diff --git a/src/blackgui/components/loginadvcomponent.cpp b/src/blackgui/components/loginadvcomponent.cpp
index a0dda8302..9196b06aa 100644
--- a/src/blackgui/components/loginadvcomponent.cpp
+++ b/src/blackgui/components/loginadvcomponent.cpp
@@ -82,7 +82,7 @@ namespace BlackGui
 
             connect(ui->pb_Cancel,  &QPushButton::clicked, this, &CLoginAdvComponent::loginCancelled,          Qt::QueuedConnection);
             connect(ui->pb_Connect, &QPushButton::clicked, this, &CLoginAdvComponent::toggleNetworkConnection, Qt::QueuedConnection);
-            connect(ui->comp_NetworkDetails, &CNetworkDetailsComponent::overridePilot, this, &CLoginAdvComponent::overrideCredentialsToPilot,      Qt::QueuedConnection);
+            connect(ui->comp_NetworkDetails, &CNetworkDetailsComponent::overridePilot,          this, &CLoginAdvComponent::overrideCredentialsToPilot,      Qt::QueuedConnection);
             connect(ui->comp_NetworkDetails, &CNetworkDetailsComponent::requestNetworkSettings, this, &CLoginAdvComponent::requestNetworkSettings, Qt::QueuedConnection);
 
             // overlay
@@ -104,6 +104,7 @@ namespace BlackGui
             // Stored data
             this->loadRememberedUserData();
 
+            // signals
             if (sGui && sGui->getIContextSimulator())
             {
                 connect(sGui->getIContextSimulator(), &IContextSimulator::vitalityLost, this, &CLoginAdvComponent::autoLogoffDetection, Qt::QueuedConnection);
@@ -155,7 +156,8 @@ namespace BlackGui
                 const CStatusMessageList pilotMsgs = ui->form_Pilot->validate();
                 if (pilotMsgs.isFailure())
                 {
-                    this->showOverlayHTMLMessage(CStatusMessage(this).validationWarning(u"Invalid pilot data, login not possible"), OverlayMessageMs);
+                    // this->showOverlayHTMLMessage(CStatusMessage(this).validationWarning(u"Invalid pilot data, login not possible"), OverlayMessageMs);
+                    this->showOverlayMessagesOrHTMLMessage(pilotMsgs, false, OverlayMessageMs);
                     return;
                 }
 
@@ -168,13 +170,13 @@ namespace BlackGui
                 const INetwork::LoginMode mode = ui->comp_NetworkDetails->getLoginMode();
                 switch (mode)
                 {
-                case INetwork::LoginStealth: CLogMessage(this).info(u"login in stealth mode"); break;
+                case INetwork::LoginStealth:    CLogMessage(this).info(u"login in stealth mode"); break;
                 case INetwork::LoginAsObserver: CLogMessage(this).info(u"login in observer mode"); break;
                 default: break; // INetwork::LoginNormal
                 }
 
                 // Server
-                currentServer = this->getCurrentServer();
+                currentServer    = this->getCurrentServer();
                 const CUser user = this->getUserFromPilotGuiValues();
                 currentServer.setUser(user);
 
@@ -191,18 +193,38 @@ namespace BlackGui
                     currentServer.setVoiceSetup(voice);
                 }
 
+                // update for own aircraft context
                 sGui->getIContextOwnAircraft()->updateOwnAircraftPilot(currentServer.getUser());
 
                 // set own aircraft from all values
                 ownAircraft = sGui->getIContextOwnAircraft()->getOwnAircraft();
 
+                // check the copilot stuff
+                CCallsign partnerCs;
+                if (ui->comp_NetworkDetails->hasPartnerCallsign())
+                {
+                    partnerCs = ui->comp_NetworkDetails->getPartnerCallsign();
+                    if (partnerCs == ownAircraft.getCallsign())
+                    {
+                        this->showOverlayHTMLMessage("Your callsign and the pilot/copilot callsign must be NOT the same", OverlayMessageMs);
+                        return;
+                    }
+
+                    const bool ok = (partnerCs.asString().startsWith(ownAircraft.getCallsignAsString(), Qt::CaseInsensitive) || ownAircraft.getCallsignAsString().startsWith(partnerCs.asString(), Qt::CaseInsensitive));
+                    if (!ok)
+                    {
+                        this->showOverlayHTMLMessage("Callsign and the pilot/copilot callsign appear not to be synchronized", OverlayMessageMs);
+                        return;
+                    }
+                }
+
                 // Login
-                if (sGui->getIContextAudio())
+                if (sGui && sGui->getIContextAudio())
                 {
                     sGui->getIContextAudio()->setVoiceSetup(currentServer.getVoiceSetup());
                 }
 
-                msg = sGui->getIContextNetwork()->connectToNetwork(currentServer, values.ownLiverySend, values.useLivery, values.ownAircraftModelStringSend, values.useModelString, mode);
+                msg = sGui->getIContextNetwork()->connectToNetwork(currentServer, values.ownLiverySend, values.useLivery, values.ownAircraftModelStringSend, values.useModelString, partnerCs, mode);
                 if (msg.isSuccess())
                 {
                     Q_ASSERT_X(currentServer.isValidForLogin(), Q_FUNC_INFO, "invalid server");
diff --git a/src/blackgui/components/logincomponent.cpp b/src/blackgui/components/logincomponent.cpp
index 483c3cf97..20b2028c1 100644
--- a/src/blackgui/components/logincomponent.cpp
+++ b/src/blackgui/components/logincomponent.cpp
@@ -327,7 +327,7 @@ namespace BlackGui
                     sGui->getIContextAudio()->setVoiceSetup(currentServer.getVoiceSetup());
                 }
 
