The Miqat boundaries (designated entry points for الإحرام) apply whether you travel by land or air — passing them without being in الإحرام when you intend الحج or العمرة is not permitted. Since modern flights are fast, preparation is key. The practical approach is to perform الغسل (ritual bathing) and grooming at home or the departure airport, then change into your الإحرام garments either before boarding or in the airplane lavatory before the Miqat is reached.
Most airlines operating الحج and العمرة flights announce when the plane is approaching the Miqat boundary. If your airline does not make this announcement, use a GPS-based Miqat alert app (الإحرامOS includes this feature) or research your flight path to estimate the timing. Common Miqat points for air travelers include: Dhat Irq for those coming from the east, Yalamlam for those from the south, and Al-Juhfah for those from the north and west.
Once you are in your الإحرام garments and approaching the Miqat, make your intention (niyyah) in your heart — specifying whether you are performing الحج, العمرة, or both — and begin reciting the التلبية: 'Labbayk Allahumma labbayk...' If you realize you have passed the Miqat without entering الإحرام, the majority of scholars say you must either return to the Miqat (if possible) or pay a فدية (sacrifice a sheep in مكة). To avoid this situation, it is safest to enter الإحرام well before the estimated Miqat crossing.