The U.S. Federal Aviation Administration is reviewing a software issue affecting a newer flight-management and flight-guidance software standard developed for the Boeing 737 MAX, as Boeing works on a permanent solution.
The issue can occur under a specific set of circumstances during a go-around, when the aircraft is transitioning away from an approach. According to Boeing, the affected software may result in the loss of automated vertical guidance in VNAV during the manoeuvre.
Existing flight crew procedures allow pilots to manage the situation, and there has been no indication of a fleet-wide grounding or an immediate unsafe condition affecting the current MAX fleet.
The issue is nevertheless attracting attention because of its connection to the latest stages of the 737 MAX programme.
The newer software standard is associated with the recently certified 737 MAX 7 and is also being used as part of the certification programme for the larger 737 MAX 10, which Boeing is working to bring through the remaining regulatory process.
Airlines seek earlier software version
According to current reporting, Southwest Airlines and United Airlines have asked Boeing not to deliver aircraft equipped with the affected software version, instead requesting an earlier software standard while a permanent fix is developed.
Existing aircraft operated by major U.S. MAX customers including Alaska Airlines, American Airlines, Southwest and United are not reported to be using the affected version.
The FAA is reviewing the matter through its Corrective Action Review Board process, while Boeing continues work on a software update.
The timing is particularly relevant for Boeing. The MAX 7 and MAX 10 represent the final two major variants of the 737 MAX family to move through certification, and the MAX 10 in particular is important to airlines that have built future fleet plans around the aircraft’s higher seating capacity.
Boeing said earlier in September that certification of the MAX 10 was approaching its final stages.
The current issue therefore appears less significant as an operational problem for the existing MAX fleet than as another engineering and certification item Boeing and the FAA will need to resolve as the programme moves toward completing the MAX family.
Sources: Federal Aviation Administration; Boeing, open sources
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