- Boeing has identified a previously undisclosed software problem on certain 737 MAX aircraft that can disrupt automated vertical navigation during a specific landing scenario, prompting an FAA review and potential delivery delays.
Boeing Co. (NYSE: BA) is working on a software fix after identifying a glitch in the flight-management system of certain 737 MAX aircraft that can cause an automated navigation function to disengage during a go-around.
The issue occurs under a specific sequence involving a missed approach, autopilot use, and a subsequent change to the aircraft's programmed flight path. The Wall Street Journal first reported the problem on Sept. 26, citing Boeing documents.
Boeing told operators about the issue in August and said existing pilot procedures provide a way to safely handle the situation. The company is now developing a permanent software update. The Federal Aviation Administration is reviewing the problem and plans to convene a Corrective Action Review Board to determine whether additional action is necessary.
How the Boeing 737 MAX Software Problem Works
The glitch affects the aircraft's vertical navigation, or VNAV, function. VNAV helps the flight-management system calculate and maintain the planned vertical path during a flight. According to CBS News, the problem can arise after a precision approach is flown with the autopilot engaged, the aircraft performs a go-around, and the crew changes the pre-programmed flight path. In that situation, VNAV can disengage and transition to a less sophisticated pitch-control mode.
The autopilot itself can continue operating, Boeing said, and pilots are trained to land without VNAV. The company said it had reinforced existing procedures with operators while engineers work on a permanent correction.
The software versions identified in reporting are versions 14 and 14.1 of the 737 MAX flight-management computer operating system. It was not immediately clear how many aircraft worldwide are equipped with the affected software.
Southwest Airlines and United Airlines have told Boeing they do not want new 737 MAX aircraft delivered with the affected software and have requested an earlier version instead. Several major airlines, including Alaska Airlines, American Airlines, Southwest and United, have said their aircraft already in service do not use the software versions in question.
FAA Review Could Affect 737 MAX 7 and MAX 10
The software issue comes at an important point for Boeing's 737 MAX program. The company is preparing to deliver the recently certified 737 MAX 7 while continuing the certification process for the larger 737 MAX 10.
The FAA certified the MAX 7 in August, while the MAX 10 remains in the final stages of its long-delayed certification process. Reporting indicates that the software issue could affect the timing of deliveries or certification, although the extent of any delay depends on the FAA's review.
Boeing initially indicated that a permanent software fix could be available in 2028 but is now working to accelerate the update. The company is also developing additional guidance for pilots dealing with the affected scenario.
The FAA said it is working with Boeing and airlines to assess the issue and will take immediate action if its review identifies a safety concern. As of the latest reporting, there has been no indication that the software problem caused an accident.
For Boeing, the issue adds another software and certification challenge to a 737 MAX program that remains central to the company's commercial-aircraft business. The immediate focus is now on the FAA review, Boeing's software update, and whether airlines will continue accepting new aircraft with the affected configuration.