Q: Assuming that during prayer in an airoplane, one can observe stillness, standing, performing rukū‘ and prostration in a proper way and other requirements but does not know qiblah direction, is it allowed for him to pray there and what is his duty?
A: If he can find qiblah direction for sure later and say his prayer during its time, he should wait. However, if prayer is going to become qaḍā’ (i.e. he will miss the prayer during its time), he should say the prayer facing the direction which is that of qiblah most probably. If he has no way to find out qiblah and all directions enjoy the same probability to be qiblah, he should say the prayer towards four directions and if he does not have enough time, he should say the prayer towards the directions which time allows him to.