Bomb threats divert flights in Europe: what pilots do when they receive an alert

Hundreds of airline passengers in Europe were affected by flight diversions or received military escorts this week following a series of bomb threats that authorities say were malicious hoaxes.

So far, it is unknown who is behind the threats, which came at a time of rising tensions with Russia and warnings that Moscow could intensify so-called hybrid attacks in Europe.

Here is what happens when airlines receive bomb threats.

Threats are assessed and then communicated to the pilots.

Assessors determine if a threat is credible, partially credible, or not credible, according to Joji Waites, director of flight safety, policy and regulation at the British Airline Pilots' Association.

If it is deemed credible, the flight crew is informed immediately and the captain makes all decisions, guided by a safety checklist, Waites explained. If the aircraft is on the ground, that would mean an evacuation. If it is already in flight, the priority would be to land as soon as possible and in the safest way possible.

“Pilots are highly trained and qualified professionals. Their experience is invaluable in ensuring the safety of passengers and keeping aviation one of the safest forms of transport that exists,” Waites stated.

Generally, airlines, airport operators, and law enforcement follow guidelines developed by the European Union Aviation Safety Agency and the International Civil Aviation Organization, which conducts audits to ensure compliance.

Flight crew training includes live situational exercises that cover various threats, including how to look for explosives that may have been smuggled on board.

Diverting and inspecting flights is expensive

When threats are received by phone, airline employees are instructed to keep the caller on the line and gather as much information as possible, according to aviation security expert Philip Baum.

Many of the threats received this week were sent by email, with enough information for authorities to determine that the aircraft needed to be inspected. That can be costly for airlines.

Baum, a visiting professor of aviation security at Coventry University in England, noted that diverting a flight because of an unruly passenger or a bomb threat can cost up to $250,000.

He added that the costs could be lower in this case because most of the affected flights were short-haul, where there is less likelihood of overnight delays.

Unfounded threats could test defenses

The intention of these threats “seems to be to sow chaos and uncertainty about the reliability of air traffic across Europe,” said Jacob Funk Kirkegaard, a senior fellow at the Bruegel think tank in Brussels.

The threats could also be testing the relative response time and level of coordination between authorities in different countries, with the goal of identifying weaknesses for future attacks.

“Do the authorities in Poland respond with the same speed and with the same urgency, etcetera, as the authorities in Italy, for example?” Kirkegaard asked, comparing this type of threat to a “stress test” of the system.