Malpensa airport in Milan was closed today after a drone was spotted flying near the runway, according to local reports.
The drone sighting led to flights being diverted to other airports as the emergency closure sparked chaos around 11am local time.
A Twitter user who was affected said his easyJet flight to Luton was grounded just before takeoff at Milan. The crew said a drone has been seen on the runway.
And a BA flight from Heathrow was forced to circle northern Italy for 20 minutes before being allowed to land at Malpensa, The Sun reports.
After a number of diversions, departures and arrivals began returning to normal but knock-on delays were expected across Europe.
It comes a month after another drone sighting at Malpensa on March 3.
Just over a week ago a drone caused mayhem at Frankfurt airport. Also, in December 2018, just before Christmas, Gatwick was brought to a standstill for three days by reported drone sightings.
In January flights were suspended by a drone sighting at Heathrow and in February a drone grounded planes at Dublin.