By Alwyn Scott
NEW YORK (Reuters) - The world's largest pilots union rebuked the federal agency handling the investigation of Saturday's passenger jet crash in San Francisco, and said it had released too much information too quickly, which could lead to wrong conclusions and compromise safety.
Releasing data from the flight's black boxes without full investigative information for context "has fueled rampant speculation" about the cause of the crash, the Air Line Pilots Association International said in a statement on Tuesday.
The criticism came after the National Transportation Safety Board on Monday gave a detailed account of the flight's final minutes in a regular daily update on the crash.
The NTSB is the lead investigator of Asiana Airlines flight 214, a Boeing 777 that broke apart and burned after crash-landing short of the runway. Two teenage Chinese passengers were killed, and more than 180 other people were injured in the first fatal accident involving a 777 since the plane was introduced in 1995.
ALPA had criticized the NTSB on Monday for releasing too much information. But on Tuesday, it said the agency had not provided enough context, and urged the agency to "elaborate on factual material that has been excluded from public releases but must be considered in determining not only what happened, but why."
Answering ALPA's criticism, NTSB spokeswoman Kelly Nantel said the agency routinely provided factual updates during investigations.
"For the public to have confidence in the investigative process, transparency and accuracy are critical," Nantel said.
NTSB Chairman Deborah Hersman was due to brief reporters Tuesday. On Monday, she said the plane was below its target landing speed for more than half a minute before impact. That information expanded on data released Sunday that indicated the plane was below speed during the final seven seconds.
Hersman said the plane was traveling at 134 knots, or nautical miles per hour, 34 seconds before impact, well below the landing speed of 137 knots. The plane continued to slow down and when it hit the ground, the speed was 106 knots, she said.
Hersman cautioned on Monday that the NTSB and other agencies were still interviewing the four pilots from the flight, and she said it was premature to draw conclusions. She also said the flight data recorder would be cross-checked with air traffic control logs, radar and the cockpit voice recorder.
ALPA, the Washington, D.C.-based union that represents more than 50,000 pilots in the United States and Canada, said the NTSB statements gave the impression that the agency had "already determined probable cause."
Asiana Airlines, based in South Korea, has said the pilot at the controls, Lee Kang-kuk, was still training on Boeing 777 jets and his supervisor was making his first flight as a trainer. Lee had 43 hours of experience flying the long-range jet, the airline said.
Earlier Tuesday, Hersman said in a TV interview that the agency wanted to understand the pilot's experience.
Aviation experts said the low speeds during the plane's final approach suggested that the pilots probably had time to realize the plane was stalling and to react.
Passengers also have reported that the plane was rolling from side to side during the approach, which in calm winds is another indication of stalling, said Hans Weber, president of TECOP International Inc and an aerospace consultant who has been an adviser to the FAA.
As soon as a plane goes below the minimum speed for a landing, there should be a vibration in the controls meant to warn pilots of a stall, he said.
"If they had commanded full throttle at that point," Weber said, "there's a good chance they would have made it."
(Reporting by Alwyn Scott; Editing by Lisa Von Ahn, Bernard Orr)