The angle of attack sensor, at bottom center, is seen on a 737 Max aircraft at the Boeing factory in Renton, Washington, U.S., March 27, 2019. Boeing Co said on Wednesday it had reprogrammed software on its 737 MAX to prevent erroneous data from triggering an anti-stall system that is facing mounting scrutiny in the wake of two deadly nose-down crashes in the past five months. REUTERS/Lindsey Wasson

A 737 Max aircraft is pictured at the Boeing factory in Renton, Washington, U.S., March 27, 2019. The planemaker said the anti-stall system, which is believed to have repeatedly forced the nose lower in at least one of the accidents, in Indonesia last October, would only do so once per event after sensing a problem, giving pilots more control. REUTERS/Lindsey Wasson

An employee enters a 737 Max aircraft at the Boeing factory in Renton, Washington, U.S., March 27, 2019. It will also be disabled if two airflow sensors that measure key flight data offer widely different readings, Boeing said, confirming details reported by Reuters on Tuesday. REUTERS/Lindsey Wasson

Employees walk by the end of a 737 Max aircraft at the Boeing factory in Renton, Washington, U.S., March 27, 2019. "We are going to do everything that we can do to ensure that accidents like these never happen again," Mike Sinnett, Vice President for Product Strategy and Future Airplane Development told reporters on Wednesday at a Boeing facility near Seattle. REUTERS/Lindsey Wasson

Workers look over paperwork by a 737 Max aircraft on the production line at the Boeing factory in Renton, Washington, U.S., March 27, 2019. Boeing Co said on Wednesday it had reprogrammed software on its 737 MAX to prevent erroneous data from triggering an anti-stall system that is facing mounting scrutiny in the wake of two deadly nose-down crashes in the past five months. REUTERS/Lindsey Wasson

An aerial photo shows Boeing 737 MAX airplanes parked on the tarmac at the Boeing Factory in Renton, Washington, U.S. March 21, 2019. Boeing Co said on Wednesday it had reprogrammed software on its 737 MAX to prevent erroneous data from triggering an anti-stall system that is facing mounting scrutiny in the wake of two deadly nose-down crashes in the past five months. REUTERS/Lindsey Wasson/File Photo