithUnit(ft, 1) % u"</td>" %
                     u"<td class=\"cur\">" % log.situationCurrent.getAltitude().valueRoundedWithUnit(ft, 1) % u"</td>" %
 
                     u"<td class=\"old\">" % situationOld.getGroundElevation().valueRoundedWithUnit(ft, 1) % u" " % situationOld.getGroundElevationInfoAsString() % u"</td>" %
+                    u"<td class=\"old\">" % situation2nd.getGroundElevation().valueRoundedWithUnit(ft, 1) % u" " % situation2nd.getGroundElevationInfoAsString() % u"</td>" %
                     u"<td class=\"new\">" % situationNew.getGroundElevation().valueRoundedWithUnit(ft, 1) % u" " % situationNew.getGroundElevationInfoAsString() % u"</td>" %
                     u"<td class=\"cur\">" % log.situationCurrent.getGroundElevation().valueRoundedWithUnit(ft, 1) % u" " % log.situationCurrent.getGroundElevationInfoAsString() % u"</td>" %
 
diff --git a/src/blackmisc/simulation/interpolationlogger.h b/src/blackmisc/simulation/interpolationlogger.h
index 8485faa02..7ece81d49 100644
--- a/src/blackmisc/simulation/interpolationlogger.h
+++ b/src/blackmisc/simulation/interpolationlogger.h
@@ -17,6 +17,7 @@
 #include "blackmisc/aviation/aircraftpartslist.h"
 #include "blackmisc/aviation/aircraftsituationchange.h"
 #include "blackmisc/logcategorylist.h"
+
 #include <QObject>
 #include <QStringList>
 #include <QtGlobal>
@@ -30,13 +31,13 @@ namespace BlackMisc
         struct BLACKMISC_EXPORT SituationLog
         {
             QChar interpolator;             //!< what interpolator is used
-            qint64 tsCurrent = -1;          //!< current timestamp
-            qint64 tsInterpolated = -1;     //!< timestamp interpolated
-            double groundFactor = -1;       //!< current ground factor
-            double simTimeFraction = -1;    //!< time fraction, expected 0..1
+            qint64 tsCurrent          = -1; //!< current timestamp
+            qint64 tsInterpolated     = -1; //!< timestamp interpolated
+            double groundFactor       = -1; //!< current ground factor
+            double simTimeFraction    = -1; //!< time fraction, expected 0..1
             double deltaSampleTimesMs = -1; //!< delta time between samples (i.e. 2 situations)
-            bool useParts = false;          //!< supporting aircraft parts
-            bool vtolAircraft = false;      //!< VTOL aircraft
+            bool useParts          = false; //!< supporting aircraft parts
+            bool vtolAircraft      = false; //!< VTOL aircraft
             bool interpolantRecalc = false; //!< interpolant recalculated
             int noNetworkSituations = 0;    //!< available network situations
             int noInvalidSituations = 0;    //!< invalid situations, missing situations for timestampd
@@ -72,6 +73,14 @@ namespace BlackMisc
                 return interpolationSituations.backOrDefault();
             }
 
+            //! The second latest situation (spline)
+            const Aviation::CAircraftSituation &secondInterpolationSituation() const
+            {
+                if (interpolationSituations.size() < 2) { return Aviation::CAircraftSituation::null(); }
+                const Aviation::CAircraftSituationList::size_type i = interpolationSituations.size() - 2; // 2nd latest, latest at end
+                return interpolationSituations[i];
+            }
+
             //! To string
             QString toQString(bool withSetup,
                               bool withCurrentSituation, bool withElevation,