A technical error in Switzerland's air traffic control systems, introduced when a newly designated restricted zone around Buergenstock was incorporated into radar display software, led to flight disruptions at Zurich airport on Sunday, authorities said.
Skyguide, the Swiss air traffic control authority, said the fault emerged after controllers integrated the restricted zone created to secure peace talks between the United States and Iran into their radar displays. The zone covered the Buergenstock mountain resort, the location selected to host the negotiations.
Skyguide noted the restricted area had been decided at the last minute because the decision to hold the latest round of talks was not finalised until Saturday. The authority said the technical problem has since been addressed and normal operations resumed. "The systems are running smoothly, and security was ensured at all times," Skyguide added.
An airport spokesperson told Reuters that by mid-day 12 arrivals and 14 departures had been cancelled and that at least 60 departures experienced delays. Skyguide said the issue was a technical fault in air traffic control triggered by the security measures surrounding the talks.
The diplomatic meeting at Buergenstock proceeded on Sunday with U.S. Vice President JD Vance arriving for discussions with Iran as set out in a tentative peace deal. However, the talks were overshadowed by Iran's announcement that it had reimposed its blockade of the Strait of Hormuz.
Switzerland had promised a "discreet and reliable setting" for the negotiations taking place at the resort, which lies just over 50 kilometres (31 miles) south of Zurich airport as the crow flies. Authorities emphasised that security around the talks was maintained while technical teams worked to remedy the radar issue.
Airport and air traffic control officials said services were back to normal following the fix, with systems operating without further incident. The disruption illustrates how last-minute security measures around high-profile diplomatic events can intersect with technical systems that support commercial aviation.
Summary
A last-minute restricted airspace over Buergenstock, introduced for U.S.-Iran peace talks, was integrated into radar displays and caused a technical fault in Swiss air traffic control. The glitch led to cancellations and delays at Zurich airport before being resolved; flights and systems have returned to normal. The talks continued amid renewed regional tensions after Iran announced a blockade of the Strait of Hormuz.