Takeaways From the Times Investigation Into the Jeju Air Crash

Seven months after Jeju Air Flight 2216 crashed at Muan International Airport in South Korea, the cause of the accident is still being investigated.

The crash — the worst aviation disaster on Korean soil, with 179 dead — came shortly after the pilots reported a bird strike. Investigators are also looking into whether the pilots may have erred by shutting down the less-damaged engine after colliding with the birds.

But the high death toll may owe more to circumstances on the ground. After crashing on its belly without its landing gear deployed, the plane skidded along the runway and slammed into a concrete wall before bursting into flames.

“There is a cause for the accident and a separate cause for death,” said Lee Jun-hwa, an architect based in Seoul who lost his mother in the crash.

A New York Times investigation found that a series of design and construction choices led to the presence of the concrete hazard close to the runway. Government regulators ignored a safety warning, making a disastrous outcome of any collision more likely.

Reporters for The Times obtained blueprints and other design documents and asked five experts to review them. They also combed through documents issued by Korean authorities over the last 26 years.

The reporting found that the problems began even before the airport opened for service. The original master plan, issued in 1999, called for breakable foundations to anchor navigation antennas, known as localizers, in order to “minimize fatal damage to an aircraft in the event of a collision.” This aligned with recommendations from the International Civil Aviation Organization, a United Nations agency.

What prompted the design change is not clear, but experts said that concrete was a common choice on construction sites because it is cost effective.

The problem was compounded when government regulators signed off on the construction despite knowing that the unbreakable foundation walls posed safety risks, documents show.

In May 2007, six months before Muan International Airport opened, the Korea Airports Corporation, a state-owned enterprise that supervises airports, warned that the foundation walls were too close to the runway. But the Ministry of Land, Infrastructure and Transport dismissed the warning and allowed the airport to open.

In a third misstep, the ministry missed a chance years later to fix the problem during mandatory renovation works. Instead of moving the wall or replacing it with frangible materials, the design company hired for the renovations, Anse Technologies, added a reinforced concrete slab on top of the existing foundation.

The companies in the consortium that built the airport did not answer detailed questions from reporters. One design company told reporters that it no longer had relevant documentation because the project was too old.

Anse Technologies, which was responsible for the renovations, did not respond to questions, either. The company designed localizer structures at three other Korean airports, two of which were later found to have safety problems.

Government regulators, who have wide discretion to interpret and enforce international standards, did not answer detailed questions, citing an ongoing police investigation.

The safety lapses were not confined to the Muan airport. Officials have since discovered problems at six other Korean airports where solid structures stand close to runways.

There were other issues at Muan International Airport, too. Airport managers did not do enough to repel birds near the airport, even though it is surrounded by bird habitats, and they ignored warnings about the dangers, The Times has previously reported. That made bird strikes more likely during takeoff and landing, according to experts.

As authorities attempt to unravel the accident’s cause, the concrete wall itself has become the focus of multiple investigations. In June, police said they were investigating 24 people including government officials who were responsible for “air traffic operations, bird strike prevention and airport facility management.”