It may take weeks before Boeing’s proposed software fix for a new flight-control system on the 737 MAX is even ready for air-safety regulators worldwide to consider for approval.

Boeing identified additional work in recent days that’s needed to address certification requirements, and it is continuing to refine the update.

Boeing is making significant changes to the flight-control system, which is implicated as a suspected cause of two recent fatal crashes in Indonesia last October and this month in Ethiopia that killed a total of 346 people.

In a statement Monday, Boeing said it will “take a thorough and methodical approach to the development and testing of the update to ensure we take the time to get it right.”

Boeing will submit the software update for FAA review “once completed in the coming weeks,” the company said.

The Federal Aviation Administration (FAA) said Monday that “time is needed for additional work by Boeing … to ensure that Boeing has identified and appropriately addressed all pertinent issues.”


When Boeing rolled out the software update publicly last week, Boeing vice president Mike Sinnett said it could be installed on an airplane in “about an hour.” And Boeing said the extra training required for 737 pilots would be nothing more than about a half-hour course conducted on an iPad.

Those statements stirred optimism among Boeing investors that the grounding of the jets might be quickly lifted. Since then the jetmaker’s stock price, which had been plunging, recovered somewhat, rising from $361 per share at the rollout of the fix to close at $391.54 Monday.

But worldwide approval may not be as fast as hoped.

Boeing is working on changes to a new system on the MAX known as the Maneuvering Characteristics Augmentation System, or MCAS.

MCAS was designed to kick in without pilot input in certain near-stall conditions when the plane was pitched dangerously high and to automatically push the nose down in response. However, it appears that, due to a faulty sensor, the system activated inadvertently in both recent crashes.

Boeing’s fix to the software addresses what appear to be flaws in the original design of MCAS, as reported by The Seattle Times last month, although the company last week defended the rigor of its design and characterized the changes as merely making the system “more robust.”

The main changes are that MCAS will be activated by input from two sensors instead of a single one; that it will operate only once, not multiple times, if the sensor reading remains stuck at a high value; and the power of the system will be limited so that the pilot can always pull back on the control column with enough force to counteract any automatic nose-down movement MCAS causes.


Getting the final version to the FAA is only the first step toward lifting the grounding of the MAX.

The FAA promised Monday “a rigorous safety review” and said it “will not approve the software for installation until the agency is satisfied with the submission.”

And foreign regulators in Canada and Europe have indicated that they will do their own reviews of the Boeing fix and won’t simply take the FAA’s word for it.

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We continue to seek information on the design, training and certification of the Boeing 737 MAX. If you have insights, please get in touch with aerospace reporter Dominic Gates at 206-464-2963 or To communicate on a confidential and encrypted channel, follow the options available at