Answered by Shaykh Amjad Rasheed
When is it permissible for a fasting person to omit fasting in Ramadan due to traveling?
It is permissible for one to omit fasting in Ramadan when he is traveling far, and they have measured that at 81 km or more. If he will not travel that far, it is not permissible for him to omit fasting.
It is a condition according to our imams, actually according to the vast majority (jumhur) of scholars, that the travel begin before dawn, such that he travel beyond the buildings of his village or town, before dawn. If dawn enters upon him, and he is still within buildings of his town, it is not permissible for him to omit the fast.
The Hanbalis have stated that it is permissible to omit fasting if one leaves after dawn, but it is better for him to fast, as mentioned in Al-Ansaf, and other Hanbali words.
The two imams al-Muzani (who is from our Shafi`i imams) and Ishaq ibn Rahawayh, also chose that it is permissible. This is also a weak narration [from Imam Shafi`i] in our school, that is stated by scholars other than al-Muzni, as Imam al-Nawawi mentioned in the Majmu`. Thus, whoever wishes to imitate them may do so, and Allah knows best.
[Translated by Sr. Shazia Ahmad]