FAA Probes Boeing 737 Max Software Glitch That Can Cut VNAV Guidance in Go-Arounds
The Federal Aviation Administration is investigating a software glitch in some Boeing 737 Max jets that could cause an automated flight-guidance system to disengage during an aborted landing, or go-around.
The issue involves the flight management computer. In rare cases, when a pilot is flying a precision approach with autopilot engaged, executes a missed approach and changes the pre-programmed flight plan, the glitch could cause the aircraft’s vertical navigation system, known as VNAV, to disconnect and shift to a less sophisticated level of automated pitch control.
VNAV is designed to automatically maintain pre-planned altitudes at various waypoints along a flight path. If the glitch occurs, pilots would need to take additional steps during their next approach.
The scenario would typically arise near a low-altitude airport, where pilots may already be managing a high workload.
“How busy do you want your crew to be?” one airline source told CBS News about the glitch. “Are you introducing distractions at the worst possible moment?”
Boeing said it informed all 737 operators last month about a software issue in which pilots may not have access to automated flight guidance during a specific landing scenario. “We shared information with operators that reinforced existing pilot procedures for safely handling such cases,” a Boeing spokesperson told CBS News in a statement. “Our engineers are working on a software update to permanently address the issue.”
The spokesperson said autopilot will continue to function even if VNAV disengages, adding that all pilots are trained to land safely without VNAV.
In a bulletin sent to airlines late last month, Boeing told operators the glitch is not an immediate safety issue. It surfaced in versions 14 and 14.1 of the operating system for the Max’s flight management computer.
“The FAA is aware of a potential issue in a software update for the flight computers on certain Boeing 737 MAX airplanes and is working closely with Boeing and the airlines,” the FAA told CBS News in a statement. “The FAA will convene a Corrective Action Review Board (CARB) and will take immediate action if it identifies a safety concern.”
Southwest Airlines and United Airlines have told Boeing they will not accept delivery of new aircraft with that operating system, opting instead for a previous version. Alaska Airlines, American Airlines, Southwest and United told CBS News none of their in-service 737 Max fleets use the software version in question.
CBS News has learned Boeing was first told of the issue by an airline in November 2024. The company reviewed it and determined in February 2025 that it was not a safety issue.
But Boeing later received what a source described as “additional information from operators” earlier this year, prompting the manufacturer to launch a formal safety review board. The board’s findings were sent to the FAA this month and will be reviewed by CARB.
Boeing’s initial bulletin told airlines a software fix would be ready sometime in 2028 and that the company would issue updated guidance about procedures for pilots to follow in November. Boeing is working to accelerate both efforts.
The FAA review could further delay certification of the 737 Max 10, the fourth and largest variant of the Max. The Max 10 was thought to be days away from achieving FAA certification, but it remains years behind schedule. The issue could also delay deliveries of the recently certified 737 Max 7. Nearly the entire order book for that aircraft is going to Southwest.
The Max is a cash cow for Boeing and is vital to its turnaround efforts. The plane has been at the center of two high-profile crashes in 2018 and 2019 that killed 346 people and were linked to defective software. It also experienced a mid-flight door panel blowout on an Alaska Airlines flight in January 2024, an incident blamed on manufacturing mistakes.
It is notable that several U.S. airlines appear to be taking a trust-but-verify approach to Boeing on the issue, having been stung by groundings and delays caused by previous Boeing mistakes on the Max.
The Max 7 was certified with software version 14, while the Max 10 was using version 14.1 during its certification testing.
Southwest was set to start receiving Max 7 deliveries this fall. It is unclear if the airline will take delivery at this time. Alaska Airlines is supposed to be the launch customer for the Max 10.
The software glitch was first reported by The Wall Street Journal.
CBS News has also reached out to Allegiant Air for comment. The airline also operates the 737 Max.