3 days Ago By Marisa Garcia
The tragic crash of a Jeju Air Boeing 737-800 on Sunday at Muan International Airport, leading to the death of 179 of the 181 people onboard, raised many questions, one of which is why there was a concrete barrier 250 meters from the end of the runway for the aircraft to crash into. Aviation safety expert David Learmount told the BBC that the plane "would have come to rest with most—possibly all—those on board still alive" if the barrier had not been there. The concrete structure was built to raise the ILS localizer beacon, which pairs with cockpit systems to guide aircraft along the runway's axis.
Because the land slopes beyond the runway, Muan International Airport elevated the antenna with a 2-meter-tall structure to ensure an adequate signal in compliance with ICAO requirements. However, the question remains: why was this structure constructed from concrete? As Boeing 737 pilot Chris Kingswood told BBC News: "Obstacles within a certain range and distance of the runway are required to be frangible, which means that if an aircraft strikes them that they do break. It does seem unusual that it's such a rigid thing.
” According to the Yonhap news agency , South Korea’s transport ministry has indicated that other airports, both in South Korea and internationally, also have the equipment installed with concrete structures. Still, Kingswood is right. The 9th edition (2022) of ICAO Annex 14 calls for any necessary equipment installed within 240 meters of the end of the runway to be “frangible”—that can disintegrate on impact—so that it would not pose a threat to aircraft and “mounted as low as possible.
” However, this standard applies to equipment installed within 240 meters from the end of the runway, whereas the structure at Muan Airport is installed 250 meters away. That 10-meter difference could explain why the ILS installation at Muan International Airport is considered compliant. While other factors, including a possible birdstrike and the landing gear failure of the Boeing 737-800 aircraft involved in the accident, will be reviewed, the standards for this ILS structure will likely be part of the investigation.
ILS antenna structures have caused a crash before In 2004, an MK Airlines Limited Boeing 747-244SF operating a cargo flight from Halifax, Nova Scotia, to Zaragoza, Spain, overshot the end of the runway at the Halifax International Airport. The aircraft struck an earthen berm supporting an ILS antenna, and its tail section tore away from the fuselage. The remainder of the aircraft flew another 1200 feet before crashing in flames, leading to the death of seven crew members.
In its final report , the Transportation Safety Board of Canada wrote that the concrete slab on top of the berm, in this case, was at the same level as the runway, but the “localizer antenna projected another 10 feet from the top of the berm.” The transportation safety board added, “There are similar earthen berms in use at other airports in Canada, including one at Fredericton, New Brunswick, and several at Toronto/Lester B. Pearson International Airport, Ontario.
” NAV CANADA submitted an Aeronautical Obstruction Clearance Form to Transport Canada to construct two berms at the airport to support the ILS localizer antennae, which was approved. Some airport personnel raised concerns that the berms might pose a flight risk. Still, after completing an inspection, Transport Canada determined these “were not in conflict with airport certification standards.
” As the regulator stated in a letter to the Halifax International Airport Authority, "Based on information supplied by NAV CANADA, we have determined that the subject localizers are in compliance with airport certification standards. Additionally, clearways are not affected and the existing TODAs [take-off distances available] will remain unchanged..
from an airport certification perspective, we have no concerns about the installation of the new localizers on Runway 06 or Runway 24." ILS antennae are an important element of flight safety, providing pilots with a safe approach to the runway. However, they should not pose a risk to flight safety.
While the berms at Halifax Airport and the structure at Muan Airport were deemed compliant, the industry may need to review the standards for their installation after the tragic Jeju Air crash..
