Sometime ago, I read of the software that flew, I believe, the F-16. Which is fairly old technology today. I have forgotten the number of lines of code but it was easily in the 100s of thousands, and probably over a million.
Which has to perform correct under every conceivable condition.
Boeing withheld information about potential hazards associated with a new flight-control feature suspected of playing a role in last month’s fatal Lion Air jet crash, according to safety experts involved in the investigation, as well as midlevel FAA officials and airline pilots.
The automated stall-prevention system on Boeing 737 MAX 8 and MAX 9 models—intended to help cockpit crews avoid mistakenly raising a plane’s nose dangerously high—under unusual conditions can push it down unexpectedly and so strongly that flight crews can’t pull it back up. Such a scenario, Boeing told airlines in a world-wide safety bulletin roughly a week after the accident, can result in a steep dive or crash—even if pilots are manually flying the jetliner and don’t expect flight-control computers to kick in.
That warning came as a surprise to many pilots who fly the latest models for U.S carriers. Safety experts involved in and tracking the investigation said that at U.S. carriers, neither airline managers nor pilots had been told such a system had been added to the latest 737 variant—and therefore aviators typically weren’t prepared to cope with the possible risks…
…Boeing marketed the MAX 8 partly by telling customers it wouldn’t need pilots to undergo additional simulator training beyond that already required for older versions, according to industry and government officials. One high-ranking Boeing official said the company had decided against disclosing more details to cockpit crews due to concerns about inundating average pilots with too much information—and significantly more technical data—than they needed or could digest.
It’s still early in the investigation, and would be unwise to jump to conclusions. But it’ll be interesting to learn of the cause a month or year down the road.
update 11-08-2018: It apparently isn’t the software, but might be the sensors.
During the three weeks before Lion Air Flight 610 plunged into waters off Indonesia, Southwest Airlines Co. replaced two malfunctioning flight-control sensors of the same type that has been publicly implicated in the crash, according to a summary of Southwest maintenance records reviewed by The Wall Street Journal.
…Since the accident, which killed 189 people, Boeing has warned airlines about the potential for erroneous data from what are called “angle-of-attack” sensors.
If you are in a dive the only way to stop it is to flip the switch that turns off the system. Pulling back on the yoke will do nothing.
The investigation into the Lion Air crash is ongoing.