737 Max: Two further errors discovered in the control software

Boeing has discovered two new bugs in the 737 Max's flight control software. These are not related to the MCAS system, which led to the decommissioning of the entire Max fleet in March 2019. Nevertheless, they affect critical systems: One error can lead to the failure of the autopilot on the final approach, the second to loss of control with a subsequent dive. However, Boeing said that the problems had never occurred in flight.

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The second bug concerns "hypothetical errors in the flight control computer microprocessor that could potentially result in a loss of control known as the runaway stabilizer," as reported by Reuters. Boeing is already working on corresponding software updates, but there is no date for completion. One reason for this: The age and the computing power of the flight control computers are causing more and more problems for the aircraft manufacturer.

These According to a report by The Verge, it dates back to the 1990s and were installed for the first time in 1996. At the heart of the flight control computer are two 16-bit processors that work independently of one another and thus offer a high level of reliability. From the beginning, however, Boeing limited itself to installing only two flight control computers in the 737. Hardware limitations related to new features, such as the MCAS of the 737 Max, had to be dealt with by software developers. The increasing complexity of the software in connection with the single-bit susceptibility to errors of the microprocessors has led to the discovery of several serious problems in the past few months – including the two now announced.

Nevertheless, Boeing wants to stick to its own schedule. The company anticipates that the 737 Max fleet will be able to resume regular operations from mid-2020 despite the two new problems. The US aviation authority FAA (Federal Aviation Administration) did not want to give a specific date and simply referred Reuters to the extensive, partially already ongoing test procedure. Most recently, Boeing discovered a new critical bug in January, immediately after the 737 Max stopped production. This affects the operation of monitors in the cockpit, which may not start up correctly.


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