The cockpit crew of the Boeing 777-300ER aircraft, which was carrying 17 personnel and 293 passengers, found technical problems with a device measuring wind speed and direction as they prepared to take off, the Post previously learned.

The emergency slides were deployed for evacuation, with 11 passengers injured when using them, including two suffering leg fractures.

Videos circulating online show some passengers who reach the bottom of the slide not moving away in time and those coming after colliding with them. In one clip, a man throws his bags down a chute first before sliding.

2. When should emergency slides be deployed?

According to the European Union Aviation Safety Agency (EASA), evacuation slides are used in emergency situations which pose an immediate threat to passengers and crew members on board.

A Cathay pilot, who asked not to be named, said slides would be deployed when an aircraft ditched in the sea or evacuation was carried out on the runway or taxiway where stairs were not available.

For incidents not classified as serious, slide use would be decided by the captain, said a Cathay flight attendant, who wished to remain anonymous. If the captain was unresponsive, the decision would fall to other pilots, followed by flight attendants. During serious incidents, flight attendants next to the emergency exit would make the decision.

3. What are the dos and don’ts of a slide evacuation?

Cabin crew must evacuate passengers as quickly as possible without collecting or storing luggage at the exits, the EASA says.

Opening overhead lockers may result in luggage falling on passengers, obstruct those trying to reach exits and potentially cause injuries, it says. Sliding down chutes holding luggage may also result in passengers being unable to maintain the correct position, potentially leading to injuries. Luggage could also damage the slides.

Cathay’s Safety and Emergency Procedure manual says it is not recommended for passengers to bring their luggage when evacuating via slides.

But it notes, “Despite being told to leave all personal possessions behind, we still see videos of passengers coming down evacuation slides with their carry-on bags. However, what we are actually seeing is one aspect of human behaviour under stress.”

The flight attendant, who has worked at Cathay for eight years, said for a slide evacuation on land, two major rules applied – high-heel shoes had to be removed and no suitcases taken.

“As the slide is inflated, if you jump on it with high heels, they may puncture it and make it unusable,” he said. “If you throw a suitcase down the slide, it can hit other passengers.”

He said instructions for passengers were meant to be simple and concise because evacuation should be carried out as fast as possible. He added aircraft manufacturers suggested an evacuation time of only 90 seconds.

Passengers should cross their arms and place them on their chest when sliding down to prevent injuries, he added.

Warren Chim Wing-nin, a spokesman for the Hong Kong Institution of Engineers’ aircraft division, said carrying bags during an evacuation by slide was “absolutely a wrong move”.

“This is essentially throwing an object from a height that could injure the passengers at the bottom of the slide,” he warned. “In safety demonstration videos … individuals evacuating never bring their luggage with them.”

Chim also said he believed the problematic device on the Cathay aircraft measured airspeed.

4. What if slides are used on water?

When aircraft needed to make an emergency landing on water, slides would be used for evacuation, the flight attendant said.

“We will tell passengers to wear life jackets, then remove their shoes and take no suitcases,” he said. “When they reach the top of the slides, they will be told to inflate their life jackets and crawl down.”

When slides were deployed on water, the angle would be less steep than on land, so passengers would find it easier to crawl, he said.

5. Are injuries common during evacuation by slide?

During emergencies, flight attendants could not ensure every passenger slid down without bumping into others because the priority was to evacuate everyone as fast as possible, the Cathay worker said.

He said even during training, some classmates were injured.

“Some of them may jump and land on the door frame instead of the slide, and injure their back,” he said. “If the slides are too steep, the impact when landing on the ground can be huge, which can injure your legs.”

He said in strong wind, the slides could wobble so the first person down or the flight attendant who sat next to the exit would be asked to hold the chute.

6. What about incidents overseas?

In May 2019, Aeroflot flight 1492 burst into flames killing 41 out of 78 passengers and crew as fire engulfed the rear of the aircraft at Moscow-Sheremetyevo airport after an emergency landing.

Some passengers were seen blocking the aisle and bringing luggage down the slides, which reportedly hindered the evacuation of others.

In 2020, the Royal Aeronautical Society, a professional body dedicated to the aerospace community, urged authorities to look into introducing a requirement to remotely lock from the flight deck overhead bins for taxi, take-off and landing given the number of accidents where passengers had taken baggage with them in evacuations.