Originally Posted by
Semreh
Chernobyl was, in part, caused by the operators being instructed/required to run an experiment, outside the normal operating parameters, which they had not been trained on. In principle they 'should' have refused.
This
article gives a good overview of the facts immediately preceding the Chernobyl accident, this
article gives a bit more background on RMBK reactors, and
this is a rather long official report (in English) into the matter.
There is a telling quotation from that last report:
And, quoted within this report from the 3-Mile Island report:
I think,
mutatis mutandis, the same applies for pilots operating aircraft.
Chernobyl and the MAX (and THY @ EHAM) share common features of unintended behaviour by the system which the operators were not aware of. For Chernobyl, the paradoxical effect of hitting the scram button ("AZ-5") which would cause a displacement of water from the control rod channel, removing a neutron absorption mechanism, and replacing that initially with the graphite tip acting also as a moderator, leading to a massive spike in power output, many orders of magnitude above rated power output. The management of the team did not permit concerns of operators to the precipitous drop in power output from xenon-135 poisoning to terminate the test, and the consequences of the RBMK control design became known after the event. The decision making in the process was made without all the information to hand that was necessary to make a safe determination. Humans, experts and non experts don't have great batting averages with decision making under uncertainty, experts reach a position in a shorter period of time, that may be important, but the decision merit is still hit and miss. OTOH, computer systems are effective where the actual conditions are as envisioned by the programmer, any part out of round gets an poor outcome, and that is the benefit of the human in the loop; humans can ponder anomalies, and given time, can establish a counter measure. Temporal constraints have severe consequences; given time, an tentative intervention can be assessed for merit, whether the outcome is being achieved. Without time, statistics come into play. For THY at AMS, had the flightpath been at 10,000' AGL when encountering the loss of SA, then recovery would have been likely. getting to hover in a 737 at a couple of hundred feet has a high probability of ending badly. Yes, the crew missed a stack of cues as to the energy state of the aircraft that appears remarkable in the cold light of reflection, much like the splashdown of AZ-214, but that is what happened on the day, to crews that woke up expecting to have another boring day.
Recovery from a loss of SA is a challenge, and all humans suffer from SA losses at various times in their activities.