Heathrow’s hold on the title of Europe’s busiest airport has been under sustained pressure from Istanbul, and the margin between the two hubs has become increasingly difficult to ignore. Istanbul finished 2025 only about 40,000 passengers behind Heathrow, then opened 2026 ahead, handling 6.9 million passengers in January compared with Heathrow’s 6.5 million, according to Airports Council International Europe. Heathrow recovered its lead as the year progressed, but the advantage remained slim.

In May, just 3,012 passengers separated the two airports, and by the end of June Heathrow had handled 40 million passengers during the first half of the year, compared with 39.84 million at Istanbul. The figures reflect two major European hubs moving through 2026 on almost parallel tracks, even as Heathrow operates close to the limits of its existing runway capacity and Istanbul continues to add infrastructure. By July, Istanbul had pulled ahead, handling more passengers than Heathrow and taking the monthly lead among Europe’s airports.

Istanbul Airport Handles More Than 8.1 Million Passengers In July

Turkey’s Ministry of Transport and Infrastructure reported that Istanbul Airport handled 8,146,411 passengers in July, based on official airport traffic figures. Domestic traffic accounted for 1,816,429 passengers, while 6,329,982 traveled on international routes. Heathrow recorded about 7.86 million passengers for the month, leaving Istanbul ahead by nearly 290,000 passengers.

The July figures also moved in opposite directions from a year earlier. Euronews stated that Heathrow’s passenger traffic fell 1.5% from July 2025, while Istanbul’s increased 2.3%. Heathrow’s Middle East routes recorded a 20.2% year-over-year drop as conflict in the region continued to disrupt flight schedules and demand. Those pressures had already appeared in Heathrow’s first-half results. The airport reported a 25% decline in Middle East passenger traffic during the first six months of 2026. North American traffic increased 1.6%, Asia-Pacific traffic rose 7.9%, and connecting passenger numbers increased 5.4%.

Across Europe, passenger traffic rose 2.6% during the first half of 2026, while growth slowed from 4.3% in the first quarter to 1.3% in the second, ACI Europe figures show. “There is no escaping the fact that geopolitics have increasingly been shaping traffic performance this year,” said ACI Europe Director General Olivier Jankovec.

Heathrow Pushes Expansion As Istanbul Adds Runway Capacity

As passenger traffic tightens the race between Europe’s two leading hubs, Heathrow and Istanbul are also moving ahead with plans to handle more travelers. Heathrow says its two runways are operating at 99% of capacity and continues to pursue a third runway as demand presses against the limits of its existing infrastructure. The proposal would expand terminal facilities and raise Heathrow’s annual capacity to as many as 150 million passengers, the airport says.

While Heathrow’s third runway remains a proposal, Istanbul is closer to opening its fourth main runway. Turkey’s Ministry of Transport and Infrastructure says construction on the airport’s fourth main runway is nearing completion, with operations expected to begin in the final quarter of 2026 after technical testing. The new runway would support an airport that has continued to record faster passenger traffic growth than Heathrow in recent years.

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