The investigation into the South Korean plane crash is ongoing, with more questions than answers about the cause

South Korean officials did promised to find out what caused it a Boeing 737-800 passenger plane operated by Jeju Air crashed in flames while attempting to land over the weekend, killing all but two of the 181 people on board. In the days after the crash, there were far more questions than answers about the nation’s worst plane crash in decades.

Authorities ordered an emergency inspection of all 737-800 planes operated by the country’s airlines after the crash — dozens of planes in total — but there was still no clear indication whether a system failure, human error or some combination of factors caused the disaster.

Experts from the US National Transportation Safety Board, the Federal Aviation Administration and Boeing were on the ground Tuesday to examine the crash site. The plane’s “black boxes”, which record information from the cockpit and aircraft systems, have been found. But officials warned that it could be months before clear answers emerge.

Here is an overview of what is known about the Jeju Air crash and some key questions emerging in the wake of the tragedy.

What happened in the crash of the South Korean plane?

Jeju Air Flight 7C 2216 took off from Bangkok, Thailand and made a scheduled landing on Sunday at Muan International Airport in southern South Korea.

After an initial failed landing attempt, the Boeing 737-800 received a bird strike warning from ground control. It then rose again before attempting to land a second time.

Two minutes later, the flight crew sent a distress call and attempted to land on another runway. The plane landed three minutes later without lowering the front landing gear.

It skidded down the runway at high speed, skidded past the runway and crashed into a concrete barrier, exploding into a ball of fire. The only survivors were two crew members rescued from the tail section.

Observers say video footage of the crash suggests the plane was suffering from engine trouble, but a malfunctioning landing gear is likely the main cause of the crash.

Officials at South Korea’s transport ministry said the plane’s flight data and cockpit audio recorders – so-called “black boxes” – were moved to a research center at Gimpo International Airport in Seoul before analysis. The ministry previously said it would take months to complete the investigation into the accident.

“I think the cockpit voice recorder, if I can read it, will be key to unlocking this mystery,” Robert Sumwalt, former chairman of the US National Transportation Safety Board, told CBS News.

Jeju Air said the crash was not due to “any maintenance issues,” according to South Korean news agency Yonhap and aviation expert Geoffrey Thomas he told BBC News that South Korean airlines are generally considered to follow “industry best practice” and that both the plane and Jeju Air had an “excellent safety record.”

The South Korean plane slid into the fence that protects the antennas

Transportation ministry officials said Monday they will investigate whether the fence the plane hit — a concrete structure that houses a set of antennas designed to safely guide planes during landing — should have been made of lighter materials that would break more easily on impact. They said they were also trying to determine if there were any communication problems between air traffic controllers and pilots.

The positioning of localization antennas near the end of the runway behind unyielding fortifications is likely to be the focus of investigators’ attention.

“Normally, at an airport with a runway, you don’t have a wall at the end,” Christian Beckert, a flight safety expert and pilot for the German airline Lufthansa, told the Reuters news agency. “You more [often] maybe have a material retention system designed to allow the plane to sink into the ground a bit” to slow it down.

Could a bird strike have caused the Jeju Air disaster?

Lee Jeong-hyun, chief of the Muan Local Fire Department, said Sunday that bird strikes and bad weather may have contributed to the accident, but stressed that the cause was still under investigation.

According to CBS News affiliate BBC News, a passenger on the flight texted relatives before the disaster and said the bird was “stuck in the wing” and could not land, but officials have not yet confirmed whether there was a bird strike.

Geoffrey Thomas, an expert quoted by the BBC and editor of Airline News, told Reuters separately that he was skeptical that the bird strike alone could have caused the fatal crash.

“Bird strikes are not uncommon. Undercarriage problems are not uncommon. Bird strikes happen much more often, but they usually don’t cause the loss of the aircraft in and of themselves,” he said.

Why was the landing gear not activated?

It remains unclear what, if any, engine or systems failures the flight crew may have been dealing with in the last few minutes of the ill-fated flight. Experts said video of the crash showed no visible movement of the plane’s flaps as it descended, which can help slow the plane, suggesting there may have been a loss of hydraulic pressure that controls mechanical devices.

The hydraulic control systems operate independently, and experts say the engine problem is unlikely to affect their operation.

The aircraft also has manual controls for the pilots to lower the landing gear in the event of an electronic or mechanical failure. It was not clear if the Jeju Air crew simply did not have time to manually lower the front wheels or if some other factor could have prevented them from doing so.

Sumwalt, former chairman of the NTSB, told CBS News, “I flew 737s for 10 years as a captain, and I can say that the landing gear can be manually deployed, so the real question is going to be what set the sequence of events here. the bird strike set up a sequence of events in which the crew rushed and did not deploy the landing gear, given that it can be deployed manually by conventional means.”

A long, difficult year for American aerospace giant Boeing

The crash capped a troubled 2024 for US aerospace giant Boeing, which has grappled with security issuesand strike of machinists and falling stock prices.

Experts say the 737-800 is a more proven model than the company’s much-maligned 737 Max jets, which were associated with fatal accidents in 2018 and 2019.

“I think it’s very important to separate this accident … from the problems that Boeing has had in the recent past,” Sumwalt said. “This plane is 15 years old, so it probably wasn’t a manufacturing problem if the plane is that old and has flown thousands of hours. It’s not a design problem. So I don’t think Boeing is going to take a direct hit because of this one.”

However, South Korean authorities said they would conduct safety inspections on all 737-800 aircraft operated by domestic airlines, including Jeju Air’s 39.

contributed to this report.