Answer
(Fatwa: 1069/1070/M=1432)
Salah is offered facing Qiblah direction though one is travelling by train or plane. It is a condition in salah to turn towards Qiblah direction. If one has no knowledge about Qiblah and does not carry compass with him, then one should guess Qiblah direction during daytime by watching the sun and if it is night or it is daytime but the sun is invisible then one should imply other sings and indications with full deliberation. Then, he should perform salah facing the direction to which his heart tends.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband