| Aerospace engineer here. From TFA: >A component of the main electric trim system became inoperative. Our pilots ran the appropriate checklist, which included manually trimming the aircraft. They returned to MIA and landed uneventfully. The issue was not related to MCAS. That statement is from the airline, not from Boeing, so I'm more inclined to trust it. Additionally, if the airline lies and it turns up on an airworthiness audit (air maintenance organizations are subject to regular audits) then the penalties are quite severe. In any case, per the airline's statement it was an issue unrelated to MCAS. Aircraft break literally every day in a myriad of ways that are often invisible/imperceptible to people riding on that very aircraft. In this particular case it was some unspecified component of the electric trim system. You can look up the Master Minimum Equipment List for the B737[0] and see for yourself just how granular the approved maintenance program gets for aircraft like this. Everything on the MMEL is essentially an item that can be broken and the aircraft can still take off legally. Note that this is a different (and more rigorous) standard than "can be broken and aircraft can take off/operate safely". I don't know exactly what broke here but I suspect it is a part that has broken on 737s hundreds if not thousands of times in the past, with similar outcomes. I merely dabble in software but to further your analogy: This situation is when you've been dreaming about that bug for weeks and you get the call from the boss thinking it has recurred but instead it turns out it was a similar-smelling failure caused by some intern's microservice not failing gracefully when confronted with a network outage that brought down the system anyways. [0] https://fsims.faa.gov/wdocs/mmel/b-737%20r55a.htm |