The drone attack that shut down Gatwick Airport in London just before Christmas is believed to have been an “inside job,” The Times of London reports, and was possibly carried out by an angry employee. The shutdown caused chaos, with flights unable to take off or land and an estimated 110,000 passengers on 760 flights being grounded. The perpetrator has never been caught—a husband and wife were arrested after being wrongly suspected of the crime and vilified in the British press. The operator’s apparent knowledge of the site makes investigators believe a staff member was involved. “[The drone pilot] knew the blind spots for it, where it could not be ‘hit.’ It was clearly someone with really good knowledge of Gatwick, someone who had worked there. Hypothetically it could have been a disgruntled employee,” a source with knowledge of the investigation is reported to have said. Meanwhile, Dublin Airport was forced to temporarily suspend flights Thursday morning after a drone was spotted over the airfield.