Istanbul Airport to Open Fourth Main Runway on September 18, Adding First East-West Corridor

Istanbul Airport is scheduled to open its fourth main runway on September 18, 2025, bringing its total runway count to six — four main and two auxiliary. The new runway measures 2,820 metres long and 45 metres wide and runs on an east-west orientation, the first such alignment at the airport; all existing main and auxiliary runways there run broadly north-south.

Turkish authorities say the east-west alignment is intended to give air traffic controllers greater operational flexibility, particularly when wind conditions reduce the efficiency of the existing runway configuration. They also say the runway's location will benefit aircraft operating toward eastern destinations and certain domestic services, since shorter taxi distances can reduce journey times, fuel consumption and ground-waiting periods, and that its proximity to maintenance and hangar areas is expected to make some general aviation and technical movements more efficient.

The opening follows an operational milestone on April 17, 2025, when Istanbul Airport became the first airport in Europe to conduct simultaneous independent operations on three runways, enabling three aircraft to take off or land at the same time on separate runways. Turkish authorities have indicated the new runway will also contribute to the infrastructure required for potential future simultaneous independent operations across four runways, though they note additional operational, airspace and technical work would be required before such a system could be introduced.

The runway addition comes during a strong period for Istanbul Airport. In July 2026, the airport handled 8.15 million passengers, surpassing London Heathrow's 7.86 million to become Europe's busiest airport by passenger traffic for that month; Istanbul's traffic rose 2.3% compared with July 2025, while Heathrow's declined 1.5%. The airport currently serves more than 340 destinations and is connected by approximately 110 airlines.

Beyond runway infrastructure, Istanbul Airport is undergoing broader expansion. Turkish Airlines launched a programme in January involving more than $2.3 billion in planned facilities covering aircraft maintenance, catering, cargo and logistics. The 485-room Hilton Istanbul Airport hotel opened in August, becoming Hilton's 100th property in Türkiye, and a Jetex IGA C-VIP private aviation terminal also opened earlier in the year.

Adding a runway on a different axis rather than simply another parallel strip is a capacity move aimed at resilience as much as raw throughput: a crosswind option lets controllers keep landing and departure rates up when wind favors an orientation the existing north-south layout cannot serve well. For a hub already running simultaneous independent operations on three runways, a fourth main runway is also the physical groundwork for extending that capability further, even though Turkish authorities themselves note further operational, airspace and technical work stands between the new runway and four-runway simultaneous operations.

The timing matters because Istanbul is not just adding infrastructure in isolation — it is doing so while overtaking Heathrow on monthly passenger volume and while Turkish Airlines pours over $2.3 billion into maintenance, cargo and logistics facilities. Capacity, connectivity and commercial infrastructure are being built out together, which is how a hub airport typically converts a traffic lead into a durable one rather than a single strong month.

What determines whether this becomes more than a capacity headline is the pace at which the airspace and technical work needed for four-runway simultaneous operations actually proceeds, and whether Istanbul's July 2026 lead over Heathrow holds up over subsequent months rather than reflecting a one-off swing in either airport's traffic.