All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, is His slave and Messenger.
Do not combine the Thuhr and ‘Asr prayers before starting your journey, because you are still a resident. The basic principle in case of residence is to perform each prayer on its due time, unless there is a Sharee‘ah-approved excuse that permits combining the prayers. The excuses that permit combining the prayers for a resident are rain and illness. However, some scholars held that it is allowable for a resident to combine the prayers, even in the absence of illness and rain, when something happens that makes it hard to perform each prayer on its due time. This is evidenced by the Hadeeth narrated on the authority of Ibn ‘Abbaas as he said: “The Messenger of Allah combined the Thuhr and ‘Asr prayers and combined the Maghrib and ‘Ishaa’ prayers in Madeenah, without being in a state of fear, nor due to rain.” Ibn ‘Abbaas was asked: “What did he intend by that action?” He replied: “He did not want to inconvenience his Ummah (Islamic community).” [Muslim, Ahmad, Abu Daawood, and At-Tirmithi]
The author of Tuhfat Al-Ahwathi said: “It means that he did so to spare his nation any hardship or burden. He, sallallaahu ‘alayhi wa sallam, intended to make things easier for them.” [End of Quote]
Ibn Hajar said in Fat-h Al-Baari: “A group of scholars held that the apparent indication (i.e. literal meaning) of this Hadeeth should be applied. Accordingly, they maintained that it is permissible for a resident to combine the prayers for a need without restrictions provided that he does not make it a habit. The scholars who held this opinion included Ibn Seereen, Rabee‘ah, Ash-hab, Ibn Al-Munthir, and Al-Qaffaal Al-Kabeer. Al-Khattaabi also reported this view from a group of Hadeeth scholars of the early generations.” [End of Quote]
In conclusion, you should not combine the Thuhr and ‘Asr prayers before going to the airport; this is the basic principle in this regard. However, if performing each prayer on its due time entails hardship, then we hope that you are permitted to take advantage of the concession of combining the prayers in this case according to the opinion of some scholars, as mentioned above.
It should be noted that it is not permissible to shorten the prayers in this case, because shortening the prayers is exclusively permitted during travel.
For more benefit, please refer to Fatwa 99571.
Allah knows best.