FAA-certification for the 737 MAX 10 aircraft is on hold again as regulators and Boeing investigators determine the scope and severity of a new software defect in the jet’s navigation system. The issue - widely reported as a “software glitch” - was uncovered by Boeing in the 737 MAX flight management computer operating system sometime in August.

A defect in the flight-control software was identified as the cause of two fatal accidents involving the 737 MAX 8, in 2018 and 2019. That program was revised during the series grounding in 2019-2020.

The current issue could cause an aircraft’s automated vertical navigation (VNAV) system to fail unexpectedly during a missed approach or reapproach, if the flight crew alters the pre-programmed flight path. In those instances, pilots are instructed to execute further procedures in order to use automated tools on subsequent approaches.

“We shared information with operators that reinforced existing pilot procedures for safely handling such cases,” according to a Boeing spokesperson, speaking to The Wall Street Journal. “Our engineers are working on a software update to permanently address the issue.”

The problem reportedly involves version 14 and 14.1 of the VNAV software, which is operable on all four variants of the 737 MAX series, though not all the 737 MAX jets currently in service are operating with the affected version of the program.

The 737 MAX 10 is the largest variant of the series. In its Q1 2026 statement, Boeing detailed that the 737 MAX 10 is in the final stage of certification flight testing for new aircraft, FAA’s Type Inspection Authorization 2, which precedes authorization of the aircraft’s conformity and airworthiness inspections.

The jet builder had been anticipating that FAA clearance before the end of this year, signaling to analysts that deliveries (and thereby, revenues) would follow in course. The smallest version of the series, the 737 MAX 7, won FAA approval in early August.

Boeing has booked over 1,400 orders from major carriers, including Alaska Airlines, American Airlines, Delta Air Lines, Ryanair, and United Airlines.

Speaking at a press conference, Federal Aviation Administration administrator Bryan Bedford stated: “We haven’t concluded whether this is a safety-of-flight issue or not, but we will be delaying the 10 ... until we’re satisfied that we don’t have an issue here.”

In a statement, FAA said “safety dictates the certification timeline,” and that it is “following our safety review process to investigate this software glitch and won’t hesitate to take action if needed.”