The decision, reached on October 2 by an FAA panel of internal safety experts, removes a potential obstacle to the certification and entry into service of the 737-10. It also means the recently certified 737-7 will not be subjected to a mandatory software update before entering commercial service.
The FAA’s Corrective Action Review Board determined that the software issue affecting certain Boeing 737 MAX flight computers does not constitute a safety concern because pilots remain in full control of the aircraft and receive clear indications when the problem occurs.
The agency said the issue was considered manageable because “pilots retain full control of the aircraft and the indications to the flight crew are clear and unambiguous.”
The problem can occur when pilots modify a programmed flight path while carrying out a missed approach. In certain circumstances, the aircraft’s flight guidance system can automatically switch from VNAV, or vertical navigation, to a less sophisticated form of pitch-control automation, such as level-change or vertical-speed mode.
Although the system remains controllable, the unexpected change could increase workload for pilots during a phase of flight that can already involve heightened demands.
Boeing is preparing a special bulletin explaining how flight crews can identify the malfunction and respond appropriately. The FAA also intends to issue its own bulletin reinforcing Boeing’s guidance.
Software update remains in development
Boeing and its software partner, GE Aerospace, are working on a revised version of the flight management system software to address the issue.
The affected system is currently operating on Update 14.1, commonly referred to as U14.1. Earlier versions are installed on other 737 MAX and 737 Next Generation aircraft, but U14.1 is currently the only version compatible with the newer 737-7 and 737-10 models.
The 737-10 remains in the final stages of the FAA certification process, making the regulator’s decision particularly significant for Boeing and its customers.
Boeing first became aware of the problem in 2024 after it was reported by WestJet, according to Reuters. The issue had been introduced in U14.0 but was not detected at the time.
The manufacturer subsequently investigated the matter and concluded that it required correction but did not represent a flight-safety issue. After receiving additional reports from customers during the summer, Boeing revisited the matter and brought it to the FAA for a wider assessment.
The FAA reviewed Boeing’s analysis and carried out its own independent evaluation before reaching the same conclusion.
Airlines remain cautious
While the FAA has determined that the issue does not require a mandatory update as a condition of certification, questions remain over whether airlines will be willing to accept aircraft equipped with the existing software.
The concern centres less on the level of risk than on the circumstances in which the software behaviour occurs. Some pilots and human-factors specialists have questioned whether an unexpected change in flight-guidance mode could add unnecessary workload during a missed approach.
One 737 operator conducted simulator exercises to recreate the VNAV-disengagement scenario for its pilots, according to a person familiar with the trials who spoke to Aviation Week. The pilots were not warned beforehand about the nature of the scenario and were able to manage it successfully, although the exercise “took some work,” the source said.
Some airlines have already made their position clear.
Southwest Airlines, the launch customer for the 737-7, and United Airlines, an early customer for the 737-10, have indicated that they will not accept new aircraft fitted with the affected software.
Deliveries of the 737-8 and 737-9 variants have continued, but Boeing has been reverting those aircraft to an earlier software version to address customer concerns.
The FAA’s decision therefore clears an important regulatory hurdle for Boeing, but the company still faces the challenge of completing the software update and satisfying individual airline customers as it prepares the latest members of the 737 MAX family for service.