diff --git a/src/blackgui/components/logincomponent.cpp b/src/blackgui/components/logincomponent.cpp
index c07eb664c..c43af1265 100644
--- a/src/blackgui/components/logincomponent.cpp
+++ b/src/blackgui/components/logincomponent.cpp
@@ -122,8 +122,12 @@ namespace BlackGui
             // So I use no ranges in the CUpperCaseValidators, as this disables the signals for invalid values
 
             // own aircraft
-            ui->le_Callsign->setMaxLength(LogoffIntervalSeconds);
-            ui->le_Callsign->setValidator(new CUpperCaseValidator(this));
+            constexpr int MaxLength = 10;
+            constexpr int MinLength = 0;
+            CUpperCaseValidator *ucv = new CUpperCaseValidator(MinLength, MaxLength, ui->le_Callsign);
+            // ucv->setAllowedCharacters09AZ();
+            ui->le_Callsign->setMaxLength(MaxLength);
+            ui->le_Callsign->setValidator(ucv);
             connect(ui->le_Callsign, &QLineEdit::editingFinished, this, &CLoginComponent::validateAircraftValues);
 
             ui->le_AircraftCombinedType->setMaxLength(3);
diff --git a/src/blackgui/uppercasevalidator.cpp b/src/blackgui/uppercasevalidator.cpp
index 91ab28e79..3b8ad2db5 100644
--- a/src/blackgui/uppercasevalidator.cpp
+++ b/src/blackgui/uppercasevalidator.cpp
@@ -30,11 +30,17 @@ namespace BlackGui
         if (minLength < 1) { m_optionalValue = true; };
     }
 
+    void CUpperCaseValidator::setAllowedCharacters09AZ()
+    {
+        static const QString chars("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ");
+        this->setAllowedCharacters(chars);
+    }
+
     QValidator::State CUpperCaseValidator::validate(QString &input, int &pos) const
     {
         Q_UNUSED(input);
         Q_UNUSED(pos);
-        fixup(input);
+        this->fixup(input);
 
         if (m_optionalValue && input.isEmpty()) { return Acceptable; }
         if (input.length() > m_maxLength) { return Invalid; }
diff --git a/src/blackgui/uppercasevalidator.h b/src/blackgui/uppercasevalidator.h
index 83c849ff6..13cd84dcb 100644
--- a/src/blackgui/uppercasevalidator.h
+++ b/src/blackgui/uppercasevalidator.h
@@ -38,6 +38,9 @@ namespace BlackGui
         //! Allowed characters
         void setAllowedCharacters(const QString &chars) { m_allowedCharacters = chars.toUpper(); }
 
+        //! Set the allowed characters as 0-9 and A-Z
+        void setAllowedCharacters09AZ();
+
         //! \copydoc QValidator::validate
         virtual State validate(QString &input, int &pos) const override;