FASTING BY A TRAVELLER.

1. A traveler for whom it is obligatory to shorten a four rak’ats prayers to two rak’ats,  should not fast. However, a traveler who offers full prayers, like, a person who is a traveler by profession or who goes on a journey for a haraam purpose, should fast while traveling.
2. If a person does not know that the fast of a traveler is invalid and observes fast while journeying, and learns about the rule during the day, his fast becomes void, but if he does not learn about the rule till maghrib, his fast is valid.
3. If a person forgets that he is a traveler or forgets that the fast of a traveler is void, and observes fast while journeying, his fast is invalid.
4. If a fasting person travels after zuhr, he should, as a precaution, complete his fast.
5. If a fasting person travels before zuhr and had an intention from the previous night to do so, he cannot fast on that day. As a precaution, he cannot fast on that day even if he had no intention to travel from the previous night. In both the cases, he cannot break the fast till he has reached the limit of tarakkhus. If he does, he will be liable to give kaffarah. Note: Masaels relating to the limit of tarakkhus can be obtained from your Resident Aalim or refer to Taudhihul Masael book in the section of Prayers of a traveler.)
6. If a traveler reaches his hometown or a place where he intends to stay for ten days or more before zuhr, and if he has not committed an act which invalidates a fast, he should fast on that day. But if he reaches after zuhr, he cannot fast on that day.

CONTEMPORARY RULINGS.
Q. What about one whose duty is to fast while traveling. After dawn has appeared in his city, he
travels by air with the intention to fast. He arrives in another city where the dawn has not yet
emerged. Is he permitted to eat, drink, etc.?
A. Apparently, it is permissible.

Q. What about one who travels from his city in the month of Ramadhan after noon and arrives in
a city where the sun has not begun its descent. Is it obligatory for him to abstain (from things
that break the fast) and complete his fast?
A. That is a better precaution.

Q. If a fasting person in the month of Ramadhan travels by air in a westenrly direction after maghrib --
without breaking (iftar) his fast in his city -- and arrives at a place where the sun has not yet set, is
it obligatory for him to abstain from things (that break the fast) until maghrib?
A. Apparently, it is not obligatory although it is a better precaution.

Q. What about one whose duty is to fast while traveling. If he travels from his city, in which the
crescent of Ramadhan has been seen, to a city where the crescent has not yet been seen
because of a variation in their horizon?
A. He is not obliged to fast on that day.

Q. What if he observes the Eid in a city in which the crescent of Shawwal has been seen, and then
travels to a city where the crescent has not been seen due to a variation in their horizon?
A. It is a better precaution for him to abstain (from things that break the fast) for the rest of the day
and, also, to observe its qadha.

NOTE: RELEVANT DETAILS OF THINGS OR ACTS WHICH ARE MAKROOH/MUSTAHAB FOR A PERSON OBSERVING FAST, QADHA FASTS, KAFFARA, ETC. CAN BE OBTAINED
FROM YOUR RESIDENT AALIM OR REFER TO THE ISLAMIC LAWS BOOK.