Is it permissible to board a plane that takes off on Friday and lands on Motza'ei Shabbat or Sunday morning? Consider, for example, the case of a Jew who wishes to fly from Los Angeles to Hong Kong, and he can take a flight that takes off from Los Angeles on Friday afternoon and lands in Hong Kong after Shabbat. Assuming he performs no Melacha on the airplane, would this be permissible?
According to Halacha it is unequivocally forbidden to fly on Shabbat, for many different reasons. For one thing, Halacha forbids traveling beyond two thousand Amot (cubits) outside one's city on Shabbat. And although this prohibition (which is known as "Techum Shabbat") generally does not apply higher than ten Tefachim (handbreadths) in the air, in this case it likely will apply given the size of the aircraft. Furthermore, one would be unable to use the restrooms on the plane, as the light switches on or off whenever one opens or closes the doors. In addition, planes are equipped with all kinds of electronic sensors, such that one's movement in the aircraft invariably activates some electronic device. It should also be noted that any food served during a flight has been heated on the plane, and therefore one who eats food on a flight during Shabbat will be deriving benefit from forbidden activity, which Halacha prohibits. Some authorities further claim that one's presence on the aircraft adds to the weight supported by the engine, and thus causes more fuel to be burned. Finally, it is clearly impossible to properly fulfill the obligation of Oneg Shabbat enjoying oneself on Shabbat while flying on an airplane.
For all these reasons, as well as many others, Halacha categorically forbids flying on an airplane on Shabbat, even if the plane takes off before Shabbat and lands after Shabbat.
