"The failure of the plane to pressurize stemmed from maintenance the night before the flight, the report said. The maintenance crew apparently left a pressurization controller rotary knob out of place and the crew did not catch the mistake during preflight checks the next day, it said."
How vulnerable the system is ... that one vital oversite was not recognized by the trained pilots. Apparently there is no back up for such a mistake. The results are total. As was the private plane that had the same problem about a year or so ago. Totally fatal.
There is a backup. A warning sound and caution light came on. Instead of heeding the warning, apparently the pilot tried to silence it, if this report is accurate.
What is left, having the autopilot take control of the aircraft and bring it to a lower altitude?