More than a dozen flights vanished from radars for almost half an hour earlier this month, according to Austria’s flight safety monitor. The 13 aircraft suddenly disappeared from air traffic controllers’ radar screens in Austria on June 5 and 10, confirmed Austro Control’s Marcus Pohanka. Unseen for 25 minutes on each day, air traffic controllers in neighbouring Germany (Karlsruhe and Munich) and the Czech Republic (Prague) also reported similar troubles. Pohanka didn’t disclose which airlines and aircraft were involved, but hinted that some could have been passenger jets due to the height they were flying. Describing the two incidents as “unprecedented”, Pohanka stated that there was no danger at any time. Almost immediately, extra air traffic controllers were brought in, measures to establish voice contact were initiated and flight corridors were widened. Citing an unnamed expert, one Austrian newspaper has reported that a potential cause may have been interference between the aircraft transponders and ground control. EASA has been called in to investigate the incidents.