Originally Posted by
ecto1
MCAS will never help any pilot in real life. Too slow.
It doesn't matter! Certification problem, certification solution. That is probably why Boeing probably had to change from the initial 0.6 to 2.5 degree pitch down limit. As long as it meets the "test" criteria, that is the certification solution. Would the MCAS reduce the risk of a genuine stall in the real world? Irrelevant, as long as there isn't additional training, it doesn't matter.
VW did EXACTLY the same thing for emissions certification for their diesel engines, again in software. You could almost imaging the code;
if DYNO_Detection=NO---> NonComplianceMode*.
*VW actually named the compliance cheat code "acoustic condition":
A year of digging through code yields “smoking gun” on VW, Fiat diesel cheats
Once the researchers were able to study the code running on the faulty diesels, they discovered that
Volkswagen’s defeat devices were far more nuanced than anything found previously. Levchenko told Eurekalert that the “Volkswagen defeat device is arguably the most complex in automotive history.”
The researchers found that
the cars assumed they were being tested in a lab until a sensor reading ruled out a lab test. At that point, “the vehicle can switch to an operating regime favored by the manufacturer for real driving rather than the clean regime necessary to pass the emission test,”
the research paper noted (PDF).
Earlier, more basic versions of the software checked for three conditions to decide whether a lab test was being conducted. But by 2009, some firmware versions included 10 different checks for a lab test. The cars checked for things like how long and how far the car had been driven (in the US, emissions cycle tests last no more than 31 minutes and the car drives exactly 11.04 miles). Some cars also may have conducted steering wheel checks—if the steering wheel deviated more than 20° from neutral position, it was probably not being tested in the lab.
As each check ruled a lab test in or out, a different function of the Engine Control Unit—like fuel injection timing, how exhaust gas is recirculated through the vehicle, and how much urea should be injected into the exhaust—could respond.