There is almost no problem in changing clothes to the pilgrims who depart from Medina; Because they had to stop at Dzul Hulaifah on the way to Makkah. Problems arise when pilgrims go directly to Makkah. Where do they change the clothes?
I have Indonesia for example because i am Indonesian. Generally Indonesian’s pilgrims are divided into two groups. Some change their clothes in the plane and others wait until depart in Jeddah, because they thought it is impossible to do it in the plane. Is it?
If you understand how it works, in sya’ Allah no difficulty to do it in Yalamlam as the prophet command. He ordered every moslem to change their clothes in specific places as narrated by Abdullah bin Al-Abbas, ان النبي وقت لاهل المدينة ذا الحليفة و لاهل اشام الجحفة و لاهل نجد قرن المنازل و لاهل يمن يلملم. و قال: هن لهن و لمن اتي عليهن من غير اهلحن ممن اراد الحج و الامرة و من كان دون ذلك فمن حيث انشا حتي اهل مكة من مكة”The Prophet has established Dhul Hulaifah as the miqot (place to wear ihram clothes) of Medina’s people; Juhfah as a miqot of Sham’s (Syiria, Lebanon, Palestine, Israel, and Jordan) people; Qarnul Manazil as the miqot of the Nejd’s people; And Yalamlam as the miqot of the Yemen’s people. And he said: these places as miqot for its inhabitants and for people from other countries who come there who want to perform hajj and umra. Whosoever abides in the miqots, then he change the cloth from his residence, until the people of Makkah (change the clothes from Mecca). “
For Indonesia’s Pilgrim
The important thing we (Indonesian) forget that the inhabitants of the Nusantara (now Indonesia) in particular and Southeast Asia generally traditionally go to Mecca through the sea. From the Indian Ocean, India, Yemen, the Red Sea, and Jeddah. This means that the pilgrims from Indonesia will pass through Yalamlam which is about half an hour before Jeddah (by plane).
In the past, when pilgrims from Indonesia still used ships to reach Jeddah; they will stop for a moment in Yalamlam to give an opportunity for changing cloth. Dr. M. Shaleh Putuhena in Historiografi Haji Indonesia page 136 writes: “… After several days of sailing, they arrived in the city of Alfiah, a city partly Muslim and part Hindu. In this city Abdullah had to change ships. After waiting for six days, Abdullah and other Hajj pilgrims continued their journey on the ship of Haji Atia Rahman who had arrived from Kalkatah. On the way to Jeddah, the ship visited Kalikut, Mokha, and Hudaiah. The day before arriving in Jeddah, the ship, halting its speed, “wriggling” in Yalamlam for the pilgrims had the opportunity to wear ihram clothes. As you know, Yalamlam is a place to change clothes for Nusantara’s pilgrims.”
 Shahih. HR. Al-Bukhari (no.1254) and Muslim (1182). Ustadz Yazid bin Abdul Qadir Jawas and Ustadz Mubarok bin Mahfudh Bamualim, Lc in Panduan Manasik Haji & Umrah, p. 45.