What caused the crash?

After approaching the airport across San Francisco Bay, the plane appeared to strike the edge of the approach area of the runway. An aerial view shows that the tail came off and the aircraft left a trail of debris before coming to rest beside the runway. [REUTERS/NEWS1]

As Asiana Airlines Flight 214 crashed at San Francisco International Airport early Sunday morning Korean time, divergent opinions over the cause of the accident have been raised, but the investigation team in the U.S. said that determining the cause of the crash could take at least six months and as long as two years.

Experts said the exact cause of the crash would not be verified until the black box is examined, but they see pilot error and technical defects as the two biggest possibilities.

Foreign media outlets, including CNN and the Los Angeles Times, have raised the possibility that pilot error might have caused the accident based on descriptions by some witnesses, saying the passenger jet lowered its altitude too soon after setting the aircraft’s landing gear, possibly causing the plane’s tail to hit the seawall and break apart.

According to the National Transportation Safety Board (NTSB), which is in charge of the investigation, the jet hit a seawall dividing the airport runway from San Francisco Bay before crashing.

The JoongAng Ilbo yesterday confirmed with the Ministry of Land, Infrastructure and Transport that pilot Lee Gang-guk, who has a total of 9,793 hours of flight time, including only 43 hours for the B777 passenger jet, was in the captain’s seat during the whole flight from Incheon to San Francisco and Lee Jeong-min, a veteran pilot who has a total of 12,387 hours of flight time, including 3,220 hours with the B777, was in the first officer’s seat.

The ministry said Gang-guk used to fly the Airbus and is a trainee for the B777, but it hasn’t been verified that he actually acted as the captain when the jet was landing. No matter where a pilot sits, either can act as captain. “There is no problem with Gang-guk sitting in the captain’s seat as a trainee,” the Transport Ministry explained.

“Everything is on the table at this point,” Deborah Hersman, chairman of the NTSB, was quoted as saying. She said it can’t be determined that the accident occurred due to pilot error as of now.

The NTBS said it will look into air-traffic control records, weather, aircraft maintenance and the crew’s reactions from data recorders aboard the plane.

Some people are speculating there were technical problems with the jet, including defects in the flight’s landing gear, but Boeing’s 777 has been a relatively reliable aircraft, according to safety experts.

Some suspect the airport’s Global Positioning System (GPS) might have caused the accident, but experts said the possibility is very low. The airport’s GPS system called “glide slope,” which measures incoming flights’ descending paths for the 28L runway, which the flight 214 used for landing, was already broken. But experts currently do not see this defect as the cause determining the crash, for two reasons.

First, the glide slope is a system that helps pilot’s departing and landing but it isn’t essential.

“Without the system, only the autopilot mode becomes disabled, but pilots can land a flight in any degree by utilizing other devices that can measure the flight’s speed and altitude,” a 60-year-old retired pilot surnamed Kim who had visited the airport dozens of times told the JoongAng Ilbo.

Foreign media, including Reuters, also reported such facts by quoting retired airline pilots, who said, “If the weather is clean and the visibility distance is secured, many airports often turn off the glide slope.” The crash occurred on a day with clear skies.

Second, the Federal Aviation Administration already notified the airport’s defect through Notices to Airmen, or Notam, to airlines worldwide a long time before the accident occurred.

“We were informed that the glide slope of the runway [28L] can’t be used from June 1 to August 22,” an official at the airline confirmed for the JoongAng Ilbo on the condition of anonymity.

BY CHOI JOON-HO, KWON SANG-SOO [sakwon80@joongang.co.kr]