Southwest and United Refuse Boeing 737 MAX Deliveries Over FMC Software Issue

September 28, 2026 at 03:20 AM2 min

This digest was compiled by AI from multiple sources — links to the originals are below.

Southwest Airlines and United Airlines have told Boeing they will not accept new 737 MAX aircraft equipped with a recently identified flight-management-computer software issue. The Federal Aviation Administration is reviewing the problem, which can cause automated vertical navigation to disengage during a specific missed-approach scenario. The affected software versions are 14 and 14.1, while Boeing says the issue poses no immediate safety threat.

Key Facts

Southwest Airlines and United Airlines will not accept new Boeing 737 MAX aircraft with flight-management-computer software versions 14 and 14.1.
The Federal Aviation Administration is reviewing the software issue, which can cause automated vertical navigation to disengage during a missed-approach scenario.
Boeing says the issue poses no immediate safety threat and has provided operators with information reinforcing existing pilot procedures.
United confirmed it does not currently have any 737s operating with the new FMC software and is not taking deliveries of aircraft with it.

Software Issue Details

The software problem affects the flight-management computer installed on certain Boeing 737 MAX aircraft. The condition can occur when an aircraft conducts a precision approach with the autopilot engaged, executes a missed approach, and then changes the pre-programmed flight plan. In this situation, the flight-guidance system can transition from vertical navigation into another mode such as level change or vertical speed. If VNAV disengages, the autopilot remains available, but pilots must manage the aircraft's vertical path differently.

Airline and Boeing Response

Boeing has emphasized that crews are trained to operate the aircraft without VNAV and is working with airlines on procedures to restore automated vertical navigation. United confirmed to Simple Flying that it does not currently have any 737s operating with the new FMC software and is not taking deliveries of new aircraft with it. Boeing is working on a permanent software update while the FAA conducts its own review.