SAN FRANCISCO, July 8 — US investigators are trying to determine why pilots of an Asiana Airlines Inc. Boeing Co. 777 jet didn’t react to a critical loss of airspeed until seven seconds before the plane slammed into a berm short of San Francisco International Airport’s runway.

South Korea’s Transport Ministry said it’s still investigating which pilot was in control of the aircraft during the approach and landing, ministry official Choi Seung Yeon said by phone today. One of the pilots, Lee Kang Kuk, was transitioning from flying the Boeing 737 and had 43 hours’ experience on the 777, the ministry said.

The aircraft slowed so much on approach that a cockpit warning of an impending aerodynamic stall sounded four seconds before it crash-landed, US Transportation Safety Board Chairman Deborah Hersman said yesterday, describing data from flight recorders in her first briefing since the accident.

A pilot is heard on the cockpit voice recorder calling for more speed seven seconds before impact, she said. By then it was too late, as it can take 10 or more seconds from the time a pilot adds power until a jet engine revs up. The pilots tried to abort the landing 1 ½ seconds before impact, Hersman said.

“There is no discussion of any aircraft anomalies or concerns with the approach,” Hersman said. The engines responded normally to the command to increase speed, she said.

All but two of the 307 people on board -- 291 passengers and 16 crew members—survived the July 6 accident even with though a fire destroyed much of the interior. Two 16-year-old girls who were part of a 70-person group traveling from China to summer camp were killed.

Shares Slump

Asiana shares dropped as much as 9.6 per cent to 4,630 won, the lowest price since April 2010, and traded at 4,845 won (RM515.8) as of 1:44pm in Seoul.

The Asiana 777 slowed to as low as 201kph as it neared the runway, according to radar data compiled by FlightAware.com, a flight-tracking website. Hersman declined to specify the speed, other than to say it was “significantly below” below the target of 137 knots for approach.

Flight 214’s tail hit the ground and broke off, sending the jet spinning out of control, witnesses said.

Investigators are trying to determine whether one of the victims was killed by a fire truck rather than by crash trauma, San Francisco Fire Chief Joanne Hayes-White said, according to the San Francisco Chronicle.

“Based on the injuries sustained, it could have been one of our vehicles that added to the injuries, or another vehicle,” Hayes-White told the newspaper.

“That could have been something that happened in the chaos.”

San Francisco Mayor Ed Lee, at a news conference yesterday, said the crash scene was “very hectic.”

‘Confusion’

“There was just a lot of confusion,” he said, emphasizing he couldn’t confirm what happened. “And I know what was on the mind of the emergency responders that were arriving—that they had to get triage to those that were already injured on the ground, as many as they could see, and they also had to prevent a possible explosion.”

It was the first fatal crash in the US of a large jet since 2001, and Seoul-based Asiana’s first such accident since a Boeing 747 cargo plane went down at sea in July 2011.

The plane, Boeing’s largest twin-engine model, appears to have struck a seawall where pavement meets the San Francisco Bay before the start of the runway, said John Cox, a consultant who has participated in several inquiries by the National Transportation Safety Board.

The plane hit the ground more than 305 metres short of the touch-down zone.

“It’s not a little bit short,” said Cox, whose Safety Operating Systems is based in Washington. “It’s a lot short.’

Black Smoke

An amateur video that aired on CNN showed the plane’s tail hitting the ground, briefly lifting up and spinning in a cloud of dust. Black smoke began rising from the plane as soon as it came to rest.

One area investigators will examine is the lack of a radio beam pilots use to guide planes to a runway, Hersman said. The so-called glide slope indicator, which gives pilots a steady descent path, hadn’t been working since June on the Asiana flight’s runway due to construction, she said.

The US Federal Aviation Administration had posted a ‘‘notice to airmen” warning of the shutdown.

The Asiana flight had been cleared for a visual approach and didn’t need the glide slope to land, Hersman said.

The pilots had other equipment that could have guided them to the runway, she said. Colored lights on the runway tell pilots when they are too low or too high. Those lights were destroyed by the crash, she said.

