Boeing delays 737 MAX software fix delivery

Enlarge / The 737 MAX cockpit's layout is nearly identical to this 737-800's. The software behind the glass isn't. (credit: Cory W. Watts)

Delivery of Boeing's promised fix to the flight system software at the center of two 737 MAX crash investigations has been pushed back several weeks after an internal review by engineers not connected to the aircraft raised additional safety questions. The results of the "non-advocate" review have not been revealed, but the Federal Aviation Administration confirmed on April 1 that the software needed additional work.

"The FAA expects to receive Boeing's final package of its software enhancement over the coming weeks for FAA approval," an FAA spokesperson said in a statement. "Time is needed for additional work by Boeing as the result of an ongoing review of the 737 MAX Flight Control System to ensure that Boeing has identified and appropriately addressed all pertinent issues."

The Maneuvering Characteristics Augmentation System (MCAS) was developed by Boeing to mitigate changes in the handling of the 737 MAX from other 737 designs. It included a more aggressive anti-stall feature intended to counter the modified aircraft's inherent tendency to "nose up" during flight-automatically correcting the position of the aircraft's stabilizers to bring the nose back down. Evidence from the crashes of a Lion Air 737 MAX off Indonesia in October and an Ethiopian Airlines flight last month indicates that a single faulty sensor input caused the anti-stall system to activate in error, pushing both aircraft into a dive shortly after take-off. Lack of diagnostic information and a change in how pilots would normally disable the software also contributed to the Lion Air crash; the investigation of the Ethiopian Airlines crash is still in progress.

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