Lion Air Flight 610 crashed off the coast of Indonesia last October, killing 189 people. Indonesian officials believe that the failure of a sensor may have caused an automated software system to prevent the aircraft from blocking. The system might have shut down the aircraft as the pilots tried to override it.
In recent tests, the simulator pilots had found that they only had seconds to shut down the system and prevent the plane from falling into a dive, the Times said, citing two unnamed individuals involved in the tests were.
The system known as MCAS "left little room for error, as originally planned and explained," says the report. "The test participants did not fully understand how powerful the system was until they flew the plane on a 737 Max simulator," the Times reported.
At least some of the tests described by the Times took place over the weekend, the newspaper reported.
On Saturday, Southwest Airlines, American Airlines and United Airlines pilots and trainers met with Boeing agents to check updated software for 737 Max aircraft in the Seattle area, where the model is being compiled by several airlines sources CNN reported Monday. The software updates are designed to reduce the triggering of the MCAS system.
The pilots performed simulated flights with The latest and updated software, said one of the sources told CNN and added that every flight had landed safely.
MCAS is a key focus of research on the Lion Air disaster and the crash of an Ethiopian Airlines Boeing 737 Max 8 aircraft in March 10, killing all 157 people on board. Both jets crashed a few minutes after takeoff, and in both cases the pilots reported problems in the flights.
In the final minutes of the Lion Air flight, pilots looked in a manual for a way to prevent the plane from falling, according to a Reuters report. In a statement on Sunday, Boeing called the weekend a "productive meeting" over the weekend and the company had more than 200 pilots and technicians and regulators on Wednesday for an informational event at the company's manufacturing facility in Renton, Washington, invited.
We're trying to provide more details about our plan to help ensure the safe return of the 737 MAX to commercial service, "Boeing said.
Updated Software Required Less Intervention by Pilots
In the simulations that run over the weekend with the current MCAS software The test pilots used existing procedures to disable the system, while test flights with the new software required less intervention from the pilots, a source told CNN.
The updated softwares developed by Boeing are used the input of two sensors nose of the aircraft, rather than one, and should not trigger the MCAS system repeatedly, which has pushed down the nose of the Lion Air aircraft so much that the pilot's attempts to regain control, were meaningless.
The Federal Aviation Administration (FAA), which is part of the effort to test the new software, declined to comment. One source familiar with the tests stated that the FAA will receive the software earlier this week.
It is not expected that the FAA will allow dozens of 737 MAX aircraft before they can fly again until they learn more about the causes of Ethiopian air crash, the source said.
Flight data and cockpit voice recordings are being analyzed in Ethiopia, where authorities have submitted segments of flight voices and data records from the aircraft's black boxes to the US embassy officials in Addis Ababa, a source of knowledge, of the CNN investigation on Monday.
David Shortell, Evan Perez, Gregory Wallace and Samira Jafari of CNN contributed to this report.