A majority of customers who ordered 737 Max planes have now had a chance to test a fix for software that has been linked to two deadly crashes, Boeing CEO Dennis Muilenburg said.
About two-thirds of the more than 50 customers from various airlines have been able to test the software patch using a flight simulator, Muilenburg said Thursday. The software has been tested by pilots and airline leaders on 96 flights for a total of 159 flying hours.
Muilenburg did not say when Boeing 737 Max planes may begin flying again. They have been grounded worldwide since mid-March, after two crashes in about five months killed 346 people.
The Boeing chief, speaking at a George W. Bush Presidential Center leadership forum in Dallas, said the last few weeks have been the most "heart wrenching" of his career.
Authorities are still investigating the cause of last month's fatal crash involving a 737 Max flown by Ethiopian Airlines, as well as the crash last October of a Lion Air-operated Max.
The investigations are focusing on the plane's automatic safety system, for which Boeing has promised to deliver a patch and retrain pilots.
"It's our responsibility to eliminate this risk," Muilenburg said.
He added that the update will make the plane "even safer" because it will prevent "erroneous" sensor readings. A preliminary report about the Ethiopian crash that was released earlier this month did not specifically name Boeing's anti-stall system, but its findings seem to indicate that the system pushed the plane into a dive fueled by erroneous angle of attack sensor readings.
Boeing already halted deliveries of the 737 Max, which is its best-selling aircraft. The company also announced last week that it was scaling back production.
And Boeing released data Tuesday that showed orders for new 737 Max planes have come to a grinding halt: Only 10 of the planes were ordered in the first two months of 2019, and there were no Max orders last month. But thousands of outstanding orders for the plane are still on the books.
Muilenburg on Thursday said Boeing was working closely with regulatory authorities and airline customers around the globe to restore faith in the planes.
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