Flags flew at half-mast on Monday as South Korea mourned 179 people killed in the worst plane crash on its soil and investigators probed why the Jeju Air plane crash landed and burst into flames.

The country has begun seven days of national mourning, with the acting president flying to the crash site in southwestern Muan for a memorial as teams of US and South Korean investigators raced to establish what caused Sunday’s disaster.

The Boeing 737-800 was carrying 181 people from Thailand to South Korea when it issued a mayday call and landed on its belly before crashing into a barrier and bursting into flames.

Everyone on board Jeju Air Flight 2216 was killed, save for two flight attendants who were pulled from the wreckage.

Officials initially cited a bird strike as the likely cause of the crash, which flung passengers from the plane and left it “almost completely destroyed,” according to fire officials.

However, Seoul said on Monday it would conduct a special inspection of all 101 Boeing 737-800s in operation in the country, with US investigators, possibly including from the beleaguered plane manufacturer Boeing, joining the probe into the crash.

“We are reviewing plans to conduct a special inspection of B737-800 aircraft,” said Joo Jong-wan, head of the aviation policy bureau at South Korea’s transport ministry. South Korea has a solid air safety record.

Both black boxes of Flight 2216 — the flight data recorder and the cockpit voice recorder — have been found.

South Korean investigators said Monday that 141 of the 179 victims had been identified using DNA and fingerprint analysis, according to a statement from South Korea’s ministry of land.

Victims’ families camped out at the airport overnight in special tents set up in the airport lounge after a long, painful day waiting for news of their loved ones.

“I had a son on board that plane,” said an elderly man waiting in the airport lounge, who asked not to be named, saying that his son’s body had not yet been identified.

Memorial

At the crash site early Monday, a middle-aged man and a woman kept their gaze fixed through the fence, where remnants of the plane — seats, gates, and twisted metal parts — lay scattered across the field near the charred tail. The smell of blood was still in the air.

Soldiers carefully combed through a field of reeds next to the runway, appearing to search for body parts.

South Korea’s acting president, Choi Sang-mok, who has been in office only since Friday, said the government was making “every effort” to identify the victims and support bereaved families.

Choi, an unelected bureaucrat who became acting president after his two predecessors were impeached, said on Monday a “thorough investigation into the cause of the accident” would be conducted.

He said South Korea would conduct “an urgent safety inspection of the overall aircraft operation system” to prevent future aviation disasters.

The passengers, aged from three to 78, were all Korean apart from two Thais, authorities said.

Low-cost carrier Jeju Air “sincerely” apologized, with its top officials bowing deeply at a news conference in Seoul.

Criticism grows

Another Jeju Airlines flight using the same model aircraft experienced a malfunction linked to the landing gear and was forced to return to Seoul’s Gimpo airport shortly after takeoff, the Yonhap News Agency reported.

“We are aware of the return incident and looking into the cause,” a Jeju Air representative told AFP. “We can’t say at the moment if it was related to a landing gear malfunction pending an investigation.”

Officials pointed to a bird strike — a warning was issued by the control tower minutes before the crash — as a likely factor in Sunday’s accident.

However, a growing chorus of criticism from experts analyzing dramatic video footage of Flight 2216’s landing has focused on whether airport construction could have played a part.

Kim Kwang-il, professor of Aeronautical Science at Silla University and a former pilot, said he was “quite upset” when he reviewed video showing the plane making a skilled emergency landing but then hitting a wall.

“There shouldn’t have been a solid structure in that area at all,” he told AFP.

“Normally, at the end of a runway, there’s no such solid obstruction — it’s against international aviation safety standards,” he said. “The structure in question caused the aircraft to crash and catch fire.”