What happens when a pilot receives a bomb threat?

A series of bomb threats has forced passenger aircraft to divert across Europe, raising questions about what happens in the cockpit when pilots are warned that an explosive device could be on board.

Flight crews are trained to respond to security emergencies, working with air traffic control, airlines operations teams and specialist authorities to protect passengers and crew.

Depending on the circumstances, the response can involve an aircraft diversion, military assistance and extensive security inspections.

How is a pilot alerted to a bomb threat?

Bomb threats can be received before departure or while an aircraft is airborne. They may be communicated to pilots by their airline’s operating team, or directly through air traffic control.

If a threat is considered sufficiently serious, relevant information is passed to the flight crew, potentially through an aircraft datalink message or air traffic control.

Emma Henderson MBE, former airline captain and aviation expert, told Aerospace Global News: “Our priority is always to keep people safe, so any threat has to be treated seriously every single time.”

What do pilots do when a bomb threat is reported?

Once alerted, the captain and first officer follow their specific airline’s security procedures and checklists.

They would also usually use squawk 7700 to tell air traffic control that there is an emergency. In an “unlawful act of interference”, for example a hijacking or someone taking control of the aircraft, they will likely squawk 7500 instead.

Why might pilots divert rather than continue to their destination?

If the bomb threat is considered credible, the aircraft will normally divert to a suitable airport and land as quickly and safely as possible.

The nearest airport is not always the best option. Pilots will always take into account runway availability, weather, aircraft condition and emergency facilities.

The amount of fuel on board can also affect the decision. An aircraft diverting early on a long-haul flight may still be carrying a lot of fuel, making it heavier than the maximum weight normally allowed for landing. However, if there is a security emergency, the pilots may have to land regardless of the extra weight.

How does air traffic control handle an aircraft bomb threat?

Air traffic controllers receive specific training for incidents involving potentially explosive devices. They coordinate priority handling, maintain appropriate separation from other aircraft and help organise the diversion.

Controllers are also aware that pilots may be under considerable pressure and managing an increased cockpit workload. Clear communication and coordination with emergency services are therefore essential.

When do fighter jets get involved?

Military fighter aircraft may be scrambled to identify or escort a commercial airliner if additional monitoring is deemed necessary. In the UK, the RAF maintains Quick Reaction Alert (QRA) arrangements, with Typhoon aircraft based at RAF Coningsby and RAF Lossiemouth.

A fighter escort is not automatic and does not mean an explosive device has been confirmed. It is an extra security measure available to military and civilian authorities.

What do cabin crew do during a bomb threat?

Cabin crew look after passengers while following the airline’s security procedures. They communicate with the flight deck, manage the cabin and help passengers remain calm.

If a suspicious item is reported, they follow their training and instructions rather than attempting to investigate or handle it themselves.

How are passenger aircraft designed to reduce the risks of an explosion?

Aircraft manufacturers also evaluate security when designing and building passenger planes.

One example is the Least Risk Bomb Location (LRBL), which is part of certain aircraft safety requirements. It involves considering where an onboard explosion could have the least impact on the aircraft and how important structures and systems can be better protected. The US Federal Aviation Administration (FAA) provides guidance on this in its Advisory Circular AC 25.795-6.

Manufacturers also look at how the aircraft is built and how its cabin pressurisation system works. This system keeps the air pressure inside the cabin at a safe and comfortable level for passengers and crew while flying at high altitudes.

What happens to passengers after an emergency aircraft diversion?

After landing, the aircraft will usually be directed to an isolated parking position away from other aircraft and terminal buildings.

Depending on the circumstances, the captain may initiate a Precautionary Rapid Disembarkation, so passengers can leave using mobile steps or stairs rather than emergency slides, which can cause injuries.

If a suspicious item or suspected explosive device is discovered, a more urgent evacuation may be necessary. Specialist teams, potentially including Explosive Ordnance Disposal (EOD) personnel, may inspect the aircraft, baggage and cargo. Further security screening is also likely to be needed before the aircraft can return to service.

“Complacency is never an option”

A bomb threat can disrupt far more than the flight involved. Diversions affect airport schedules, connecting services, aircraft availability and crew planning.

Inspections, crew changes, passenger rebooking and schedule adjustments can have knock-on effects across an airline’s network.

Emma Henderson MBE added:

“From a passenger point of view there is a clear intent to disrupt rather than harm and we can’t bow to the fear that might be creating. We must maintain confidence in air travel while ensuring every warning is taken seriously.”

Crew training, aircraft certification, airport security and cooperation between authorities all contribute to aviation safety.

Another current airline captain we spoke to explained:

“Security and safety are taken extremely seriously by airlines and airports. Flight crews, cabin crews and many airline ground personnel receive regular and thorough security training, keeping them informed on the latest developments and threats within the AVSEC (aviation security) domain and how to deal with them.”

He added: “Ultimately, the objective is to assess every threat, protect passengers and crew, and ensure the necessary security checks are completed before normal operations resume. Even when warnings prove unfounded, complacency is never an option.”