Answered by Sidi Mostafa Azzam
In the article on shortening prayers during Hajj, you mentioned that Arafah is not far enough from Makkah to shorten prayers in our school. You also mentioned that, in order to avoid having to pray jumu’ah, one can leave Makkah Friday night, before fajr. This implies that the travel that permits one to miss jumu’ah is shorter than the travel that permits one to combine and shorten prayers. How far is the travel that permits one to miss jumu’ah?
As you have observed, the travel that allows missing the Friday (Jumu`ah) prayer is shorter than the travel that allows shortening and combining. For a journey to allow shortening and combining, it must be a long journey (approximately 81 km), whereas even a short journey allows missing the Friday prayer, provided that it is far enough outside of town that one would not hear the azan if it was made from the edge of town and provided that one had left town before dawn (Hashiyat al-Jamal, 2:4-12 (Dar Ihya’ al-Turath al-`Arabi). See Reliance f18.2-3.