Q: What time should a pilgrim traveling by plane enter into the state of Ihram (ritual state for Hajj and `Umrah)?

A: Like pilgrims traveling on land, others traveling by air or sea are required to enter into the state of Ihram once they come in line with the prescribed Miqat (site for entering the ritual state for Hajj and `Umrah). They are allowed to enter into the state of Ihram a short time before reaching the Miqat if they fear the speed of the plane or ship may make them have no time to enter into Ihram.

[Fataawa Shaykh Ibn Baaz - Alifta.net]