If I understand the question correctly, you are attempting to overwrite the Page Name (defaults to URL) in Google Analytics with a custom name. The best way to do this is to create a Set Data Values extension, setting the desired name in a variable ("/passenger_details" from your question), not in the Tealium pathname or URL. You can either use an existing variable, or create a new one just for this purpose. Then, like you have done, set a condition where this variable is populated on the desired page.
Once this Extension is created, go into the Google Analytics tag and edit the Mapped Data Sources. Select your new variable under the Data Sources dropdown, and click on the Select Destination button. Select Page Name (Override Default) and click on Save. Finally publish these changes and you should start to see the desired name show in the "utmp" query string parameter.
Please let us know if you need additional information on this process, or require additional assistance.