Boeing says it will deploy a 737 MAX software “enhancement” across the fleet in the coming weeks incorporating feedback “received from our customers.”

According to the company, FAA will also mandate the change in an airworthiness directive (AD) “no later than April.”

The statement comes in the aftermath of two 737 MAX 8 crashes in less than five months involving Lion Air and Ethiopian Airlines aircraft. Since the March 10 accident of Ethiopian’s flight 302, a growing number of civil aviation authorities and airlines have grounded their MAX fleets.

Australia and Singapore on March 12 followed China and Indonesia as well as individual airlines like Ethiopian, Aeromexico, GOL and Cayman Airways. By contrast, US carriers American Airlines and Southwest Airlines, as well as Air Canada and European airlines, continue to operate the type.

The Oct. 29 crash of Lion Air flight 610 appears to be linked to maintenance practices, erroneous speed data input to and pilot confusion about the handling of the maneuvering characteristics augmentation system (MCAS), a new flight control law introduced on the MAX. But that investigation is ongoing and there is no indication so far that MCAS played a role in the March 10 Ethiopian accident. Both the flight data and cockpit voice recorder have been recovered from the Ethiopian aircraft wreckage, but data analysis has yet to take place.

FAA stated March 11 that “this investigation has just begun and to date we have not been provided data to draw any conclusions or take any actions.” The authority issued a Continued Airworthiness Notification to the International Community (CANIC).

According to Boeing, the enhancements include updates to “the MCAS flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading and provides a limit to the stabilizer command in order to retain elevator authority.”

Boeing said MCAS was initially introduced to improve handling characteristics and decrease pitch-up tendency “at elevated angles of attack” but not “in normal flight.” The company stressed in its statement that “the pilot will always be able to override the flight control law using electric trim or manual. In addition, it can be controlled through the use of the existing runaway stabilizer procedure (…).”

Jens Flottau, jens.flottau@aviationweek.com