A British Airways crew member accidentally deployed the aircraft’s emergency slide, delaying hundreds of passengers for hours. 

On Monday, a British Airways flight from London’s Heathrow Airport to Brussels was being prepared for service when the incident occurred. 

No passengers were on board at the time, although they were delayed around three hours after the Airbus A320 was taken out of service and a new aircraft was arranged to take them to Brussels. 

The blunder was first reported by the Sun, which said the incident was likely to have cost the airline £100,000 ($218,034). 

A source told the Sun: “The crew member wasn’t thinking and made the most basic of errors by deploying the emergency slide while on the ground at Heathrow. 

“It’s a minimum £100,000 mistake and knocked out services for the rest of the day. 

“This error is not easy to achieve.” 

In a statement to the Sun, BA said: “We apologised to customers for the delay and our teams worked hard to arrange a replacement aircraft so customers were able to travel with us as planned.” 

Footage of the incident showed emergency services stationed by the aircraft which had the inflatable slide extending from the fuselage. 

According to Airbus' safety magazine, Safety First, one way of deploying a slide on an A320 Family aircraft requires removing a safety pin, moving a lever into the armed position, and then opening the door to trigger deployment. 

Accidental emergency door activations are very costly for airlines. Rectifying it involves repacking and safety checks by engineers. 

An unintentionally activated emergency slide that is attached to an air bridge can cause the door to be ripped off and block exits, taking planes and docking bays out of service. 

Last February, a British Airways pilot was reportedly stood down after accidentally triggering the emergency exit on a busy A320. 

A 22-year-old was piloting a service that had arrived from the Czech Republic at Heathrow Airport for a quick turnaround to Bucharest, reported the Sun. 

The error allegedly cost the airline £50,000 ($100,000) and a new rubber slide.