Authorities commenced a full-scale investigation of a helicopter collision with a high-rise apartment building in southern Seoul on Saturday morning that killed two pilots and raised concerns about the safety of flights across the city’s rising skyline.

The Ministry of Land and Transport said Sunday that its investigation team has started to analyze the data recorder, or black box, to determine the exact cause of the crash that occurred in dense fog.

“The black box analysis is expected to take about six months,” said Kim Jae-young, chief of Seoul Regional Aviation Administration under the Transport Ministry. “We are going to analyze the device (that recorded) the flight route, altitude and cockpit conversation,” he said.

The private chopper owned by LG Electronics Inc. slammed into the upper section of an IPARK apartment building in Samseong-dong, an affluent business-residential area in Seoul’s Gangnam district.

The helicopter left Gimpo International Airport at around 8:46 a.m. and headed to LG’s Jamsil heliport to pick up company executives and transport them to Jeonju on a business trip, according to company officials.

The two pilots ― Park In-kyu, 58, and Koh Jong-jin, 37 ― were killed in the accident. The collision broke windows and damaged the building’s exterior walls but left no casualties among residents, according to the Land Ministry.

It was the first time in Korea for a helicopter to crash into a building.

Investigators are likely to focus on whether or not the helicopter lost visibility due to heavy fog as well as whether the pilots were pressured to operate the chopper in poor weather.

The transport ministry said it will work closely with the Air Force to track the path the chopper flied after it took off. Police have also launched a separate probe to question family members about what happened before the helicopter departed from the airport.

The family of Park, the chief pilot, claimed that prior to leaving for the airport, he had reported to the company that the fog was too dense and suggested that the passengers board the helicopter at Gimpo instead, news reports said. He later reported that the weather conditions improved and that he would fly to Jamsil, according to the reports.

The chopper received the green light for takeoff from Gimpo authorities.

Pilots are advised to fly 300 meters away from buildings or other obstacles when going over densely populated areas. There are no specific rules for the operation of privately owned helicopters, officials said.

Some observers suggested that the chopper might have deviated from the course due to low visibility.

LG Electronics offered a public apology for the helicopter crash in a statement saying that the company will provide compensation to surviving family members of the pilots and affected apartment residents. The chopper is insured up to 22.8 billion won ($21.4 million) for victims and damage in the event of an accident.

Amid growing concerns over the safety of skyscrapers and intercity operations of air transport, the local and central government said they would conduct a thorough inspection. The government has paid less attention to business-owned helicopters compared to choppers operated by the military or other state-run agencies, observers pointed out.

The Transport Ministry said on Sunday that it would look into 33 businesses nationwide that own helicopters this month and vowed to take stern measures against any legal violations.

“We will improve the government’s safety measures for privately owned choppers as soon as the investigation into the accident is completed,” an official said.

Seoul Mayor Park Won-soon also told reporters on Saturday that the city government will soon come up with preventive measures.

There are a total of 18 skyscrapers in Seoul that are higher than 50 floors, but the city has no particular measures to ensure the safety of residents for possible aircraft accidents, officials said.

According to the ministry, four other conglomerates including POSCO and Hyundai Motors have a total of nine private choppers. Most of them are U.S.-made Sikorsky S-76C helicopters, identical to the one that crashed into the skyscraper.

Choppers are usually used when CEOs and senior executives head for factories in regional areas or to enhance travel convenience for foreign buyers visiting their business sites. They cost about 100 billion won each but companies make the investment to substantially shorten travel time, according to industry observers.

The Saturday accident has also reignited a debate over a 123-story building currently being built in Jamsil near an air base in Seongnam, Gyeonggi Province.

The Air Force has opposed the project being developed by Lotte Group, saying pilots may be distracted by the unusually high building when approaching the airport.

Despite concerns, Lotte obtained final approval from the local municipal office in 2010 and started construction immediately. The planned building is expected to become the world’s sixth highest.

By Cho Chung-un (christory@heraldcorp.com)