Why there was concrete wall near runway that expert labelled 'defining moment' in plane crash that killed 179 people

An investigation is underway into the Jeju Air crash which killed all but two of the 181 people on board.

Authorities in South Korea are working to determine exactly what caused the tragic plane crash at Muan International Airport on Sunday (29 December) morning local time.

Shocking footage of the incident appeared to show the Boeing 737-800 jet skidding across the runway without having deployed its landing gear.

It then collided with a concrete wall near the end of the 2,800m runway and burst into flames.

The pilot of the plane, which had departed from Bangkok, Thailand, reported that it had struck a bird before the deadly crash, according to the BBC.

Investigators are now trying to find out what other factors may have played a part in the incident, including whether the aircraft’s control systems were disabled.

The plane's black box has been retrieved from the wreckage, but is missing a key connector which will delay the data extraction from it, South Korea's transport ministry said.

However, analysis of the cockpit voice recorder has now begun, which will hopefully provide a clearer picture of the final moments on board.

The Jeju Air plane burst into flames after smashing into a concrete wall (Chris Jung/NurPhoto via Getty Images)

Aviation experts have also been questioning why the 'unusual' concrete wall was located near the end of the runway.

The four-metre tall dirt-and-concrete embankment at the South Korean airport was part of a guidance system, which helps pilots land when visibility is poor or at night.

But according to David Learmount, who is the operations and safety editor of Flight International magazine and an aviation boffin, it's positioning proved to be the 'defining moment' of the tragedy.

He believes that if the Boeing 737-800 had not hit the wall, it would have instead gone through a perimeter fence and across a road before coming to a stop in a nearby field.

"To have a hard object about 200m or less into the overrun, I've never seen anything like this anywhere ever before," he told Sky News.

"There was plenty of space for the aircraft to have slowed down, come to a halt.

"And I think everybody would have been alive...the pilots might have suffered some damage going through the security fence or something like that.

"But I even suspect they might have survived."

Lufthansa pilot Christian Beckert described the concrete wall as 'unusual' to Reuters, saying: "The reason so many people died was not the landing as such, but the fact that the aircraft collided with a very hard obstruction just beyond the runway end.

"Normally, on an airport with a runway at the end, you don't have a wall."

Aviation experts have been sharing their thoughts on the incident (X)

According to South Korea's Yonhap News Agency, a navigation system which assists aircraft landings - known as a localiser - is inside of the concrete structure.

It is reported to have been raised and covered with dirt to keep this system level and ensure it works correctly.

At most airports, the instrument landing systems are placed on collapsible structures.

Another pilot with 48 years of experience, Chris Kingswood, explained that obstacles that are located 'within a certain range and distance of the runway' are required to be breakable.

"Which means that if an aircraft strikes them that they do break," he told the BBC. "It does seem unusual that it's such a rigid thing."

He said that the alternate outcomes of the crash, specifically what might have happened if the wall wasn't there, will 'certainly [be] something that will be investigated'.

Kingswood added: "Aeroplanes are not strong structures - they are, by design, light to make them efficient in flight.

"They're not really designed to go high-speed on its belly, so any kind of structure could cause the fuselage to break up and then be catastrophic."

Discussion is also mounting around whether the pilots of the fateful Jeju Air flight even knew the barrier was there.

Aviation analyst Sally Gethin added: "We need to know, were [the pilots] aware there was this hard boundary at the end?

"If they were directed by the control tower to reverse the use of the runway the second time around, that should come out in the investigation of the black boxes.

"I think there are so many questions."

What have Jeju Air and Boeing said about the crash?

In a statement, Boeing said: "We are in contact with Jeju Air regarding flight 2216 and stand ready to support them. We extend our deepest condolences to the families who lost loved ones, and our thoughts remain with the passengers and crew."

Jeju Air also added: "We deeply apologize to all those affected by the incident. We will make every effort to resolve the situation. We sincerely regret the distress caused."