On the ground, iftar is a time printed on a timetable. On an aircraft there is no timetable that applies: you are crossing a time zone every hour or so, the city you left keeps its own sunset, and the city you are flying to keeps another. Passengers end up asking which of the two to follow, and the honest answer is neither.
The fast ends at sunset, and sunset is an event you can see. What changes on a plane is where you are when it happens, how high you are when you see it, and how fast you are moving relative to it. All three can be measured, so we measured them — and then set out the concession that makes most of this optional.
The rule: the sunset you actually see
The Quran fixes the end of the fast by the night, not by a clock: "then complete the fast until the night" (2:187). The Prophet ﷺ defined that moment by observation — when night approaches from the east, the day departs from the west and the sun has set, the fasting person breaks the fast (Sahih al-Bukhari 1954). Nothing in either text refers to a city.
Contemporary scholars who have addressed flights apply this directly. The position given in widely cited fatwas, including by Shaykh Ibn Baz, is that a passenger who is fasting breaks the fast when the sun sets as seen from the aircraft, even if the ground below or the departure city reached sunset earlier. The corollary matters just as much: if your departure city has reached Maghrib but you can still see the sun from your window, you have not.
In practice, few passengers can see the western horizon from their seat, and the in-flight map rarely shows sun altitude. The cabin crew can usually tell you whether the sun is still up, and many airlines serving Muslim-majority routes announce iftar. When you genuinely cannot tell, the fiqh default is caution: you continue until you are confident the sun has set, since a fast broken before sunset in error has to be made up.
Four routes on 15 Ramadan 2027
Ramadan 1448 runs from 8 February to 8 March 2027 on the Umm al-Qura calendar. We took its midpoint, 22 February, and four long-haul routes with realistic but illustrative departure times. For each we moved the aircraft along the great-circle path second by second and found the moment the sun's centre dropped below the horizon as seen from 11 km up. The fast is measured from Fajr at the departure city, since that is where suhoor was eaten.
The direction of travel decides almost everything. Flying east, you meet the night: London to Kuala Lumpur loses two and a half hours of fasting, and New York to Istanbul, leaving mid-morning, meets sunset over the North Atlantic at 14:33 New York time. Flying west, you run with the sun. An afternoon departure from London stays in daylight for almost the whole crossing and sees the sun set only as it descends towards New York — a fast of 17 hours 39 minutes, over five hours longer than the day it began in.
| Route | Departs | Sun sets from aircraft | Over | Fast | On the ground |
|---|---|---|---|---|---|
| London → Kuala Lumpur | 11:00 | 3 h 54 m in, 14:54 | 48.2° N, 44.3° E | 9 h 43 m | 12 h 18 m |
| New York → Istanbul | 10:00 | 4 h 33 m in, 14:33 | 54.1° N, 27.1° W | 9 h 25 m | 12 h 30 m |
| Dubai → Los Angeles | 09:00 | 8 h 13 m in, 17:13 | 83.5° N, 1.9° E | 11 h 42 m | 12 h 45 m |
| London → New York | 15:00 | 7 h 50 m in, 17:50 NY | 41.3° N, 72.7° W | 17 h 39 m | 12 h 18 m |
Why the sun sets later from 11 kilometres up
At cruising altitude the horizon is not level with your eye; it lies below it, because you are looking down over the curve of the Earth. That angle is called the dip. At 11,000 metres it is 3.36° geometrically, or about 3.08° once atmospheric refraction is allowed for — which is the figure we used. The sun therefore has to sink roughly three degrees further before it disappears from the aircraft than it does for someone standing on the ground directly beneath.
Three degrees of sun is not a trivial amount of time. For an observer who was not moving, it would delay sunset by between 12 and 26 minutes depending on latitude, because the sun descends steeply at the equator and at a shallow slant further north. On a moving aircraft the effect is larger or smaller depending on direction: eastbound, the plane flies into the dusk and the gap is under 12 minutes; westbound it is stretched — 35 minutes on the London to New York run, 47 over the Arctic.
