It may so happen during a long journey that some travellers fall asleep in their seats and may experience wet dreams, or a traveller may board the plane having forgotten that he is in a state of janaabah, or a woman may become pure from her period or post-natal bleeding when the time for Fajr prayer begins. The plane will not reach the other country until after that time is over, and the safety regulations on board the plane absolutely forbid taking a bath in the washroom because the facilities are not suited for that. What should one do?
Praise be to Allaah.
If it is possible to do tayammum using the furnishings of the airplane, then you should do so. If that is not possible because they are free from dust, then you should pray even if you are not taahir, then as soon as you are able to purify yourself after that, then do so.
I’laam al-Musaafireen bi Ba’d Aadaab wa Ahkaam al-Safar wa ma yakhuss al-Mallaaheen al-Jawwiyyeen by Shaykh Muhammad ibn Saalih al-‘Uthaymeen, p. 13