Does the CRJ-300 not have a comparator system to give a warning of ADI miss match of displays?
dixi, yes it does, but note its limitation in the aircraft, and the difference from the simulator. From the accident report.
The declutter function means that only roll and pitch angle is displayed on the attitude indicator part of the PFD units during unusual attitudes. This meant that the comparator monitor indication disappeared from the PFD 1 and PFD 2 at an early stage of the sequence.
The purpose of clearing the PFD units from unnecessary information, and thereby providing the pilots with a better display of the situation during unusual attitudes, is easy to understand. It is however more difficult to understand why indications related to instrument errors are removed.
It is possible that such an indication could have helped the pilots to identify the erroneous PFD display. Furthermore, there is a delay of more than 1 second between the caution message and the associated single chime. In case of multiple cautions and warnings, the audio alerts may be desynchronized with the visual messages, causing confusion in the flight crew’s troubleshooting.
Furthermore, as the system does not know which PFD displays the correct parameters when EFIS COMP MON triggers, no declutter function should be automatically performed in this case to avoid the removal of information useful to troubleshoot the situation.
SHK considers that the decluttering of the caution indications on the PFD displays during unusual attitudes is a weakness in the system design.
The simulator flight performed by SHK proved that the comparator caution was not removed from the PFD during unusual attitudes in the simulator.
Training experience with comparator cautions displayed during unusual attitudes might contribute to trust in a decluttered faulty attitude indicator.
System discrepancies between a simulator and the aeroplane mean that the quality of flight education and training is downgraded. This is particularly true during unusual attitudes and other malfunctions that are not normally trained in the aeroplane.