Reference: Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-‘Ilmiyyah wal-Iftaa. – Fatwa No.5468
Fataawa Ramadhaan – Volume 1, Page 214, Fatwa No.158
Question: What is the time for breaking the fast in Ramadhaan whilst in flight?
Response: If someone is on board an aircraft during the day in Ramadhaan and he is fasting and wishes to continue his fast until sunset, then it is not permissible for him to break his fast until the sun has set [according to where the aircraft is in the sky].
And with Allaah lies all the success, and may Allaah send prayers and salutations upon our Prophet Muhammad (sal-Allaahu ‘alayhi wa sallam) and his family and his companions.