Boeing Max 10 certification on hold as FAA evaluates go-around software bug

The problem also affects software in the 737 Max 7 and an undisclosed number of in-service jets.
The Federal Aviation Administration (FAA) is “delaying” certification of Boeing’s 737 Max 10 to ensure a newly disclosed software issue does not compromise the safety of what is the last variant of Boeing’s narrowbody aircraft family.

Meanwhile, some pilot groups and observers are questioning why Boeing did not disclose the issue – which also affects some in-service aircraft and the newly certificated (but not yet in-service) 737 Max 7 – earlier.

“We haven’t concluded whether this is a safety-of-flight issue or not, but we will be delaying the [Max] 10 until we are satisfied that we don’t have an issue,” FAA administrator Bryan Bedford told reporters on 28 September.

Bedford does not provide more information about the certification timeline. Boeing has aimed to have the long-delayed Max 10 cleared by the FAA this year.

“We continue to follow the lead of the FAA as we work through the certification process,” Boeing says.

GE Aerospace, which developed the problematic software and is working on a fix, says, “Safety is our top priority. We are working closely with Boeing and will support the FAA’s evaluation”.

The Wall Street Journal reported on 26 September that Boeing has since 2024 been aware of a software glitch affecting the vertical navigation systems (VNAV) on some in-service 737 Max. It is unclear how many aircraft are affected, though several US airlines say they have no affected jets in their fleets.

“The aircraft are safe… Not every software is perfect,” Bedford says.

The 737 Max 7 and Max 10 variants also have software with the problem, news of which comes less than two months after the FAA certificated the Max 7. Boeing has planned to begin delivering both the Max 7 and 10 next year; it is unclear if the latest issue will upset that timeline.

The manufacturer confirms the Journal report, saying, “Last month, we informed all 737 operators about a software issue where pilots may not have access to automated flight guidance during a specific landing scenario”.

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

It affects an upgrade to a GE flight-management software – intended to “fixed a known bug” in the previous version’s VNAV, Bedford says. But the update “unexpectedly introduced a new bug”, leading in some scenarios to the “absence of vertical navigation guidance”.

The glitch arises specifically during “go-arounds” and causes affected jets’ VNAV systems to stop working.

“Following a missed approach, when a pilot alters their preprogramed flight path, the flight management computer software issue may result in the transition from a vertical navigation mode to a simpler level of automation for pitch control,” Boeing says. “All pilots are trained to safely land an airplane without” VNAV.

The company is also working with airlines to develop “a procedure” under which pilots can “re-enable VNAV”.

“Safety dictates the certification timeline. We’re following our safety review process to investigate this software glitch and won’t hesitate to take action if needed,” the FAA adds.

The agency has also convened a “Corrective Action Review Board” to review what response the software problem warrants, according to a posting on Boeing’s internal news network.

The Allied Pilots Association (APA), which represents American Airlines’ pilots, views the FAA as taking the right move in slowing the Max 10’s approval.

“We certainty commend administrator Bedford for ensuring that pilots are going to have a fully functional system, not a work-around,” says APA representative Dennis Tajer.

The VNAV’s functions include assisting pilots as they ascend during a go-around, including by showing them when to retract the jet’s flaps as it accelerates. “It’s the coach of the team, and it says, ‘Here’s where we are going,’” Tajer says of the VNAV system.

A VNAV failure during go-around could surprise pilots during a critical phase of flight – at low altitude, when the pilots are busy, he adds. “It’s not an emergency, but it’s not ideal”.

Tajer describes the VNAV issue as far less concerning than prior 737 Max concerns – specifically those involving the Maneuvering Characteristics Augmentation System, which contributed to two 737 Max crashes, and an engine-related “load reduction device” issue that can cause smoke to fill the cockpit.

But he thinks pilots should have known about the VNAV problem much earlier so they could be better prepared to address it.

Bedford says the FAA’s review of the VNAV issue primarily involves understanding the “workload component” – meaning how pilots will respond.

American and United Airlines tell FlightGlobal they have no 737 Max in their fleets with the problematic software version; neither does Southwest Airlines, according to the Journal.

The post Boeing Max 10 certification on hold as FAA evaluates go-around software bug first appeared on FlightGlobal.

Source: www.flightglobal.com — article syndicated from the publisher’s feed; all rights remain with the original publisher.