The Northern Arc: How Europe-Asia Flights Route Through the Caucasus and Central Asia Around Iran
Look at a live flight map on any evening in autumn 2026 and you will see two rivers of traffic between Europe and Asia. One runs south, down the Red Sea and across Saudi Arabia and Oman. The other runs north-east, over Turkey, squeezes through a narrow gap between Russia and Iran, and fans out across the Caspian into Kazakhstan and the rest of Central Asia. Pilots and planners call that second river the northern arc.
We have written about [the southern corridor](/blog/southern-corridor-egypt-saudi-arabia-flight-routes) and about the general question of [alternative routes avoiding Middle East airspace](/blog/alternative-flight-routes-avoiding-middle-east-airspace). This post is about the northern option specifically: where it goes, why a 137-kilometre-wide gap in the Caucasus has become one of the most important pieces of sky in the world, what the route costs you as a passenger, and how to check whether your own flight is on it.
Why there is a northern arc at all
Before 2022, a flight from Frankfurt to Tokyo or Delhi had a choice of great-circle routes across Russia and, further south, across Iran. Russia's airspace closed to most Western carriers after the invasion of Ukraine. Iran's airspace, after the 2025 strikes and the renewed US-Iran fighting that flared again at the start of September 2026, is technically open above FL285 on a few routes but is avoided by most foreign operators and formally warned against by EASA. Iraq is open but unloved; Syria is reopened but thinly controlled.
Take Russia and Iran off the map and the direct corridor between Europe and Asia disappears. What remains is a band of usable airspace to the south (Egypt, Saudi Arabia, Oman) and a thinner band to the north: Turkey, then Georgia, Armenia and Azerbaijan, then the Caspian Sea and Central Asia. The northern band is what has turned into the arc.
The Ganja Pass: the pinch point
The critical stretch is over Azerbaijan. Between the southern edge of Russian airspace and the northern edge of Iranian airspace lies a corridor that is roughly 85 miles, about 137 kilometres, wide at its narrowest point. It is named for the Azerbaijani city of Ganja beneath it, and it is the only way to get from the Black Sea side of the Caucasus to the Caspian side without entering either closed airspace.
The numbers show how hard that gap is working. Azerbaijani airspace handled about 78,100 flights in the first half of 2023 and about 125,600 in the first half of 2025. During the Iranian closures of 2025, Azerbaijan absorbed more than 100 extra flights a day at short notice, and by early 2026 as many as 1,000 flights a day were passing through the corridor. A single sector of sky is carrying a meaningful share of the planet's Europe-Asia traffic.
That concentration is the arc's main weakness. If the Ganja Pass were ever closed, by weather radar outages, a regional incident, or political decision, the only alternatives would be the long southern loop around the Arabian Peninsula or polar routings, both of which add hours.
Where the arc goes after the Caucasus
Once across the Caspian, flights spread out according to destination. The main beneficiary is Kazakhstan, whose airspace handled 216,616 flights in the first half of 2025, of which 161,029 were foreign airlines in transit or landing. It has 124 air traffic service routes with a combined length of 113,530 kilometres, and a safety-compliance score of 95.7 percent against international standards, which is part of why European regulators are comfortable sending their carriers through it.
From Kazakhstan the arc branches. Flights to China and Japan continue east across Kazakh and then Chinese airspace. Flights to India, Thailand and beyond turn south-east over Uzbekistan and Turkmenistan, and here the second pinch point appears: Afghanistan. The Kabul flight information region operates as uncontrolled Class G airspace with no normal air traffic service. Crews cross on published contingency routes using pilot-to-pilot broadcast procedures, and Afghanistan charges a flat fee of 700 US dollars per crossing. Many airlines accept that; others swing wider over Pakistan or drop south to pick up the Gulf corridor instead.
- Europe to East Asia: Turkey, Georgia or Armenia, the Ganja Pass, Caspian Sea, Kazakhstan, then China or Mongolia.
- Europe to South Asia: the same path to the Caspian, then Turkmenistan or Uzbekistan, then either Afghanistan's contingency routes or a detour around them into Pakistan.
- Europe to the Gulf and East Africa: usually not the arc at all; the southern corridor over Egypt and Saudi Arabia is shorter.
What it costs you as a passenger
The honest answer is: less than the southern loop, more than the old direct route. Uzbekistan Airways' Tashkent-Munich service is a useful yardstick, because the airline began rerouting around Russia and Belarus in January 2025 and published the effect: the route grew from 4,849 kilometres to 5,156 kilometres, adding 30 to 40 minutes to each flight. For a London-Delhi or Paris-Bangkok sector the penalty is in the same range, typically 30 to 60 minutes, depending on winds and how far south the aircraft has to go around Afghanistan.
There are second-order costs that do not show on the timetable. The arc is congested, so flow restrictions and ground delays at departure are more common than they were. GPS jamming and spoofing, which we covered in our post on [GPS jamming and spoofing in 2026](/blog/gps-jamming-spoofing-flights-2026), are widespread across the Gulf and have been reported along parts of the Black Sea and Caucasus too; crews are trained for it, but it is one more reason the route is flown conservatively. And because Central Asia is not one integrated aviation market, a problem in one country's air traffic system cannot simply be absorbed by its neighbours.
How to tell if your flight uses the northern arc
You do not need special tools, just a flight-tracking site and five minutes.
- Look up your flight number on a tracking site and open the playback for the same flight on recent days. A northern-arc flight will cross Turkey, bend north of the Iranian border near the Caspian, and continue over Kazakhstan or Turkmenistan. A southern-corridor flight will follow the Mediterranean, Egypt and the Red Sea.
- Check the scheduled block time against the same route a few years ago. A 30 to 60 minute increase on a Europe-Asia sector is the signature of a reroute; it does not tell you which one, but combined with the map it will.
- If the flight is to India or South-East Asia, watch what the track does around Afghanistan. A straight line across suggests the contingency routes; a dog-leg over Pakistan or down to the Gulf suggests the airline is avoiding them.
- For the regulatory picture behind any of this, our guide to [how to check if your flight avoids conflict zones](/blog/how-to-check-if-your-flight-avoids-conflict-zones) walks through the EASA bulletins and the NOTAMs that airlines are responding to.
Is the northern arc safer than the south?
Safer than Iran, Iraq or Syria: clearly, which is the point. Safer than the southern corridor: not obviously, and the question is slightly wrong. Both corridors are made of airspace that regulators consider acceptable; the difference is in the texture of the risk. The south is close to active conflict zones in the Gulf and the Red Sea, with heavy GPS interference and flow measures across Saudi Arabia, Qatar, the UAE and Oman. The north is far from any active conflict but is structurally fragile: one narrow pass, one uncontrolled FIR, and a chain of national air traffic systems with uneven capacity.
Airlines weigh those trade-offs every day and often split their networks: East Asia flights north, Gulf and East Africa flights south, India flights wherever the winds and the Afghanistan question favour that week. As a passenger, the most useful thing to know is that neither corridor is a compromise on safety; both are a compromise on time.
What would change the picture
Two things. A durable reopening of Iranian airspace to foreign carriers would pull a large share of South Asia traffic back off the arc almost immediately, which is why we track [the signals that Iran's airspace might reopen](/blog/will-iran-airspace-reopen-signals-to-watch) in a separate post. And any disruption to the Ganja Pass or to Kazakh transit capacity would push traffic south, lengthening everyone's flights at once. Neither looks imminent in October 2026; the arc is, for now, the default rather than the detour.