As drones have become more popular and more easily accessible, they pose a serious problem for airports which are testing new measures to ensure air traffic safety.
Last year, the German air traffic control group DFS saw a massive spike in the number of disruptions due to drones. They logged 158 disruptions in 2018, compared to 88 in 2017. Most of the disruptions hit Frankfurt, followed by Berlin's Tegel Airport.
In Germany, it is illegal to fly drones over airport runways, large gatherings, hospitals, prisons and train tracks. In areas where they are allowed, drones are not permitted to fly higher than 100 meters (328 feet). There are certain exceptions for devices that are flown on special airfields for model airplanes.