In the last two months, at least a dozen European airports—from Brussels to Copenhagen, from Munich to Palma—have had to suspend or delay operations due to sightings of unidentified drones. Between the end of September and the beginning of November alone, more than 35,000 passengers were affected and hundreds of flights were canceled or diverted. The accumulated economic losses are estimated at more than four million euros. With Christmas approaching, when nearly two million flights are scheduled across the European continent, carrying 200 million passengers, further disruptions are feared.