A technical failure at Swiss air traffic control prevented all departures from the country's largest airport for two hours on Monday, causing delays to some 60 flights, Zurich airport said.
The malfunction affecting the air navigation service provider Skyguide occurred between 2:30 and 4:30pm local time (1230 and 1430 GMT).
"This had an impact on the office IT systems and, among other things, also on the incoming flight plans and meteorological data," Zurich airport said in a statement.
Landings were able to continue without any problems, with departures resuming again at 4:30pm.
"Due to the disruption, at least 60 flights have been delayed between 20 and 100 minutes, affecting around 6,600 passengers," Zurich airport said, adding that no flights had to be cancelled.
Zurich Airport is the largest in Switzerland, with almost 3 million passengers passing through last month.