How can prayer times be calculated on an airplane during a flight from Bahrain to Sydney and vice versa, taking into account the time difference and the duration of the journey?

The determining factor for the commencement of prayer times is the location where a person is present. If day and night are distinguishable in that location, then one prays according to the timings there. However, if night or day is continuous, then prayer times must be estimated based on the closest land where times are distinguishable, as the Prophet, peace and blessings be upon him, said regarding the Dajjal: "Estimate its measure accordingly." Prayer times on an airplane can be determined by knowing the advent of dawn for Fajr prayer, and by exercising diligence and seeking assistance from the airplane crew to ascertain the entry of Dhuhr time for Dhuhr and Asr prayers, and by sunset for Maghrib and Isha prayers. Combining prayers is permissible in this situation.