South Korea's transport ministry cut construction costs and approved improper airport safety structures for more than two decades, the state auditor said in a report on aviation safety management after a Jeju Air crash that killed 179 people.

The December 2024 crash involved a Boeing 737-800 which was struck by birds, belly-landed and overran the runway at Muan International Airport, killing almost everyone on board after it struck a concrete support for a localiser antenna. The only survivors were two flight attendants at the rear of the plane.

The Board of Audit and Inspection said in a report published on Tuesday that the ministry built a 2.4 metre (7.9 ft) high concrete embankment upon which to place the localiser - a landing guidance system - at Muan airport in order to reduce earthwork costs, without adequately reviewing relevant rules.

Under international standards, localiser structures should be designed to break apart easily upon aircraft impact.

The ministry is responsible for airport construction. It hands operations to Korea Airports Corp (KAC) ICNP.UL but remains responsible for safety certification.

The auditor said the ministry wrongly approved 14 non-compliant localiser installations at eight airports including Muan, Gimhae and Jeju. It also said that, for up to 22 years, the ministry certified operating permits and approved regular inspections that erroneously found frangibility standards had been met.

It identified broader shortcoming in bird-strike prevention and other aspects of air safety management, and notified the ministry of 30 cases of wrongdoing or procedural failure.

The Ministry of Land, Infrastructure and Transport said it "humbly accepted" the findings and would take strict follow-up measures, including localiser improvement and stronger bird-strike prevention.

A KAC spokesperson said the airport operator is in the process of reflecting improvements recommended by the report.

Jeju Air 089590.KS did not answer phone calls seeking comment.

A separate government-commissioned report found the crash might not have been deadly if there had not been a concrete embankment at the end of the runway, an opposition lawmaker said in January, citing a simulation contained in the report.

A full investigative report is pending public disclosure. It has missed a one-year deadline for the release of a progress report.

The Muan airport has been closed since the crash. It is unclear when it will reopen.

-Joyce Lee/Reuters