This is the concrete reason the "ground below" rule does not work. A passenger on the London to New York flight who used the sunset of the land beneath them would have broken the fast 35 minutes before the sun had set from where they were sitting.
| Case | Delay |
|---|---|
| Stationary, equator | 12.5 min |
| Stationary, 25° N | 13.8 min |
| Stationary, 40° N | 16.4 min |
| Stationary, 51.5° N (London) | 20.4 min |
| Stationary, 60° N | 25.7 min |
| London → Kuala Lumpur (eastbound) | 11.8 min |
| New York → Istanbul (eastbound) | 11.7 min |
| London → New York (westbound) | 35.5 min |
| Dubai → Los Angeles (polar) | 47.4 min |
The polar route, where the sun comes back
Dubai to Los Angeles on a pure great circle crosses to 84.6° N, about five and a half degrees from the North Pole. In late February that is the edge of the polar night. On our track the sun set from the aircraft 8 hours 13 minutes after departure at 83.5° N — and then, 92 minutes later, rose again over the Canadian Arctic as the aircraft turned south. The sun never dropped more than five degrees below the horizon in between. For the rest of the flight it was daylight.
The fast in that case ended at the sunset you saw; that part follows from the rule. What the reappearing sun means for the hours afterwards is not something the classical texts address, and we are not aware of a settled contemporary answer. It is exactly the kind of case where asking a scholar you trust before you fly is better than improvising at 35,000 feet — and where the travel concession below is the simplest way out.
You do not have to fast at all
All of the above applies to a traveller who chooses to fast. The Quran gives the traveller the option not to: "whoever among you is ill or on a journey, then an equal number of other days" (2:184). A long-haul flight is a journey on every school's definition of travel distance, so the concession applies — the missed days are made up later, which the four schools agree on. Details of what does and does not invalidate a fast are on what breaks the fast.
Which is better is a genuine difference of opinion rather than a settled matter. The Companions travelled with the Prophet ﷺ in Ramadan, some fasting and some not, and neither group criticised the other (reported by Bukhari and Muslim). The majority of scholars — Hanafi, Maliki and Shafi'i — hold that fasting is better for a traveller who finds it easy; Hanbali scholars hold that taking the concession is better. All agree that if fasting becomes a hardship, breaking it is the better course. A seventeen-hour fast in a dry cabin is a fair candidate for that description.
One detail catches daytime departures. If you woke up at home, began the fast as a resident and left later that day, the Hanafi, Maliki and Shafi'i schools hold that you should complete that day's fast; the Hanbali school permits breaking it once you have left the town. From the next day onwards, the concession is fully yours on every view.
The same logic of sunset, not clock, drives the very long summer fasts of the far north — see Ramadan fasting at high latitude. For prayer on the same flight, including the qibla swing and praying seated, see praying on a plane.
On the ground the same questions have reference answers: what breaks the fast, suhoor and iftar the Sunnah way, and the dua for breaking the fast. For the prayers on the same flight, read praying on a plane and shortening and combining prayers when you travel; the dua for travel is worth saying at take-off.
Common questions
- When do I break my fast on a plane?
- When the sun sets as seen from the aircraft. Not at your departure city's Maghrib, not at your destination's, and not at the sunset of the ground below — at cruising altitude the sun stays visible for roughly 12 to 47 minutes longer than it does on the ground beneath, depending on latitude and direction.
- Why is my fast so much longer flying west?
- Because the aircraft is moving with the sun. On an illustrative London to New York flight leaving at 15:00 on 22 February 2027, the sun did not set from the aircraft until 7 hours 50 minutes into the flight, making a fast of 17 hours 39 minutes against 12 hours 18 on the ground in London.
- Can I skip fasting because I am flying?
- Yes. A traveller may leave the fast and make up the days later (Quran 2:184). Scholars differ on whether fasting or not is better when it is easy, but all agree breaking is better when fasting becomes a hardship. If you began the day fasting at home before leaving, the Hanafi, Maliki and Shafi'i schools hold you should complete that day.
- What if I cannot see whether the sun has set?
- Ask the cabin crew or check the aircraft's position against a sunset calculation, and if you are still unsure, wait until you are confident. A fast broken before sunset by mistake must be made up.