Praise be to Allah.
The scholars are agreed that covering the head is haraam for a man in ihraam. This is indicated by the words of the Prophet (peace and blessings of Allah be upon him) concerning a man who died in ‘Arafah when he was in ihraam: “Wash him with water and lotus leaves, and shroud him in two cloths, and do not put any perfume on him or cover his head, for Allah will resurrect him on the Day of Resurrection reciting the Talbiyah.” Narrated by al-Bukhaari, 1267; Muslim, 1206.
Al-Bukhaari (1542) and Muslim (1177) narrated from ‘Abd-Allah ibn ‘Umar (may Allah be pleased with him) that a man said, “O Messenger of Allah, what garments should the muhrim wear?” The Messenger of Allah (peace and blessings of Allah be upon him) said: “He should not wear a shirt, or a turban, or pants, or a burnoose or khifaaf (shoes).” The burnoose is a garment worn by the people of the Maghreb (North Africa) which has a hood attached.
The muhrim’s covering his head is of various kinds:
1 – Covering it with something that stays on the head, such as a hat or turban and the like. This is haraam. The evidence for it being haraam is the two hadeeth quoted above.
2 – Covering his head with something that does not stay on it, such as an umbrella, tent, car roof etc. There is nothing wrong with this, because Umm Husayn (may Allah be pleased with her) said: “I performed Hajj with the Messenger of Allah (peace and blessings of Allah be upon him) during the Farewell Pilgrimage, and I saw him when he stoned Jamarat al-‘Aqabah and went away on his mount, accompanied by Bilaal and Usaamah. One of them was leading his mount and the other was holding his garment over the head of the Messenger of Allah (peace and blessings of Allah be upon him), shading him from the sun. Narrated by Muslim, 1298.
This indicates that it is permissible for the muhrim to shade his head with a cloth or whatever. This is our view and the view of the majority of scholars.
Shaykh Ibn ‘Uthaymeen said: this is exactly like an umbrella.
Shaykh Ibn Baaz said: There is nothing wrong with the muhrim using an umbrella to shield himself from the sun, or shading himself in a tent or under the roof of a car. Fatawa Ibn Baaz, 17/115.
3 – Carrying one’s luggage on one's head. There is nothing wrong with this because it is usually not done with the intention of covering the head. If it is done with that intention then it is haraam.
Shaykh Ibn Baaz said:
Carrying luggage is not covering the head, it is like the muhrim carrying food and the like, so long as he is not doing that as a trick (to get around the ruling), because Allah has forbidden His slaves to use trickery in order to do things that He has forbidden.
Fatawa Ibn Baaz, 17/115
And Allah knows best.