Boeing 737 MAX fault can interrupt automated guidance after a missed approach
A software fault on certain Boeing 737 MAX jets can interrupt automated flight guidance when crews change a planned route after a missed approach. Boeing has told operators about the scenario and is working on a fix. The US Federal Aviation Administration is reviewing the issue; the number of aircraft carrying the affected software remains unclear.
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A route change can interrupt vertical guidance
A software fault on certain Boeing 737 MAX aircraft can interrupt automated flight guidance after a crew abandons an approach and changes its planned route for another landing. CNA and CBS News report the same specific scenario: a missed approach followed by a change to the programmed flight path. The affected feature is part of the flight-management computer’s vertical navigation. The fault is not a finding that every MAX landing, or every autopilot function, fails. CBS News says the fault can make vertical navigation disengage and leave a less sophisticated level of automated pitch control. Boeing told CBS that autopilot itself continues to function and that pilots are trained to land without that vertical-navigation feature. The exact sequence matters: the problem arises in a particular landing procedure after a cockpit software update, rather than on all flights equipped with the aircraft type.[1], [2]
Boeing has warned operators and is preparing a fix
Boeing said it informed all 737 operators last month that pilots may lose access to automated guidance during the specified landing. The company said it had reinforced existing pilot procedures for handling such cases safely and that engineers are working on a permanent software update. Those procedures address what crews do if the feature is unavailable; they do not amount to a completed software repair. Boeing has not supplied a count of aircraft using the affected version in the accepted desk report. The US Federal Aviation Administration said it was aware of a potential problem in the flight computers of certain 737 MAX airplanes and was working with Boeing and airlines. It said a Corrective Action Review Board would meet and that it would act immediately if it identified a safety concern. That statement records a review and a conditional response, rather than a regulator finding that the fault already made a landing unsafe.[1], [2]
Two carriers seek older software on new jets
Southwest Airlines and United Airlines asked Boeing not to deliver new 737 MAX jets with the affected software and sought an earlier version instead, according to CNA’s account of the Wall Street Journal report. CBS News says the two airlines told Boeing they would not accept new aircraft carrying that operating system. The request concerns software on future deliveries. It does not by itself say that the two carriers grounded aircraft already in service. How many aircraft carry the flawed version was not established in CNA’s report. Boeing, airlines and regulators were still assessing whether the fault creates a flight-safety concern. The 737 MAX entered this review with unusually close scrutiny after two fatal crashes in 2018 and 2019 and a later Alaska Airlines cabin-panel blowout. Those earlier incidents are background to the response to this software fault; the accepted reports do not say the new fault was involved in either event.[1], [2]
