U.S. airlines delay Boeing 737 Max software upgrades amid safety concerns

U.S. airlines have opted to keep earlier versions of the flight-management system (FMS) software on their Boeing 737 Max aircraft, avoiding the fourth major update (U14 and U14.1) that has been linked to a series of operational anomalies. The decision predates a recent Federal Aviation Administration (FAA) review of a vertical navigation (VNAV) glitch that emerged during missed-approach procedures and was highlighted in a corrective action review board (CARB) meeting on Friday.

The FAA stated the VNAV issue does not constitute a safety risk because pilots retain full control and the cockpit indications remain clear. Nevertheless, airlines remain wary of the broader set of problems associated with the U14 software, which include loss of capabilities, crew distractions during critical flight phases, and a datalink communication fault that terminates CPDLC connections.

United Airlines and Southwest Airlines have chosen to retain the older U13 version, first installed when the Max was certified in 2017, despite its own low-risk bug that will eventually require an airworthiness directive. United previously rolled back after a 2022 incident in which a dual reset of the FMS display contributed to a runway-identification error, while Southwest has similarly declined deliveries of new Max 8 and 9 aircraft equipped with the newer software.

"Operators of 737 airplanes can continue safe operations with all approved versions of the 737 Flight Management Computer software," a Boeing spokesperson said.

"Safety is our top priority. We are working closely with Boeing and will support the FAA’s evaluation," a GE Aerospace spokesman added.

The FAA’s CARB determination is expected to clear certification of the Max 7 and Max 10 models, which rely on the latest software, without waiting for the next clean iteration (U14.2) slated for 2028. The agency also plans to issue a Special Airworthiness Information Bulletin to inform airlines of Boeing’s guidance on recognizing and mitigating the VNAV anomaly.

Airlines such as American, Alaska and Delta have confirmed that none of their Max fleets are currently operating U14 or U14.1. Southwest indicated it remains in close contact with the FAA and Boeing to address the issue, while United declined comment on the 2022 incident.

The ongoing reluctance to adopt the newer software reflects broader concerns about the interaction of software updates with hardware configurations, including memory upgrades required to protect against solar radiation and limitations on precision approach capabilities when paired with legacy hardware.