The MAX systems are integrated in the "e-cab" test flight deck, a simulator built for developing the MAX.[134][135] In June 2019, "in a special Boeing simulator that is designed for engineering reviews,"[136] FAA pilots performed a stress testing scenario – an abnormal condition identified through FMEA after the MCAS update was implemented[137] – for evaluating the effect of a fault in a microprocessor: as expected from the scenario, the horizontal stabilizer pointed the nose downward. Although the test pilot ultimately recovered control, the system was slow to respond to the proper runaway stabilizer checklist steps. Boeing initially classified this as a "major" hazard, and the FAA upgraded it to a much more severe "catastrophic" rating.