Southwest Airlines has now cancelled any flights scheduled for 737 MAX aircraft until at least October 1, following the previous decisions by American Airlines and United Airlines to cancel 737 MAX flights at least until September 3. For Southwest, the world’s largest operator of the 737 MAX, the net effect will be about 150 flights cancelled per day.
The Boeing 737 MAX has been idled worldwide following the crash of an Ethiopian Airlines flight in March, which followed an October 2018 crash for Indonesia’s Lion Air. Boeing halted assembly and delivery on the aircraft series (for which it has an order backlog of more than 4,600 aircraft), and the Federal Aviation Administration, European Air Safety Administration, and other civil aviation regulators, as well as commercial airlines, have suspended the aircraft from service.
A total of 346 passengers and crew members were killed in the two incidents, which Boeing has indicated were caused by a Maneuvering Characteristics Augmentation System (MCAS), also known as "anti-stall" software, developed to off-set a side-effect of the more fuel-efficient engines adopted for the new version of the 737: because of the engines’ larger size, the planes’ aerodynamic behavior is altered, and the MCAS is meant to counteract a stalling tendency.
Boeing officials estimate the company will complete a further 737 MAX software update by September, after the news that the Federal Aviation Administration has identified an additional programming error to be resolved through the ongoing software update.
“The FAA review and process for returning the 737 MAX to passenger service are designed to result in a thorough and comprehensive assessment,” the OEM stated. "Boeing agrees with the FAA's decision and request, and is working on the required software."
It said the new detail of the software update will reduce pilot workload "by accounting for a potential source of uncommanded stabilizer motion."
While one source noted the new detail will mean the 737 MAX will not return to service any sooner than October, Boeing asserted it not offer the update aircraft for FAA certification “until we have satisfied all requirements for certification of the MAX and its safe return to service."