Clear Skies

Weather was calm at the time of the crash, 11:36am San Francisco time. Visibility exceeded 16 kilometres, with a few clouds at 1,600 feet and winds from the southwest at 6 to 7 knots. Those conditions wouldn’t have had any effect on a 777 in normal operations.

The NTSB chairman cautioned against drawing any conclusions about the cause of the accident so soon.

“Everything is on the table right now,” Hersman said.

“It is too early to rule anything out.”

To prevent a plane’s wings from stalling, which can cause it to go out of control and plummet, cockpits are equipped with a warning system known as a stick shaker. When a plane gets within a few miles an hour of stalling, a device vibrates the control yoke and makes a loud thumping noise.

Investigators will have to determine why the pilots allowed the plane to get so slow and why they didn’t react sooner, Barr said.

“A psychiatrist almost has to answer that question,” he said.

Too Slow

The NTSB faced similar questions in probing the last fatal US airline accident, a 2009 crash involving Pinnacle Airlines Corp.’s Colgan unit in Buffalo, New York. The pilots allowed their plane to get too slow, which also prompted a stick-shaker alert, according to NTSB findings. That alert triggered an abrupt series of maneuvers that caused the plane to go out of control, the safety board found.

Among the factors the NTSB will examine in the Asiana incident are possible mechanical or computer malfunctions, pilot fatigue after a night flight across the Pacific Ocean and whether the crew communicated adequately after recognizing the issue.

The passengers on Flight 214 included 77 South Koreans, 141 Chinese and 64 from the US, according to an Asiana statement yesterday.

Summer Camp

Asiana identified the two passengers confirmed dead as Ye Meng Yuan and Wang Lin Jia. They were among 70 Chinese citizens—three groups of 60 students and 10 teachers—from the provinces of Zhejiang and Shanxi who were headed to summer camp, Wang Chuan, a spokesman for the Chinese consulate in San Francisco, said in a telephone interview.

Both girls were sitting toward the tail of the aircraft, according to Asiana Chief Executive Officer Yoon Young Doo.

San Francisco General Hospital & Trauma Center treated 53 patients, 17 of whom remain in the hospital, said Rachael Kagan, a spokeswoman, at a news conference yesterday. Six patients are in critical condition, including a child. Stanford Hospital reported having two patients in critical condition.

Dr. Margaret Knudson, a surgeon at San Francisco General, said all the patients the trauma team was able to speak with said they were sitting in the back of the plane.

Some injuries suggest some passengers were dragged, Knudson said. Four trauma teams worked on the patients, who had head, abdominal and particularly spinal injuries, including paralysis.

Maintenance

Asiana is South Korea’s second-largest carrier, after Korean Air Lines Co. The destroyed 777-200ER was among 12 of that model in Asiana’s 78-plane fleet, according to its website.

The plane was added to the fleet in March 2006, Yoon said. The plane had flown from Seoul to Osaka and back before its flight to San Francisco, and had received scheduled maintenance six months ago, Asiana said in an e-mailed statement.

The 777 is among the most-popular long-haul jetliners, because it combines the fuel efficiency of a twin-engine model with the ability to carry more than 300 people, depending on the variant and the cabin configuration. Doug Alder, a spokesman for Boeing’s commercial aircraft business, said the Chicago-based planemaker will assist NTSB investigators.

South Korea’s transport ministry is still investigating whether Lee Kang Kuk or Lee Jung Min had the controls of Flight 214 during its landing. Lee Kang Kuk, 46, has flown a total of 9,793 hours, 43 of which were on a 777, the ministry said in an e-mailed statement yesterday.

Lee Jung Min, 49, a graduate of the Korea Aerospace University who joined Asiana in 1996, has flown a total of 12,387 hours, 3,220 on a Boeing 777, the ministry said.

“It is inappropriate to prejudge that pilots were responsible for the crash, or that there were problems with the aircraft, while the investigation is ongoing,” Choi Jung Ho, an official at the ministry, told reporters today.

The accident was Asiana’s worst since 1993, when a Boeing 737 crashed in Mokpo, south of Seoul, killing 66 people, according to the National Archives of Korea. The carrier was named as the world’s fifth-best airline by Skytrax last month. – Bloomberg