AhsanAllahu elaikum If a traveller is stuck in another country because the airport is closed and does not know when they can return, can they still continue shortening the prayers indefinitely

Ustadh AbdulAziz al-Haqqan

Yes, as long as you have not decided to stay and do not know when you will be able to leave, you remain a traveller and shorten even if it lasts a long time.