Is it permissible to enter into a state of ihram from an airplane? Is it a condition for the pilgrim in ihram to remain in ihram garments from the time of entering ihram until the beginning of the rituals, or can he wear his normal clothes and then put on the ihram garments when moving to Mina? Is it permissible for a pilgrim in a state of ihram who suffers from diabetic foot to wear socks?

There are three types of Hajj: Tamattu', Ifrad, and Qiran, and each is sufficient. Your father is permitted to enter into ihram with any of them. If your father enters into ihram for Hajj as Ifrad or Qiran, he should enter into ihram on the plane when aligning with the Miqat, and remain in his ihram garments until he exits the state of ihram from Hajj. If he will stay for several days before commencing Hajj and finds it difficult to remain in ihram garments, then the easier option for him is Tamattu': he would enter into ihram for 'Umrah on the plane, then exit the state of ihram, and then enter into ihram for Hajj on the eighth day. While in the state of ihram, your father must avoid the prohibitions of ihram. He is permitted to replace his ihram garment with another unstitched one. Wearing socks is permissible with the obligation of offering a fidyah (expiatory sacrifice).