Passengers due to arrive at an airport were diverted after drone sightings near Download Festival.
East Midlands Airport said two passenger flights were diverted to Leeds and Manchester on Friday afternoon.
It follows drone-related disruption to night-time cargo flights on Wednesday and Thursday.
The airport, Leicestershire Police and the festival said they were closely monitoring the situation.
In a joint statement, they said: "Both the festival organisers and the police have enhanced the number of patrols on site and the surrounding areas.
"The public are reminded that flying a drone in proximity to an operational airport is an offence under the Civil Aviation Act 1982 and is a huge risk to public safety. The police will take appropriate action if necessary."
The three-day rock and metal festival is taking place until Sunday at Donington Park, Leicestershire, about one mile (1.6km) from the airport.
Liz Haslem, from Derbyshire, had just landed at East Midlands Airport after being diverted on her way back from Malaga, Spain.
She said: "The pilot announced there were drones in the area from Download Festival so we were rerouted to Leeds.
"At first we didn't know if we were actually going to have to get out at Leeds and make our own way [back].
"We've got our car here at East Midlands, so there there was a bit of confusion and panic to start with."