Here's what happens when airlines receive bomb threats

Bomb threats targeting more than a dozen flights in Europe have led to diversions and, in some cases, military escorts, after officials said the incidents were malicious hoaxes. The reports note that hundreds of passengers were affected this week as authorities assessed each alert’s credibility. In line with guidance described by Joji Waites of the British Airline Pilots’ Association, assessors categorize threats as credible, partially credible, or not credible. If a threat is deemed credible, the flight crew is informed immediately and the captain makes decisions using a safety checklist—evacuating when the aircraft is on the ground or prioritizing the safest, quickest landing if already airborne. Aviation security expert Philip Baum said many threats arrived by email and that disrupting flights can cost airlines up to $250,000.