Check in through the app first. Check-in only opens 24 hours before the flight for non Cathay Pacific members, while for members it is 48 hours. Depending on your flights and documents, you cannot get boarding passes for some flights, for example when you use BNO passport or traveling to Taiwan or Mainland China.If a boarding pass can indeed be issued, the app will provide you 3 options - download the boarding pass to the app, send it to you via SMS or via email. You can do all of them. Then, you can access the boarding pass inside the app without timeout.The email and SMS option is actually just send you an link to open a webpage of your boarding pass, so as long as you keep the browser tab open it will always be there.