the threat against flight 826 from cologne bonn to milan 's malpensa airport was received on sunday evening .
the tower in cologne immediately alerted the pilot of the airbus a320 , which was taxiing toward the runway at the time , germanwings said .
the threat was emailed to the airport 15 minutes before the plane 's scheduled departure , prompting police to set the necessary measures in motion .
the threat was received as the pilot was taxiing along the runway at cologne bonn airport .