Boeing 737 MAX software fault can disengage vertical navigation during landings

Quick summary

Boeing has disclosed a software fault in the flight management computers of certain 737 MAX aircraft that can cause the vertical navigation function to disengage during a go-around and second approach. The FAA has confirmed it is aware of the issue and will convene a Corrective Action Review Board to determine whether formal action is required. United Airlines and Southwest Airlines have both asked Boeing to deliver new MAX aircraft carrying an earlier, unaffected software version while a permanent fix is developed.

Boeing maintains that existing crew procedures cover the scenario and that the aircraft remain safe to operate. The regulator’s review is ongoing, and no airworthiness directive has been issued.

Boeing notified 737 MAX operators in August 2026 about a software fault that can cause the vertical navigation system to drop out at one of the most demanding moments in any flight: a go-around followed by a second landing attempt. The FAA has since confirmed it is working with Boeing and airlines and will convene a Corrective Action Review Board — the mechanism by which the regulator decides whether a manufacturer-reported problem requires a formal airworthiness response.

The fault sits in the flight management computer’s VNAV function. When a crew aborts a landing, reprograms the route, and begins a second approach, the system can disengage, leaving pilots to manage pitch manually or fall back on less capable automation during a phase of flight where workload is already high.

Boeing’s position is that standard procedures are sufficient while engineers develop a permanent software update, and that the issue does not currently constitute a safety risk. The FAA‘s decision to open a formal review — rather than accept that assessment at face value — is the tension at the center of this story. Two of the largest 737 MAX operators in the world have already voted with their delivery requests, asking Boeing to supply new aircraft with an older software build rather than the version under scrutiny.

What the FAA review actually means for the MAX program

The Corrective Action Review Board process does not automatically produce an airworthiness directive. It can conclude with no formal action, a continued airworthiness notification, or a directive requiring operators to take specific steps. As of publication, the FAA has not issued any directive tied to this fault, and the review remains open.

Boeing’s 737-10 certification timeline adds commercial pressure to the remediation schedule. According to Boeing’s July 2026 program update, flight testing for the 737-10 was complete, with remaining work focused on development-assurance reviews and system-safety assessments ahead of FAA review. Boeing’s second-quarter filing reiterated a 2026 certification target and 2027 first deliveries for both the 737-10 and 737-7. No formal revision to that schedule has been filed.

The number of aircraft currently operating with the affected software has not been disclosed publicly. Boeing has not confirmed which specific software versions are involved, and no Asia-Pacific civil aviation authority — including CAAS, CASA, JCAB, or CAAC — has issued a directive tied specifically to this fault, according to the FAA’s public statements.

Why airlines are choosing older software over newer

The requests from United and Southwest reveal something worth understanding about how operators manage regulatory uncertainty. When a software version is under active regulator review, an airline accepting delivery of that version inherits whatever compliance obligation eventually follows — retrofit, retraining, or operational restriction. Requesting an earlier build sidesteps that exposure entirely, at the cost of foregoing whatever improvements the newer version introduced.

That calculus matters for travelers because it shapes how aircraft get configured at the factory, not just how they fly afterward. Delivery configurations are negotiated between Boeing and operators, and carriers willing to accept older software are signaling that known and stable beats new and uncertain — a posture that has become more common across the MAX program since 2024.

For Asia-Pacific routes, the practical question is whether regional carriers operating the MAX will face similar choices. The 737 MAX flies across Southeast Asia, Northeast Asia, and on trans-Pacific services, and any FAA-led technical action historically becomes a reference point for other civil aviation authorities. No Asia-Pacific regulator has issued local instructions tied to this specific fault yet, but that can change if the Corrective Action Review Board produces a formal requirement.

Steps to take if your itinerary involves a 737 MAX

No airworthiness directive has been issued, and Boeing’s stated position is that the aircraft are safe to operate under current procedures — but the FAA review is live, and delivery configurations are in flux across two major US carriers.

• Check your aircraft type before departure. Use your booking confirmation or the carrier’s app to confirm the scheduled equipment. On United, the aircraft type appears in the booking record and on the flight-status page. On Southwest, check the app or flight-status tool the day before and again on the morning of travel.
• Watch for equipment-change notifications. An aircraft swap on a MAX-scheduled flight does not necessarily mean a safety restriction — it may reflect a delivery or scheduling adjustment. Read any notification carefully before assuming a cancellation or rebooking right applies.
• For Asia-Pacific itineraries, check your operating carrier. Regional MAX operators are not under a local directive yet, but that can change. Confirm the operating carrier on codeshare bookings, since the aircraft type may differ from the marketing carrier’s fleet.
• Know your rebooking rights. An equipment change alone typically does not trigger a full refund right under US rules. A schedule change of significant duration may. Check your carrier’s contract of carriage before contacting customer service.
• Monitor the FAA docket. The Corrective Action Review Board outcome is the decision that matters. If it produces an airworthiness directive, operational instructions will follow quickly. The FAA’s public docket is the authoritative source.

Watch: The FAA‘s Corrective Action Review Board finding — no fixed timeline has been published, but its conclusion will determine whether this remains a manufacturer-managed software issue or becomes a formal regulatory requirement with fleet-wide compliance obligations.

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