The Boeing 737 Max 8 plane then spent nine minutes pushing its nose down, with the first officer unable to control the plane, as the captain desperately searched the handbook for a solution.
Elwell told House Transportation Committee members that Boeing expects the software update to be finished by Monday, according to a person familiar with the briefing who spoke on condition of anonymity because they are not authorized to speak on the timing publicly.
After the Lion Air crash, two USA pilots' unions said the potential risks of the system, known as the Maneuvering Characteristics Augmentation System, or MCAS, hadn't been sufficiently spelled out in their manuals or training.
Some U.S. pilots have complained they were unaware of the new system, which is mentioned in the index of the aircraft's full manual but not the text, according to a version seen by Reuters.
At the end, the sources told Reuters, the Indian-born captain, 31, was quiet, while the Indonesian officer, 41, said "Allahu Akbar" ("God is greatest") - an Arabic phrase to express excitement, shock, praise or distress.
Beijing's acquisition of the planes would help even out the trade balance between the two countries, something that was one of US President Donald Trump's key demands for a new trade deal with China.
Part of the black box of Lion Air flight JT 610.
The preliminary report showed that the plane's computer kept pushing the nose of the plane down using the trim system, which is a system that usually adjusts the aircraft to keep it on course. A stall is when the airflow over a plane's wings is too weak to generate lift and keep it flying.More news: Speaker wrecks May's Brexit plan by banning another vote on deal
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"Safety is the top priority of the Department, and all of us are saddened by the fatalities resulting from the recent accidents involving two Boeing 737-MAX 8 aircraft in Indonesia and Ethiopia", Chao said. His presence on that flight, first reported by Bloomberg, was not disclosed in the preliminary report.
Boeing was sued on Wednesday in federal court in Chicago by the estate of one of the Lion Air crash victims in which the plaintiffs referred to the Ethiopian crash to support a wrongful death claim against the company.
Boeing has said there was a documented procedure to handle the problem.
Boeing Company, the world's biggest planemaker, faces growing obstacles to returning its grounded 737 Max fleet to the skies, while details emerged of potential similarities between the two crashes.
The next day, under command of a different crew facing what investigators said was an identical malfunction, the jetliner crashed into the Java Sea killing all 189 aboard. The first officer, who was manning the control column right before the crash, seemed to become disparate, as indicated by weaker inputs than those made by the captain.
Soerjanto Tjahjono, head of Indonesian investigation agency KNKT, said last week the report could be released in July or August as authorities attempted to speed up the inquiry in the wake of the Ethiopian crash.
A Boeing spokesman declined to comment but confirmed the authenticity of the email.