Flight-certification testing for Boeing's 737 MAX, which has been grounded since March 2019 because of two deadly crashes, began Monday, the Federal Aviation Administration said.
The series of flights this week will evaluate Boeing's proposed changes to the automated flight control system on the 737 MAX. The jet left from Boeing Field in Seattle at 9:55 a.m. for the first round of testing and returned to Seattle about four hours later.
The certification flights are expected to take about three days and will include a wide variety of flight maneuvers and emergency procedures to assess whether the changes meet FAA certification standards.
The tests are being conducted by test pilots and engineers from the FAA and Boeing.
The flight control system, triggered by faulty readings from sensors, pushed the planes into nosedives that led to crashes in Indonesia and Ethiopia, killing 346 people.
Even if no new problems are discovered during the test flights, it's likely to take at least a month to get pilots trained and get mothballed planes upgraded, inspected and serviced. The FAA has to sign off on Boeing's pilot-training program, and a panel of international regulators will comment on minimum pilot training too.
"We will lift the grounding order only after we are satisfied that the aircraft meets certification standards," the FAA said in a statement Monday.
Boeing said it deferred to the FAA and global regulators on the Max certification process.
Nearly 400 Max planes had been delivered to airlines before they were grounded, and Boeing has built several hundred more.