Boeing 737 Max: Planemaker completes 96 test flights with new software as Southwest grounds jet until 5 August

Boeing has completed 96 test flights on the 737 Max 8 jet upgraded with new software, as it struggles to regain the trust of airlines and global aviation regulators.

The planemaker’s CEO, Dennis Muilenberg, said that Boeing had flown 159 test hours on the upgraded jet, and that the new software had “functioned as designed”.

Speaking at the George W Bush Presidential Center Forum on Leadership in Dallas, Texas, he said that “additional test and production flights” would be undertaken in the “coming weeks”.

“As we continue working closely with our airline customers and global regulators to return the 737 Max to service, I’m focused on making the adjustments necessary to allow our teams to prioritise additional resources and focus on the recovery efforts,” he added.

Boeing has been working on a software update to the troubled Boeing 737 Max ever since the jet was grounded worldwide following the Ethiopian Airlines crash on 10 March 2019. The plane crashed shortly after take-off from Addis Ababa on a routine flight to Nairobi, marking the second deadly crash of the 737 Max aircraft following the October 2018 Lion Air crash.

The preliminary report into the Ethiopian Airlines crash revealed a struggle between the pilots and the anti-stall technology, MCAS, installed in the 737 Max.

The Aircraft Accident Investigation Bureau of Ethiopia (AIB) said that one minute after take-off from Addis Ababa, “the airspeed and altitude values from the left air data system began deviating from the corresponding right side values”. Before the 737 had been aloft for two minutes, a faulty sensor triggered a false warning of a potential stall, beginning a fatal chain of events. The captain and first officer did all they could, the report concluded, but they could not save the doomed jet.

In his remarks yesterday, Muilenberg added: “The update will make the 737 Max even safer by preventing erroneous angle of attack sensor readings from triggering the Maneuvering Characteristics Augmentation System, or MCAS, something that initial investigation reports indicate occurred in both Max accidents, as one link in a longer chain of events.”

“We’ll do everything possible to earn and re-earn that trust and confidence from our airline customers and the flying public in the weeks and months ahead.

“We take the responsibility to build and deliver airplanes that are safe to fly and can be safely flown by every single one of the professional and dedicated pilots all around the world. My team and I are working closely with our customers to answer their questions, get their feedback and ensure those who operate the Max are prepared when the grounding is lifted and the fleet returns to flight.”

Boeing has spoken to regulators and airlines in the US, Singapore, the UK and China, Muilenberg said, and more than two-thirds of pilots for airlines that fly the Max had “participated in a simulator session that included the new software update”.

It comes as Southwest Airlines, one of the biggest operators of the Max in the US alongside American Airlines, confirmed that it would ground its Max fleet until 5 August.

In a statement, Southwest said it was working to iron out its summer schedule, and would ground the troubled jet until that time to “add further stability” for customers booking vacations.

“While the timing for the return to service of the Max remains unclear, what is very clear is our commitment to operate a reliable schedule,” it said.

Affected customers would be notified of the change in schedule, Southwest said, adding that the no-frills airline would “reacommmodate” their flights in advance.

“Safety has always been our most sacred responsibility to both our employees and our customers, and we will continue to remain in full compliance with all FAA directives and any additional requirements necessary to return this aircraft to service.”

Earlier this week, American Airlines said it would ground all Max jets until early June.