Southwest Airlines and United Airlines have declined to accept new Boeing 737 MAX aircraft equipped with specific versions of flight management software. The issue concerns versions 14 and 14.1 of the Flight Management Computer (FMC) software. The Federal Aviation Administration (FAA) is currently reviewing the situation.
The software glitch occurs during precision approaches in autopilot mode. If a pilot initiates a go-around or modifies the flight plan, the system may unexpectedly switch from Vertical Navigation (VNAV) mode to other modes like vertical speed or altitude hold. Boeing states this does not pose an immediate safety threat.
Boeing is developing a permanent fix and new operating procedures to allow crews to restore VNAV functionality after such events. The company notes that pilots are trained to manage vertical paths without VNAV assistance. Meanwhile, the FAA has convened a review board to evaluate Boeing's findings and proposed solutions.
The refusal by Southwest and United is limited to the specific software configuration rather than the 737 MAX model itself. Both airlines have requested that Boeing deliver aircraft with previous, unaffected software versions. This development adds uncertainty to the certification and delivery timelines for the 737 MAX 7 and 737 MAX 10 projects.