-                msg = sGui->getIContextNetwork()->connectToNetwork(currentServer, {}, true, {}, true, mode);
+                msg = sGui->getIContextNetwork()->connectToNetwork(currentServer, {}, true, {}, true, {}, mode);
                 if (msg.isSuccess())
                 {
                     Q_ASSERT_X(currentServer.isValidForLogin(), Q_FUNC_INFO, "invalid server");
diff --git a/src/blackgui/components/networkdetailscomponent.cpp b/src/blackgui/components/networkdetailscomponent.cpp
index 2c4a83486..43fa55c5f 100644
--- a/src/blackgui/components/networkdetailscomponent.cpp
+++ b/src/blackgui/components/networkdetailscomponent.cpp
@@ -17,6 +17,7 @@
 
 using namespace BlackMisc::Network;
 using namespace BlackMisc::Audio;
+using namespace BlackMisc::Aviation;
 using namespace BlackCore;
 using namespace BlackCore::Data;
 
@@ -59,10 +60,10 @@ namespace BlackGui
 
             constexpr int MaxLength = 10;
             constexpr int MinLength = 0;
-            CUpperCaseValidator *ucv = new CUpperCaseValidator(MinLength, MaxLength, ui->le_Copilot);
+            CUpperCaseValidator *ucv = new CUpperCaseValidator(MinLength, MaxLength, ui->le_PartnerCallsign);
             ucv->setAllowedCharacters09AZ();
-            ui->le_Copilot->setMaxLength(MaxLength);
-            ui->le_Copilot->setValidator(ucv);
+            ui->le_PartnerCallsign->setMaxLength(MaxLength);
+            ui->le_PartnerCallsign->setValidator(ucv);
 
             const int tab = m_networkSetup.wasLastUsedWithOtherServer() ? LoginOthers : LoginVATSIM;
             ui->tw_Network->setCurrentIndex(tab);
@@ -243,6 +244,17 @@ namespace BlackGui
             return this->isVatsimServerSelected() ? this->getCurrentVatsimServer() : this->getCurrentOtherServer();
         }
 
+        bool CNetworkDetailsComponent::hasPartnerCallsign() const
+        {
+            return !ui->le_PartnerCallsign->text().isEmpty();
+        }
+
+        CCallsign CNetworkDetailsComponent::getPartnerCallsign() const
+        {
+            if (ui->le_PartnerCallsign->text().isEmpty()) { return {}; }
+            return CCallsign(ui->le_PartnerCallsign->text(), CCallsign::Aircraft);
+        }
+
         void CNetworkDetailsComponent::reloadOtherServersSetup()
         {
             const CServerList otherServers(m_networkSetup.getOtherServersPlusPredefinedServers());
diff --git a/src/blackgui/components/networkdetailscomponent.h b/src/blackgui/components/networkdetailscomponent.h
index 2fac1bc06..762a9beb4 100644
--- a/src/blackgui/components/networkdetailscomponent.h
+++ b/src/blackgui/components/networkdetailscomponent.h
@@ -100,6 +100,12 @@ namespace BlackGui
             //! Current server based on selected tab
             BlackMisc::Network::CServer getCurrentServer() const;
 
+            //! Pilot or Co-pilot callsign?
+            bool hasPartnerCallsign() const;
+
+            //! Pilot or Co-pilot callsign
+            BlackMisc::Aviation::CCallsign getPartnerCallsign() const;
+
         signals:
             //! Override the pilot
             void overridePilot(const BlackMisc::Network::CUser &user);
diff --git a/src/blackgui/components/networkdetailscomponent.ui b/src/blackgui/components/networkdetailscomponent.ui
index 5a57fbc8e..ca6e8edaf 100644
--- a/src/blackgui/components/networkdetailscomponent.ui
+++ b/src/blackgui/components/networkdetailscomponent.ui
@@ -250,9 +250,9 @@
            <number>0</number>
           </property>
           <item row="1" column="1">
-           <widget class="QLineEdit" name="le_Copilot">
+           <widget class="QLineEdit" name="le_PartnerCallsign">
             <property name="placeholderText">
-             <string>partner callsign</string>
+             <string>partner callsign (pilot/co-pilot)</string>
             </property>
            </widget>
           </item>
@@ -276,7 +276,7 @@
           <item row="1" column="0">
            <widget class="QLabel" name="lbl_Copilot">
             <property name="text">
-             <string>Co/Pilot callsign</string>
+             <string>Partner callsign</string>
             </property>
            </widget>
           </item>
@@ -418,7 +418,7 @@
   <tabstop>comp_VatsimServers</tabstop>
   <tabstop>pb_DetailsVatsim</tabstop>
   <tabstop>pb_OverrideCredentialsVatsim</tabstop>
-  <tabstop>le_Copilot</tabstop>
+  <tabstop>le_PartnerCallsign</tabstop>
   <tabstop>comp_OtherServers</tabstop>
   <tabstop>pb_RefreshOtherServers</tabstop>
   <tabstop>pb_OtherServersGotoSettings</tabstop>