diff --git a/src/blackcore/airspacemonitor.cpp b/src/blackcore/airspacemonitor.cpp
index 4a7ad2504..0ed18ece7 100644
--- a/src/blackcore/airspacemonitor.cpp
+++ b/src/blackcore/airspacemonitor.cpp
@@ -663,10 +663,8 @@ namespace BlackCore
         // ES sends FsInn packets for callsigns such as ACCGER1, which are hard to distinguish
         // 1) checking if they are already in the list checks again ATC position which is safe
         // 2) the ATC alike callsign check is guessing
-
         Q_ASSERT_X(CThreadUtils::isCurrentThreadObjectThread(this), Q_FUNC_INFO, "not in main thread");
-        BLACK_VERIFY_X(callsign.isValid(), Q_FUNC_INFO, "invalid callsign");
-        if (!callsign.isValid()) { return; }
+        if (!callsign.isValid()) { return; } // aircraft OBS, other invalid callsigns
         if (!this->isConnectedAndNotShuttingDown()) { return; }
 
         const bool isAircraft = this->isAircraftInRange(callsign);
@@ -685,9 +683,16 @@ namespace BlackCore
 
         if (isAircraft)
         {
+            if (callsign.isCopilotCallsign())
+            {
+                this->copilotDetected();
+                return;
+            }
+
             CStatusMessageList reverseLookupMessages;
             CStatusMessageList *pReverseLookupMessages = this->isReverseLookupMessagesEnabled() ? &reverseLookupMessages : nullptr;
-            CMatchingUtils::addLogDetailsToList(pReverseLookupMessages, callsign, QString("FsInn data from network: aircraft '%1', airline '%2', model '%3', combined '%4'").
+            CMatchingUtils::addLogDetailsToList(pReverseLookupMessages, callsign,
+                                                QStringLiteral("FsInn data from network: aircraft '%1', airline '%2', model '%3', combined '%4'").
                                                 arg(aircraftIcaoDesignator, airlineIcaoDesignator, modelString, combinedAircraftType));
 
             this->addOrUpdateAircraftInRange(callsign, aircraftIcaoDesignator, airlineIcaoDesignator, "", modelString, CAircraftModel::TypeFSInnData, pReverseLookupMessages);
@@ -696,13 +701,19 @@ namespace BlackCore
         }
     }
 
-    void CAirspaceMonitor::onIcaoCodesReceived(const BlackMisc::Aviation::CCallsign &callsign, const QString &aircraftIcaoDesignator, const QString &airlineIcaoDesignator, const QString &livery)
+    void CAirspaceMonitor::onIcaoCodesReceived(const CCallsign &callsign, const QString &aircraftIcaoDesignator, const QString &airlineIcaoDesignator, const QString &livery)
     {
         Q_ASSERT_X(CThreadUtils::isCurrentThreadObjectThread(this), Q_FUNC_INFO, "not in main thread");
+        if (callsign.isCopilotCallsign())
+        {
+            // We already know that plane by its normall callsign
+            this->copilotDetected();
+            return;
+        }
+
         BLACK_VERIFY_X(callsign.isValid(), Q_FUNC_INFO, "invalid callsign");
         if (!callsign.isValid()) { return; }
         if (!this->isConnectedAndNotShuttingDown()) { return; }
-
         CStatusMessageList reverseLookupMessages;
         CStatusMessageList *pReverseLookupMessages = this->isReverseLookupMessagesEnabled() ? &reverseLookupMessages : nullptr;
         CMatchingUtils::addLogDetailsToList(pReverseLookupMessages, callsign, QString("Data from network: aircraft '%1', airline '%2', livery '%3'").
@@ -832,6 +843,11 @@ namespace BlackCore
         return c;
     }
 
+    void CAirspaceMonitor::copilotDetected()
+    {
+        // for future usage
+    }
+
     void CAirspaceMonitor::recallFsInnPacket(const CCallsign &callsign)
     {
         if (!m_tempFsInnPackets.contains(callsign)) { return; }
diff --git a/src/blackcore/airspacemonitor.h b/src/blackcore/airspacemonitor.h
index 0a6fa78f6..74c9b2446 100644
--- a/src/blackcore/airspacemonitor.h
+++ b/src/blackcore/airspacemonitor.h
@@ -251,6 +251,9 @@ namespace BlackCore
         //! Update booked station by callsign
         int updateBookedStation(const BlackMisc::Aviation::CCallsign &callsign, const BlackMisc::CPropertyIndexVariantMap &vm, bool skipEqualValues = true, bool sendSignal = true);
 
+        //! Co-pilot detected
+        void copilotDetected();
+
         //! Call CAirspaceMonitor::onCustomFSInnPacketReceived with stored packet
         void recallFsInnPacket(const BlackMisc::Aviation::CCallsign &callsign);
 
diff --git a/src/blackmisc/aviation/callsign.cpp b/src/blackmisc/aviation/callsign.cpp
index a86f206bf..aefffc8c5 100644
--- a/src/blackmisc/aviation/callsign.cpp
+++ b/src/blackmisc/aviation/callsign.cpp
@@ -87,6 +87,11 @@ namespace BlackMisc
             return m_callsign.endsWith("SUP");
         }
 
+        bool CCallsign::isCopilotCallsign() const
+        {
+            return (this->getTypeHint() == Aircraft) && this->isObserverCallsign();
+        }
+
         QString CCallsign::getIcaoCode() const
         {
             if (this->isAtcCallsign())
@@ -96,7 +101,7 @@ namespace BlackMisc
                     return m_callsign.left(4).toUpper();
                 }
             }
-            return "";
+            return QStringLiteral("");
         }
 
         bool CCallsign::isAtcAlikeCallsign() const
@@ -108,7 +113,6 @@ namespace BlackMisc
 
         bool CCallsign::isObserverCallsign() const
         {
-            if (this->getTypeHint() == Aircraft) { return false; }
             return m_callsignAsSet.endsWith("_OBS", Qt::CaseInsensitive);
         }
 
diff --git a/src/blackmisc/aviation/callsign.h b/src/blackmisc/aviation/callsign.h
index 97d52fd83..ac784eb28 100644
--- a/src/blackmisc/aviation/callsign.h
+++ b/src/blackmisc/aviation/callsign.h
@@ -84,6 +84,9 @@ namespace BlackMisc
             //! Supervisor?
             bool isSupervisorCallsign() const;
 
+            //! Pilot OBS callsign, normally a co-pilot
+            bool isCopilotCallsign() const;
+
             //! Get callsign (normalized)
             const QString &asString() const { return m_callsign; }